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logged in users => User Diaries => Topic started by: taylorp035 on November 06, 2010, 07:34:23 PM

Title: Treadmill Dyno
Post by: taylorp035 on November 06, 2010, 07:34:23 PM
Over the last few weeks, I have been hard at work on my new supermileage car.  We have finished a new FUEL INJECTED Briggs and Stratton 3.5hp engine.  The problem is that our old dyno that is used to test these engines is really hard to use (it's a water brake, but controlling the resistance is super touchy).  So, the new plan is to use my treadmill motor and a large array of light bulbs to make a variable load.   This way we can effectively test the engine and fine tune it to be more efficient.  It should put out  about 120v, so we should be able to run light bulbs with no problem + keep the current down.

The motor is rated for 3960 rpm @ 150v and 16 amps continuous.  The engine red line is ~4,000 rpm.

The car we are building should weigh ~80-90 lbs empty and get 1500+ mpg on a stock engine.

In the end, this means that I may have to dismantle my windmill.
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 06, 2010, 09:10:08 PM
Here are a few pictures of the car and the engine so far.  Improvements include a brushless starter motor, throwing out the lead acid batteries, full ceramic bearings on all three wheels, a drag coefficient of ~0.11, a plate clutch that allows the rear wheel to spin freely, a higher gear ratio of 12:1, wheel skirts, a speedometer good for 0.1 mph increments, and a very ambitious computer that will automatically control the plate clutch using a 5th scale airplane servo, the starter motor, the fuel pump motor, calculate the grade of the road and figure out instantaneous acceleration, mpg, and efficiency, and it will control when the engine shuts off.

(http://i52.tinypic.com/2vnfhfm.jpg)


(http://i51.tinypic.com/es4ute.jpg)


(http://i55.tinypic.com/2dtd6d3.jpg)


(http://i54.tinypic.com/2me7fpc.jpg)


(http://i55.tinypic.com/2wf690p.jpg)


(http://i54.tinypic.com/x1etkh.jpg)


(http://i51.tinypic.com/2mnfbsm.jpg)


(http://i53.tinypic.com/25sml9d.jpg)


Title: Re: Treadmill Dyno
Post by: taylorp035 on November 07, 2010, 08:30:47 PM
I can't wait until I get some wheels on it.  The rear one should be on by this Friday.  The fronts are waiting for their hubs, which have drum brakes made in England.
Title: Re: Treadmill Dyno
Post by: SparWeb on November 08, 2010, 12:09:08 AM
In the end, this means that I may have to dismantle my windmill.

Whatever it takes, man!
Ceramic bearings are bloody expensive aren't they!
You can't start with a rip-cord?  Contest rules?
If this is a college team project for you, these can be very memorable.

I remember those engine/dynamometer tests in college, too.  LOTS of fun. 

I look forward to seeing the evolution.
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 08, 2010, 04:36:56 PM
Well, you could use a pull start, but we only run the engine for ~2 seconds and then coast for a minute.  Doing that 20-30 times would be annoying.  There was ONE team that had a pull start last year (out of 25 ) and they modified a cordless drill to start their engine before the 2 days were up.

As for the ceramic bearing, yes they are very expensive.  The ones we have ran $60 a piece x 6 .....  and we are not exactly sure what the advantages are.  A big difference will come from the fact that last year's bearings had seals and the ceramics don't.  I did some very rough calculations and came they to a 2-10% increase in mileage.

Right now I am looking into exhaust and intake tuning, which could prove beneficial.  I am also looking into heating the engine up with resistors since the engine is almost always cold and engines don't like to run when they are cold.  I am looking at about 30,000 J, which should be enough to heat a small briggs block by 50-80 F.

Title: Re: Treadmill Dyno
Post by: SparWeb on November 09, 2010, 03:21:13 PM
As for the ceramic bearing, yes they are very expensive.  The ones we have ran $60 a piece x 6 .....  and we are not exactly sure what the advantages are.  A big difference will come from the fact that last year's bearings had seals and the ceramics don't.  I did some very rough calculations and came they to a 2-10% increase in mileage.

Once was looking into ceramic bearings as a replacement for steel ones.  As I remember it wasn't the seals that robbed as much energy as pre-loading forces...  The problem at the time was heat build-up not auto mileage so nothing I can remember related to that.


Right now I am looking into exhaust and intake tuning, which could prove beneficial.  I am also looking into heating the engine up with resistors since the engine is almost always cold and engines don't like to run when they are cold.  I am looking at about 30,000 J, which should be enough to heat a small briggs block by 50-80 F.

Maybe you could direct the exhaust gas back directly over the head's cooling fins?  Suicidal for an engine that runs continuously, of course, but if your bursts of engine use are short enough...  Box up the engine so that the vehicle's airflow doesn't also cool it...  Hmm Can't do the first suggestion and the second at the same time.

A good source of ideas, at least as far as the chassis is concerned, could be the international solar car race websites and blogs etc.

Google "North American solar Challenge".  Hints about how to handle the "panic" and "mad scrambles" on race-day may also help.
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 09, 2010, 03:46:39 PM
We were thinking of routing the exhaust so it would go through the fins and then out the exhaust pipe.  As for airflow, there is none.  The engine bay is pretty well protected.  There might be a little air going through the rear wheel, but I doubt very much.

As for the chassis, we don't have a frame made of metal.  It is really just the body with some carbon fiber ribs inside.  All we did was wrap pink house foam with carbon fiber and it is super strong.


Today I just spray painted a test piece of carbon fiber with white Krylon paint meant for plastic.  I will then spray it with clear coat and then wet sand it with some 1000 grit sandpaper.

I also saw for the first time our rear hub, made out of a solid chunk of aluminum.  It is extra special since it is narrower than a standard bike hub, it will accept the new ceramic bearings, the one side will have the interrupter disk for the speedometer (120 tooth), and the other side will accept one half of a hydraulically operated plate clutch.  The rear wheel should spin for ever.  I saw a video on line where a guy spun a wheel with almost no effort and it spun for 8 minutes with the ceramic bearings, compared to 1 minute for the hybrid ceramic and 30 seconds for the steel bearings. 

Title: Re: Treadmill Dyno
Post by: SparWeb on November 10, 2010, 03:30:06 PM
We were thinking of routing the exhaust so it would go through the fins and then out the exhaust pipe.  As for airflow, there is none.  The engine bay is pretty well protected.  There might be a little air going through the rear wheel, but I doubt very much.

Then watch out that exhaust can't accumulate in the cabin, if it gets out of the many joints and bends in the tubes.  You will need a firewall of course, so maybe sealing that up is not going to be difficult.

Title: Re: Treadmill Dyno
Post by: taylorp035 on November 11, 2010, 09:45:48 AM
We will have a firewall, as it is a requirement in the rules.  I'm not sure that it will be 100% air tight, but it should be pretty close.  It will not matter anyways, as the exhaust pipe must stick out side of the car.

Quote
Google "North American solar Challenge".  Hints about how to handle the "panic" and "mad scrambles" on race-day may also help.

I did this competition last year too, and it was a blast.  Our car worked for the most part last year, minus the brakes and the starter motor wanting to fall off.  Luckily, you rarely need brakes and the starter came unbolted at the very end of a run (9.6 miles), so it didn't hurt our mpg.  One of the difficult requirements to meet is the braking test, which we must show a 0.25g's worth of deceleration, which is really hard to do on super thin tires and a weird weight distribution.  Last year it took me 7 attempts to pass the test, mainly b/c only one front brake was working.  The year before, they had the brake on the rear wheel, which made it almost impossible to stop the car.  If you lock up the tire, it instantly blows, so there is no room for error.  This year, we are using dual drum brakes up front.   These brakes are only found in trikes and wheel chairs and they are only sold by a shop in England.

A major issue that we haven't solved yet is whether or not we can actually put all of the power on the ground.  The reason I say this is that we will probably have about ~60 ft*lbs of torque on the rear wheel, which is way too much.  Last year's car accelerated at about 2 m/s^2 and this year's car will be a minimum of 3 m/s^2, which is like a rocket.  Most of the car's there probably accelerated at about 0.5 m/s^2 or less.

Last night, we got our new budget passed, so we now have another $900 to spend.  The car will probably end up costing in the ball park of $7-8k, which is a lot of money.  Some teams spent $40k + last year.

Title: Re: Treadmill Dyno
Post by: ghurd on November 11, 2010, 10:41:44 AM
Goofy thought...
Add another wheel?
One with brakes that would drop down to the ground when the brakes are applied?
8" plastic kids scooter wheel with tube tires kind of wheel?

Maybe even use it as the drive wheel, retractable drive wheel, since the vast majority of the time the car will be coasting (????).
G-
Title: Re: Treadmill Dyno
Post by: SparWeb on November 11, 2010, 02:10:38 PM
A major issue that we haven't solved yet is whether or not we can actually put all of the power on the ground.  The reason I say this is that we will probably have about ~60 ft*lbs of torque on the rear wheel, which is way too much.  Last year's car accelerated at about 2 m/s^2 and this year's car will be a minimum of 3 m/s^2, which is like a rocket.  Most of the car's there probably accelerated at about 0.5 m/s^2 or less.

Ah, engines aren't they grand?  80% of the time you only need 20% of their power and the other 20% time you need at least 80% power.  And yet you have to carry around the full weight of the thing 100% of the time!

Okay you obviously don't need me distracting you with jealous vicarious commentary so get back to work!
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 11, 2010, 04:43:37 PM
Quote
Goofy thought...
Add another wheel?
One with brakes that would drop down to the ground when the brakes are applied?
8" plastic kids scooter wheel with tube tires kind of wheel?

The thought had crossed my mind and several of my teammate's minds before.  We were seriously thinking of going Fred Flintstones style with the brakes, maybe having a handle that would drag on the ground.  I think this year's design is much better when it comes to stopping, so we shouldn't have any issues.


Quote
Okay you obviously don't need me distracting you with jealous vicarious commentary so get back to work!

:)  We usually have our meetings every Friday night, from 6:30 til midnight or later.  Last time we stayed until 1:30.  I am almost done with my second paint test, where I sanded a test piece of carbon fiber (6x8") and I painted it with white and blue Krylon spray paint.  Today I put on 4 layers of clear coat and tomorrow I will wet sand it with some 1000 grit sandpaper.  I think I put too much paint on it because some of it is crackling.  The first layer was good, but I think I put too much of the second layer on (roughly 24 hr's later). 

Title: Re: Treadmill Dyno
Post by: dnix71 on November 11, 2010, 06:14:44 PM
Are pneumatic tyres a requirement? If not then why not use a solid wheel with a rubber tread. If not that, the fancy cars have had wheel speed sensors that make it impossible to "spin ze tires" on your BMW or Mercedes unless you mod chip them first. Maybe a throttle feedback control with optical sensors aimed at the ground and the back tire. If the slip exceeds a certain level, have a solenoid pull back on the throttle.
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 11, 2010, 10:02:13 PM
Quote
Maybe a throttle feedback control with optical sensors aimed at the ground and the back tire. If the slip exceeds a certain level, have a solenoid pull back on the throttle.

We should have enough sensors on this car to determine that   ;D

For this project, I have spent ~100 hours on an Excel based MPG calculator.  I can enter all of the variables known to man (engine efficiency, rolling drag coefficient, max engine rpm, air density, ....)  There are 16 variables that you can change.  On the output side, it gives you a mpg number based on your max and min velocities, and a mpg number that is the maximum possible + the speeds that you can achieve that number.  More or less, the excel spreadsheet helps me get around some really nasty integrals and thinking that I don't want to do.  It takes 45 seconds for the new answer to come up after you enter in the number.  My last change to it was adding the kinetic energy of the flywheel into the equation.

The results says that we should go from 10 to 21 mpg and start the engine 16 times.  It comes out to 4200 Joules per coast, so about 5.6 hp * seconds.  



Quote
Are pneumatic tyres a requirement?
No, but the improvements would be only better if the road was perfectly smooth.   The track that we race on is meant for dump trucks, so there are some decent cracks in the pavement.  Putting solid tires on a car with no suspension would be crazy.  You are right that it could be better, but it would make for a very heavy tire and the tires that we use are already really good.  Rolling resistance of a steel wheel would be ~0.001.  Our tires are about 0.002.  We own a tire that can go as low as 0.0008, but it's $200 a tire.

Title: Re: Treadmill Dyno
Post by: taylorp035 on November 17, 2010, 10:05:50 PM
The windmill is officially no more.  I pulled the motor like I said I would.  I then neatly stacked the wood components and all of the corresponding bolts in my basement, right next to an older windmill and my pile of VAWT blades.

I then took the motor to school, which I hope in 2-3 months we will have a running electrical dyno. 


Title: Re: Treadmill Dyno
Post by: taylorp035 on November 18, 2010, 09:42:20 AM
Last night I put together our new back wheel for the supermileage car and balanced it.  It has some new ceramic bearings in the hub which are amazing.  I spun it up with my hand and it went for 12 minutes! ;D
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 13, 2010, 10:27:18 AM
Here is the 12 min spin down test for those who don't believe or just have nothing better to do  :D

http://www.youtube.com/watch?v=edxSy2QDm5g (http://www.youtube.com/watch?v=edxSy2QDm5g)


My new record is 16 min and 55 seconds and I hope to increase that to 20 minutes.  Air drag seems to be the major contributor to it slowing down.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 08, 2011, 02:59:40 PM
UPDATES  ;D ;D ;D ;D ;D

Almost finished the body work last week.  The fuel injected engine with brushless starter motor is done (never seen anyone else do this before).  We should do some dyno testing with in a month hopefully.

Shooting for 1544 mpg (double our record) with a stock engine.  Hopefully we can break 2000 mpg and get 1st place.

We did do an accidental crash test over Christmas break.  We pushed the car at 6-8 mph into a ~1000 lb shipping pallet.  We did a lot of damage upfront, but the 4 point safety harness kept the driver safe.

(http://i55.tinypic.com/w2ev0l.jpg)

(http://i55.tinypic.com/2ighcee.jpg)

And here is a video of the starter motor.

http://www.youtube.com/watch?v=GivPYe3fvc0 (http://www.youtube.com/watch?v=GivPYe3fvc0)



Title: Re: Treadmill Dyno
Post by: SparWeb on January 08, 2011, 05:48:27 PM
Thanks for the update.
Is this for the Eco-Marathon in April, or the SAE supermileage in June?
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 29, 2011, 03:34:14 PM
Sorry for the slow reply, been really busy.

This is for SAE Supermileage in June.

We just  submitted our last request for parts to build the dyno.  We ordered v-belt pulleys, a 40" belt, (10) 300 watts light bulbs, 10 light socket bases, and a 30 A analog ammeter. 

This way we can see how efficient the engine is.  The light bulbs should allow for different loads.  I think 3000 watts should be enough... 20A * 150volts roughly.  We will test a stock engine, the electronic fuel injected engine, and we are making progress on an overhead valve engine with a higher compression ratio.  We plan on testing them all with pump gas and the iso-octane. 
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 16, 2011, 05:53:53 PM
Our budget was officially passed, so I will order the parts on Friday. 

I took a video of the test runs, but the one would get stuck processing every time when I upload it.

I hope to have a really good update in 2 weeks, 3 weeks if we are slow.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 20, 2011, 10:10:54 AM
This week we hooked up the engine to the treadmill motor with a chain.  We then hooked up 3 150w flood lights.  At about 60-70 volts, the chain would start to get jumpy.  Top speed came at 85v with almost no appreciable load on the engine.  The v-belt should be here next week.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 22, 2011, 08:16:26 PM
So if you don't need so much power from the engine, why do they give everyone one with so much power?

Or did I miss something... ? (Did a lot of reading in the last couple hours between this, the 'deep-cycle' thread, and the rules)...  :-\

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 22, 2011, 08:45:57 PM
Well,  Briggs and Stratton sponsors the event, which they have given every team a free engine every year for the last 30 years... hence we use the same old engine design that needs to be modified to get good performance.  Hence our team fuel injected one of our 10 engines that we currently own.  The best thing to do is to raise the compression ratio from the 7-9:1 up to 14:1 or even as high as 18:1, in which you can gain 50-100% in thermodynamic efficiency.  Obviously this idea is easier said than done, especially since we are doing this as a club, not a senior design project.

With only ~75 lbs on the rear tire and a static coefficient of ~0.8 and a 10:1 gear ratio, we can only put down 5 ft-lbs from the engine, which the stock one is 4.9 ft-lbs.  With the E.F.I. engine, that torque number could be higher.  Our car last year was the fastest accelerating car there, at about 2 m/s^2, which takes you from 10 - 25 mph in a jiffy (like 2-3 seconds), which is rather uncontrollable, especially when your target speeds is so critical.  This year's car is going to have a speedometer accurate to 0.1 mph ( home made) and hopefully a G -meter and a GPS unit.  We have about 5 E.E's who are making a computer for the car, in which it will control the plate clutch with the servo and the power to the fuel injection system, as well as the brushless starter motor.  This year's car should accelerate at about 3 m/s^2, which will seem like a rocket ship.  The computer will automatically kill the engine when the time is right so we waste less fuel.

As you can see by the previous posts, we are working on an electric dyno with my treadmill motor.  We plan on hooking up 3000 w of light bulbs for a consistent load on the engines, so we can test the efficiency (relative efficiency only since we don't know the efficiency of the treadmill motor).

Since everything is made of carbon fiber, the whole car with the engine and everything will only weigh ~ 105 lbs.  The EFI engine + wires = 27.6 lbs alone.  The frame rails are only about 3 layers thick, but they are unbelievably strong.  Most of the outside is 5 layers thick, but since there are no sharp edges, it is relatively floppy.  Our drag coefficient was calculated to be about 0.11 and area is 0.444 m^2, which is fairly good.  The winning team's car last year had a drag coefficient of only ~.10 but an area of only 0.28 m^2.  They got 2300 mpg, but their clutch was sticking, so they should of had a higher number.  The record in our competition is about 3000 mpg.

You could do an all wheel electric drive and be able to put down ~ 10 hp, so you could do a 18:1 compression ratio with the stock 148cc engine.  You would probably blow the head off the engine, which would be bad since it is so close to your head (like less than 1"). 

I will keep updating this thread probably every week with the updates, especially on the dyno.  Since I am the president of the club, I know just about everything, so you can ask me just about any question.  A lot of the information is on the website.  As you can see, there are 32 teams signed up already from ~ 5 different countries (truly international).
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 23, 2011, 02:02:08 AM
Sheesh... 3000 mpg?

That's virtually incomprehensible. Although apparently possible.

I guess we 'pay' a lot for the thrill, comfort, and safety features that the average passenger car provides.

On the other hand, I've always thought that running an engine full time seemed kind of unnecessary. But as you mentioned, pulse and glide does not lend to 'comfortable' very well. Every time I've used it as a tactic to just get me to the next gas station, anyone riding with me perks up as if ready to ask what is wrong... LOL But it does work. :)

One of my recurring solutions in my head has been an even higher gear (or even set of gears) that can allow the engine to run at just above idle speeds (say, 1200 RPM), so that it is running at the bottom of the torque curve for each 10 MPH or so.

In other words, 1st - 3rd, acceleration, just as they are now.  

Then:

4th, 1200RPM @ 45MPH
5th, 1200RPM @ 55MPH
6th, 1200RPM @ 65MPH

and with freeway speeds trending toward what they are... 7th, 1200RPM @ 75MPH.

Running the engine at higher RPM (even though not using the torque) still requires more fuel than a lower RPM does, and if the engine/tranny/weight/dynamics are all matched, there's no reason that an average everyday car cannot be designed this way.

Then again, I'm a control freak, and whatever I own must be a stick shift. Could be done with an automatic too obviously, but many people are more concerned with 'git' than 'got', and would rather feel the power than save the gas. Stupid IMHO, but a reality. Just look at any car commercial.

Sure, acceleration is great, but I'd rather save at the pump. Kept driving a 50cc scooter around for quite a while @ 90MPG for that reason. Granted, it wasn't the initial reason, but that's another thread (likely for another forum too). :(

And so the difference shows there too - 90MPG vs 3000MPG - there's more than just the aerodynamics in that. LOL Not sure, call me crazy, but the engine having to zip along @ 9000RPM continuously to keep 27MPH may have had something to do with it...  ???

One other question about your car I can't quite make out - the O2 sensor. Don't they have to be up to temperature to provide useful information to the computer? It would seem that 2 or 3 seconds wouldn't be enough to get it hot enough to give good data... ?

Steve
  
Title: Re: Treadmill Dyno
Post by: Bruce S on February 23, 2011, 12:47:13 PM
taylorp035;
Could I ask a small but important favor?
For the building of the frame and body using the carbon fibre , could you post some of the pics over in the transportation area too ;D
Please
I have a great amount of interest in this, partly because I used to teach small engine repair for the local public school system way back in '79 ( was a fill in for the regular teach while he recovered from back surgery) and i never lost the thrill for building with these engines.
I am also curious about the compression ratio. I know "we" used to shave then polish the head all the while checking to make sure the spark plus didn't put a whole in the piston.
14:1 sure, but 18:1 WOW! what is the fuel type? if only using petrol how do you keep it from auto-igniting? or is it because it's run so short of a time the engine stays cool enough to not be too much of a problem.

Many Thanks for some great info in these posts.
Bruce S
 

Title: Re: Treadmill Dyno
Post by: Bruce S on February 23, 2011, 12:57:39 PM
Sure, acceleration is great, but I'd rather save at the pump. Kept driving a 50cc scooter around for quite a while @ 90MPG for that reason. Granted, it wasn't the initial reason, but that's another thread (likely for another forum too). :(

And so the difference shows there too - 90MPG vs 3000MPG - there's more than just the aerodynamics in that. LOL Not sure, call me crazy, but the engine having to zip along @ 9000RPM continuously to keep 27MPH may have had something to do with it...  ???

Steve
  
Steve;
One of the cool little things "we" would do with the 49cc scooters, once the warranty had expired  8) , was to get into the CV area , there's fly-weights in there and using different weights you could "tune" the bottom end and top end.
The weights I believe started out at 150grams ( don't quote me on that).
For heavier people who had problems with getting going, we would adjust for more torque on take off for people who wanted a better "zip" to top end we would adjust the weights accordingly as well.
One quick way to have better over all performance was to go get a drill and small bit 5/16" remove the chrome cover off the back of the muffler and drill 3 equally spaced holes. This would allow the engine to exhale a little better, so zip was noticed without major  surgery.

best we could get was 105 mpg consistently, 3000 would be astounding!!
Cheers;
Bruce S


 
Title: Re: Treadmill Dyno
Post by: ghurd on February 23, 2011, 01:40:49 PM
"3000 would be astounding!! "
I agree.  A lot.
Hope I did it right...

3000MPG is (in US measurements) -
4 miles per teaspoon.
12 miles per tablespoon.
308 miles per (ghurd's) coffee mug.
and
NY, NY to LA, CA... with 61 teaspoons left in a 1 gallon tank.

Wow!
G-
Title: Re: Treadmill Dyno
Post by: Bruce S on February 23, 2011, 02:32:27 PM
I'm still working out the dynamics of the 18:1 compression ratio  ;D
My MB 300TD is sitting nicely at 20:1 , I know it is supposed to be closer to 21:1, but with 177K on it and taxes coming due  :-\

Even ethanol auto-ignites around 15:1? not sure of that , never had the testicular fortitude to find out  :o .

Having too much fun working with these numbers  8)
Bruce S
 
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 23, 2011, 04:14:55 PM
Yay, you guys bit the bait  ;D

Quote
And so the difference shows there too - 90MPG vs 3000MPG - there's more than just the aerodynamics in that. LOL Not sure, call me crazy, but the engine having to zip along @ 9000RPM continuously to keep 27MPH may have had something to do with it...  Huh

One other question about your car I can't quite make out - the O2 sensor. Don't they have to be up to temperature to provide useful information to the computer? It would seem that 2 or 3 seconds wouldn't be enough to get it hot enough to give good data... ?

The best mpg would be at a constant speed, since air drag is exponential ( squared ) in terms of mpg.  Also, for the difference in mpg, look at these numbers:  10-15 x less weight, a CD * A of only 0.04 instead of 20-30 times higher (wikipedia has lots of info on this).  Transmission is about 95-98% efficient, also there is no alternator.  The Rolling resistance coefficient is also much lower, which 0.0008-0.0024 instead of 0.006-0.008 for a car.


As for the O2 sensor, we program the computer to have a start up mode pretty much, in which the software can learn the "fuel map".  Apparently the O2 sensor works pretty quickly, but I didn't build the engine.


Quote
Sheesh... 3000 mpg?

The record is about 3,000, but if last year's 1st place car actually ran well, they could of had 4000+ mpg.  The record for any type of ICE engine is significantly higher but I don't know the number... the record for a hydrogen fuel cell with the equivalent amount of energy is 12,000 mpg, but their rules were a little looser than ours.


Quote
For the building of the frame and body using the carbon fibre , could you post some of the pics over in the transportation area too Grin

Umm... I wish my school's website would be accessible to you guys.  It has about 130 pictures and 20 videos...   Maybe if I have more time this week end.

As for the carbon fiber, the stuff is best stuff in the world.  It's easy to make and requires no skills.  Basically you mix the 2 part epoxy to the directions and add glue to your carbon fiber fabric.  The hard part is not to get anything stuck the to carbon fiber, so for this problem you use lots of ceran (plastic) wrap.  Anything made of the same plastic will not stick to the glue (like bubble wrap).  Lexan is good for making shiny smooth surfaces.
For the cost, 1 yd of 60" wide is $20-50, so it's worth it for small projects.  I'm not sure how much we have in the car right now, but it is probably 30yd^2 at least.

If you want to make a beam, basically wrap C.F. around some foam (we use the pink house insulation).


As for the compression ratio, you are right.  Regular gas would ignite.  Hence we are provided with iso-octane, which will not pre-ignite.  Hence an 18:1 ratio is possible.  We don't actually have an engine that is 18:1, but there are some older engines that run at 14:1.  The downside is that 100- octane gas is $200 per gallon.  You could run 93 pump gas in the engines with the lower compression ratios with no loss in power.  At $200/ gallon, the cost benefit doesn't exist anymore.  The competition usualy gives away the extra fuel, which usually amounts to a gallon per year.  We probably have ~8 gallons in storage.  I hope the stuff doesn't go bad   :P



Quote
"3000 would be astounding!! "
I agree.  A lot.
Hope I did it right...

3000MPG is (in US measurements) -
4 miles per teaspoon.
12 miles per tablespoon.
308 miles per (ghurd's) coffee mug.
and
NY, NY to LA, CA... with 61 teaspoons left in a 1 gallon tank.

We used about 30 grams of fuel last year I believe.  If you go to the sae website, the 2007 year has data on the fuel used for each car to 5 significant figures.  Last year we used about a film canister for 9.6 miles.  I think my calculations were about 33 grams at 777 mpg, but that may be off by 10-20%.


Quote
best we could get was 105 mpg consistently, 3000 would be astounding!!
Cheers;

You have a drag coefficient of 0.7+, a bad engine, and bad tires.


Quote
I'm still working out the dynamics of the 18:1 compression ratio  Grin
My MB 300TD is sitting nicely at 20:1 , I know it is supposed to be closer to 21:1, but with 177K on it and taxes coming due  Undecided

Even ethanol auto-ignites around 15:1? not sure of that , never had the testicular fortitude to find out  Shocked .

Having too much fun working with these numbers  Cool

I'm not an expert in this field, but there are a lot of issue with the higher compression.  A smaller bore diameter would definitely be required ( we have a block with a 50cc cylinder ).




I can't wait til we get the transmission in the car and we build the cooled seat.  The transmission will be a single friction plate clutch.  We may not have enough force on the plates, so we may have to add teeth to the plates.  This would require some timing challenges between the clutch engagement, the tire rpm, the engine rpm, and the tire rpm.


If anyone was wondering about the bearings, we have 6 full ceramic bearings in the three tires.  Using full ceramic bearings instead of steel bearings with seals helps a lot.  We spun our tires by hand, and they rotated for 16 minutes!  The steel bearings only rotate for about 30 seconds.  The bearing resistance is only about 1% of the rolling resistance.  Hence our car should roll for about 2 minutes while coasting from 20 mph to 10 mph on flat ground.  In reality, most of the course is at about a -0.1% grade, so I have coasted for 0.8 miles while going from 34 mph to 4 mph   ;D  The back curve on the track is about a 1% grade, which is very noticeable in these cars.  We would have to fire the engine twice to get up the hill.





Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 23, 2011, 05:24:34 PM
Damn... haha Talk about thinking WAY outside the box...

All of what you're saying makes perfect sense to me, but there's little to no (closer to no) chance in hell I would have ever thought of all of this if I were designing something like what you all are doing with these things.

While it's true, every little tiny detail adds up, I'm surprised nobody mentioned something like the driver not eating for 3 days before the run, and taking diuretics to reduce the weight by that much more!

Ok, well, now I have... LOL so hmmm... has it been done?

I'd be willing to bet that regardless, the shortest, twiggiest guy on the team ultimately ends up becoming the driver.

While I'm on the subject, how much does driver skill play into this? Like percentage wise? Or is that a well known 'constant'?

Steve
Title: Re: Treadmill Dyno
Post by: ghurd on February 23, 2011, 06:39:04 PM
I keep coming back to something from the other post-
"for our cooled seat, which may require a good 200 watts while running".
Put an ice cube in his mouth when he starts, and let him sweat?

Wondering, since it is almost an antique engine, are the antique efficiency boosters done?
(port & polish the head, intake, and exhaust, plus make sure the gaskets are not goofing up the works)
G-
Title: Re: Treadmill Dyno
Post by: Bruce S on February 23, 2011, 06:50:49 PM


Quote
For the building of the frame and body using the carbon fibre , could you post some of the pics over in the transportation area too Grin

Umm... I wish my school's website would be accessible to you guys.  It has about 130 pictures and 20 videos...   Maybe if I have more time this week end.

As for the carbon fiber, the stuff is best stuff in the world.  It's easy to make and requires no skills.  Basically you mix the 2 part epoxy to the directions and add glue to your carbon fiber fabric.  The hard part is not to get anything stuck the to carbon fiber, so for this problem you use lots of ceran (plastic) wrap.  Anything made of the same plastic will not stick to the glue (like bubble wrap).  Lexan is good for making shiny smooth surfaces.
For the cost, 1 yd of 60" wide is $20-50, so it's worth it for small projects.  I'm not sure how much we have in the car right now, but it is probably 30yd^2 at least.

If you want to make a beam, basically wrap C.F. around some foam (we use the pink house insulation).


As for the compression ratio, you are right.  Regular gas would ignite.  Hence we are provided with iso-octane, which will not pre-ignite.  Hence an 18:1 ratio is possible.  We don't actually have an engine that is 18:1, but there are some older engines that run at 14:1.  The downside is that 100- octane gas is $200 per gallon.  You could run 93 pump gas in the engines with the lower compression ratios with no loss in power.  At $200/ gallon, the cost benefit doesn't exist anymore.  The competition usualy gives away the extra fuel, which usually amounts to a gallon per year.  We probably have ~8 gallons in storage.  I hope the stuff doesn't go bad   :P


You have a drag coefficient of 0.7+, a bad engine, and bad tires.


Quote
I'm still working out the dynamics of the 18:1 compression ratio  Grin
My MB 300TD is sitting nicely at 20:1 , I know it is supposed to be closer to 21:1, but with 177K on it and taxes coming due  Undecided

Even ethanol auto-ignites around 15:1? not sure of that , never had the testicular fortitude to find out  Shocked .

Having too much fun working with these numbers  Cool

I'm not an expert in this field, but there are a lot of issue with the higher compression.  A smaller bore diameter would definitely be required ( we have a block with a 50cc cylinder ).

I can't wait til we get the transmission in the car and we build the cooled seat.  The transmission will be a single friction plate clutch.  We may not have enough force on the plates, so we may have to add teeth to the plates.  This would require some timing challenges between the clutch engagement, the tire rpm, the engine rpm, and the tire rpm.


If anyone was wondering about the bearings, we have 6 full ceramic bearings in the three tires.  Using full ceramic bearings instead of steel bearings with seals helps a lot.  We spun our tires by hand, and they rotated for 16 minutes!  The steel bearings only rotate for about 30 seconds.  The bearing resistance is only about 1% of the rolling resistance.  Hence our car should roll for about 2 minutes while coasting from 20 mph to 10 mph on flat ground.  In reality, most of the course is at about a -0.1% grade, so I have coasted for 0.8 miles while going from 34 mph to 4 mph   ;D  The back curve on the track is about a 1% grade, which is very noticeable in these cars.  We would have to fire the engine twice to get up the hill.

Thanks for the info on building this with CF!!
Iso-Octane will absorb moisture if it is not kept in a closed container, yep it'll go bad. BUT good thing is it'll still be good for standard road type engines.

For a better engine, a bore that increases flame spread would be your best bet. Shorter stroke to reduce possibility of the pressure increase , which is not linear with regards to compression ratios. a more squat based cylinder with a piston head that could cause vortex mixing and shorter stroke would be the way I would go, but my thinking is that you cannot fidget with the internals of the engine to that degree.

See what you did , now I gotta go get my old M.E. books out and work that design out.
Bummer that I'm poor .
Again thanks for all the updates and answering these Qs  really is appreciated !
Bruce S

 

 
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 23, 2011, 10:36:51 PM
Quote from: Ghurd
I keep coming back to something from the other post

I do too, but I think there may be differences as to why. Mine is, cooling the seat is the one part of the car that I would have never bothered with. Unless we're talking extended runs here, which does not appear to be the case. Correct me if I'm wrong.

And even with extended runs (take NASCAR for example), they run for a few hours without anything like that (to my knowledge).

So why do it for this? Seems like the added weight of the water and associated electronics/components needed to cool the seat will offset your weight factor a fair amount...

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 23, 2011, 10:51:09 PM
Quote
I'd be willing to bet that regardless, the shortest, twiggiest guy on the team ultimately ends up becoming the driver.

While I'm on the subject, how much does driver skill play into this? Like percentage wise? Or is that a well known 'constant'?

The minimum driver weight is 130 lbs.

As for percentage for mpg, I would say up to 20% for a sane person.  Previous people with our same car have gotten 400 mpg, but they were driving at 30 mph average, or even as high as 50 mph.
This year's car will be easier to control the speed, so I would say closer to 5%.


Quote
Wondering, since it is almost an antique engine, are the antique efficiency boosters done?
(port & polish the head, intake, and exhaust, plus make sure the gaskets are not goofing up the works)

Yes sir, all ported and polished.  Last year's engine was 100% stock, so we may have a big gain right there.


Quote
I do too, but I think there may be differences as to why. Mine is, cooling the seat is the one part of the car that I would have never bothered with. Unless we're talking extended runs here, which does not appear to be the case. Correct me if I'm wrong.

And even with extended runs (take NASCAR for example), they run for a few hours without anything like that (to my knowledge).

So why do it for this? Seems like the added weight of the water and associated electronics/components needed to cool the seat will offset your weight factor a fair amount...

You would be wrong about the nascar cooled thing.  They have cold packs and various other things to keep the driver cool in the 140 degree F car.  Our car is kinda of the same.  I like to call it the easy bake over since it gets so hot.    We did have an electric ducted fan in the nose of the car (from a model rc jet), which could produce ~50 mph winds inside of the car.  Unfortunately, we had a significant crash while testing over Christmas, and it was destroyed.  The run takes a minimum of 38 minutes to complete + fueling time, so you could be in the closed car for 50 minutes on tarmac on a 90 degree day.

As for the weight of the cooled seat, we are making the whole thing removable.  The system may weigh 5-10 lbs, so we may remove it after we get some good runs in when we want to squeeze those last few mpg's out of the car.  Last year's numbers were, in order: 650, 678, 69x, 776.59, 630, DNF.  The 630 mpg was because I tried doing only 3 burns to get around the track, which meant my speeds went from 30-4 mph.  The 776.59 came after we pumped the tires to 55 psi, emptied every last item out of the car, and removed the air filter.  Also, the driver was the lightest of our 3 drivers, at exactly 130lbs with the helmet on...  and she drove the car at a slower speed (24-10 mph).  According to my excel mpg calculator, we should of been able to get ~ 850 mpg if it was driven slower.



Title: Re: Treadmill Dyno
Post by: SparWeb on February 24, 2011, 02:03:46 AM
Have you heard of, or already considered a NACA duct?  It could introduce a flow of air into the cabin with the least disturbance to the external flow of air around the car.  Unfortunately that would make the cooling speed-dependent, but if the bulk of the heat is coming from the engine and motors, then the sources of heat are speed-dependent too.

A reflective coating on the windshield would cut down on solar heating.

...and you're going to paint the car white, right?  :P



You would be wrong about the nascar cooled thing.  They have cold packs and various other things to keep the driver cool in the 140 degree F car.  Our car is kinda of the same.  I like to call it the easy bake over since it gets so hot.    We did have an electric ducted fan in the nose of the car (from a model rc jet), which could produce ~50 mph winds inside of the car.  Unfortunately, we had a significant crash while testing over Christmas, and it was destroyed.  The run takes a minimum of 38 minutes to complete + fueling time, so you could be in the closed car for 50 minutes on tarmac on a 90 degree day.

As for the weight of the cooled seat, we are making the whole thing removable.  The system may weigh 5-10 lbs, so we may remove it after we get some good runs in when we want to squeeze those last few mpg's out of the car.  Last year's numbers were, in order: 650, 678, 69x, 776.59, 630, DNF.  The 630 mpg was because I tried doing only 3 burns to get around the track, which meant my speeds went from 30-4 mph.  The 776.59 came after we pumped the tires to 55 psi, emptied every last item out of the car, and removed the air filter.  Also, the driver was the lightest of our 3 drivers, at exactly 130lbs with the helmet on...  and she drove the car at a slower speed (24-10 mph).  According to my excel mpg calculator, we should of been able to get ~ 850 mpg if it was driven slower.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 24, 2011, 02:25:07 PM
Quote
Have you heard of, or already considered a NACA duct?  It could introduce a flow of air into the cabin with the least disturbance to the external flow of air around the car.  Unfortunately that would make the cooling speed-dependent, but if the bulk of the heat is coming from the engine and motors, then the sources of heat are speed-dependent too.

A reflective coating on the windshield would cut down on solar heating.

...and you're going to paint the car white, right?  Tongue


Yes, we plan on having a base coat of white.  If the carbon fiber gets too hot, the glue will get soft and bad things start to happen.
I have not heard of a NACA duct, but maybe my team member who is into F1 may know about it.
As for the source of the heat, most of it will be from the sun and the driver.  The engine barely gets warm.  Most likely, we will run the car a bunch before we go drive around the track so everything is more efficient.

 
Title: Re: Treadmill Dyno
Post by: SparWeb on February 24, 2011, 03:18:57 PM
Funny coincidence, there is a NACA duct on that e-trike photo that just got posted on your other thread!

Google "NACA Duct" and you'll get lots of pictures, plus a bunch of mis-uses and confusing info.  Best to go to the source.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090012113_2009011314.pdf

(12 MB download)

Yeah yeah yeah, your grandparents were old when it was published, I know.  But let that give you some idea of how good an idea it is, since it's still around.


As for carbon fibre and heat - common problem.  You can actually get temperature-sensitive stickers, that change colour at a specific temperature.  These are used in composite aircraft and the pilot is supposed to check them before flight.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 24, 2011, 04:37:50 PM
If we bring a lot of air in, the air must go out of the wheel skirts, while may cause more of a disturbance than it is worth.  But thanks for it anyways, it is definitely a possibility.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 24, 2011, 09:24:42 PM
Today we got 23 items that we had ordered.  This included out v-belt and our two pulleys, so we can now hook up the engine to the treadmill motor tomorrow night and it should run a lot smoother than chain.  We also got the 10 light bulb bases, but the light bulbs or ammeter have not arrived yet.

We also ordered some low rolling resistance tires.  Unfortunately, Michelin is not making any of the good tires this year, so we bought some Schwalbe tires ($300 worth, for 6 tires, 2 different brands).


I should give an update sometime Satuday I would think of the progress.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 24, 2011, 10:10:46 PM
Did some experimentation with this last tank of gas in my car... Still got some more to do to make it more 'valid' data (that whole multi-sampling thing). It's a 2011 Toyota Camry with ~6K miles on it, 'rated' 33MPG highway (which is where I do a fair chunk of my driving).

While I started out with a 1/4 tank of gas, I only really applied it all after the idiot light came on, I'm a mile watcher, comparing needle to trip odo regularly and religiously. So this has some merit, even though its really only a single 'event'. After the idiot light appears (~1/8 tank), its good for about 40 miles with my normal driving style before things get scary (bad side of E).

I had to run all over BFE today, and normally, I would have had to gas up LONG before I did, but I thought about a few things we were discussing, and applied what I could to see what would come of it.

1 - Keeping raw speed down. Kept it below 65, even in the 70 zones. Was running more like 60. If you were one of the people that flew past me glaring, kiss my #@%, at least I was in the right lane!  ;D

2 - Keeping engine RPM down. Went to as high of a gear as quickly as possible.

    A - From a dead stop, only very short acceleration hits on 1st and 2nd gear (fair throttle, but limiting to ~3K RPM).

    B - 3rd was a little more lax on the throttle, and shifted out at ~2500 RPM.

    C - 4th was never allowed more than the throttle being cracked open, and limited to 2000 RPM.

    D - 5th and 6th (except where I was forced to bring the speed up due to traffic conditions) were also kept cracked at most, and target RPM was always less than 2000. I started out trying my 'out-the-hat' 1200 RPM, but this is down just a touch too far on the torque curve to be practical. Car was also groaning. So I upped it little by little until I found the lowest RPM that didn't squawk. Turned out to be ~1400 RPM. Tried my best to stay in the 1400-1600 range for a majority of the 'test'.

3 - Drafting. While I was only presented the opportunity twice, but they were both for decent runs, and I slid in as good as I could get without freaking the truckers out. I guess it's dangerous, but it's also damn appealing! The closer you get, the better the savings. I hung out at about the 50 ft mark @ 60 MPH-ish which works out to something like 20% savings IIRC (according to mythbusters test...). I probably got in all of about 20 miles collectively under draft conditions.

4 - Pulse and Glide. While the pulse part was minimal, I did a lot of coasting anywhere there was a hill, to keep engine speed down that much further. Did this countless times during my adventure today.


My round trip was on the order of ~100 miles, and the idiot light came on about 25 miles in. By fairly repeatable math, I would have had to refuel just after leaving my furthest destination, ~65 mile mark. That's when the needle looks as scary as I'll ever let it.

The results of applying the above however are rather astounding, and even more so because they only were applied to the last 1/8 tank.

Since I track my mileage, I could easily look back at similar tank fills, and see the corresponding distance. Typical 'damn, thats scary' happens at about 450 miles. This works out to 17.6 gallons of fuel, rendering 25.5 MPG. Yeah, I have a tendency to 'get on it'... heh. I'm normally one of those 'get it up quick, and hold it 10 over' type guys.

This tank, I did finally have to stop, as it hit the bad side of E about 10 miles from home, and all said and done, 514.2 miles on this tank! Pump said 17.7 gallons. 29 MPG! ;)

Even after the fill, I continued the 'economic' style, and I have a very long trip ahead of me tomorrow, which I will continue to use it then as well. Don't think it will run me out of gas, but I'll have a good idea just by gazing at the needle to figure out about where it stands.

Till then,

Steve
Title: Re: Treadmill Dyno
Post by: RP on February 24, 2011, 10:32:17 PM
I used to have a 93 Cadillac Deville with the mpg display and tried a lot of experimenting like this.  It was a 4 speed automatic but I found that by letting up on the pedal at the right speeds I could get it to upshift early to keep the rpms down.

Also I changed my route to favor stops at the top of a hill rather than at the bottom (if I had a choice) so that rather than converting all my kinetic energy to heat in the brakes, some of it was essentially stored as potential energy I could get back when starting off again.

As to drafting, I found there was a spot about 1.5 seconds behind a semi where my mpg jumped up by about 3-4.  This is a little closer than the 2 seconds recommended for safe driving but it felt safe to me.

By paying attention to all this stuff and trying to avoid using the brake pedal as much as possible I could raise my average mpg from about ~16 to about 23.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 24, 2011, 10:37:15 PM
I have tried the same thing with my 99' olds 88.  I usually average 22-23 mpg, as low as 21 if you have a foot made of lead.  If put the cruise on at 55 mpg on the high way (half of my trips), and never break 40 on the rest of my journey, I can do 24 mpg at best.  Of course, idling for 10 min a day can lower mileage by 2 mpg easily.  With the snow tires on, I average 20 mpg +- 0.3 mpg.

The reason I think my car only does 1 mpg better when your are really nice to it is because the engine is less efficient at the lower hp levels.  If I do 4k rpm every where I go and then coast, I get about 20-22 mpg.

On the other hand, our 01 bmw 740 will go from 29 hwy to 20 hwy if you aren't nice to it, thanks to the v8 and 4450lbs dry weight.

Title: Re: Treadmill Dyno
Post by: taylorp035 on February 24, 2011, 11:26:09 PM
The most noticeable drafting is when you drive our 97 Jeep grand cherokee behind a semi, maybe 30 feet, in which it feels like you are being sucked towards the truck. 

During the summer, my job is about 800 ft in elevation lower than my house, so I can pretty much coast for 11 miles.  Coming back, you have to give it a lot of gas, but I think it is more efficient.  I was able to get 23 mpg on 40 mph roads, which is pretty good.

As for hwy speeds, in the jeep, at 55 on a flat road, you get ~26 mpg.  When you hit 60, it goes down to 22 mpg and at 65, it goes down to 17-18 mpg.  Interestingly, you can get 29 mpg in 2nd, 3rd, or 4th gear going at a steady 25 mph.

I heard that if you take a manual jeep cherokee and do the burn and coast method, you can get 100 mpg.  I don't doubt it in the least.  Having an engine idle so much is such a waste of power.  Supermileage teams who run their engines at 10% throttle for the solid 9.6 miles only get ~ 200 mpg (this has been proven 100+ times).
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 24, 2011, 11:29:51 PM
It's interesting to note however that an automatic transmission alone can suck 20% of an engines power right out of the 'system' on its way through the drive train. This will either translate to less power to the wheels, or less fuel mileage, depending on how you drive.

RP -

Gotta admit, though, 16 -> 23 is a pretty fair amount, particularly being in an automatic. Were you doing any true 'neutral coasting' at all? Not that I recommend it; they say it's hard on an auto to manually shift it (unless its one of these new 'manumatics')...


Taylor -

Strange conflict between the '99 Olds and RP's 93 Deville... They're both in what I call the 'boat' class, particularly the Deville. It's interesting that they're comparable when feathered, but share no ground when 'dogged'. And the Olds is the smaller (and presumably lighter) of the two!

Not sure of the specifics on engine size for either one however, which may play a role in efficiency (sometimes the larger engine IS more efficient). An underpowered engine has to work too hard (and therefore uses more fuel than it would otherwise need to). Same thing happens on the other side - an oversized engine uses more fuel just running, and if all the torque it CAN create is never utilized, the extra fuel usage goes to waste just keeping a stoich mixture. So there is a sweet spot in terms of engine size vs weight and drag...

Definitely a head scratcher and has me wondering a few things.

While I'm pondering over the unknown, I'll throw mine out there - The Camry is a 2.5 4 banger with the variable valve timing... FWIW.

Steve

PS - RP - Love the dog... hahaha that's funny right there, don't care who y'are that's funny! LOL

Title: Re: Treadmill Dyno
Post by: zap on February 24, 2011, 11:36:02 PM
I broke down and bought a UltraGauge back in December... about the time work slowed down to... nada :'(  Because of that I don't have many miles on it yet but it's sure fun to watch the number jump around.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 24, 2011, 11:39:34 PM
I agree completely about the idling. Very wasteful.

My conflict there comes from lubrication concerns.

Toyota (and others now) gets away with it seemingly unscathed in the Prius. That thing cuts off in a heartbeat if it determines that the engine's output is not going to be necessary, and starts up just as readily when it is.

But I worry about what comes down to essentially continuously 'dry-starting' the engine. Most of the wear in an engine takes place during and immediately following cranking, following a settling period where the oil drips away from the parts. Before the oil has built up pressure and has otherwise been sloshed about to lube everything that needs it, there's metal on metal everywhere.

It's half the reason that Diesels last so long - they never shut the friggin things off. Of course using an 'oil' as a fuel doesn't hurt upper cylinder lubrication any either.

I'd like to believe that there's a pre-start electric oil pump that brings the pressure up to value at the very least for the continuous start/stop cycling those engines go through.

It's the one reason that even though my car is a stick, I don't kill the engine with the key during coasts. Too afraid of reduced engine life... ?

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 24, 2011, 11:45:19 PM
Quote
Strange conflict between the '99 Olds and RP's 93 Deville... They're both in what I call the 'boat' class, particularly the Deville. It's interesting that they're comparable when feathered, but share no ground when 'dogged'. And the Olds is the smaller (and presumably lighter) of the two!

It's definitely a boat!  It's really light though, at ~3600 lbs empty.  It has the 3.8L series 2 v-6 engine at 205 hp and 230 ft*lbs.  It rolls really, really well and it is in good running order for a 12 year old car.
The bmw is exactly the same in the dimensions category, but it has 282 hp (probably more like 300), and 325 ft*lbs with the 4.4L v8.  It weighs in at 4450 lbs.  What's different with it is that it uses no gas when you let off the throttle, so it turns the engine over while you coast.  This affects the coasting, but it doesn't really matter.  But, you can keep it below 1500 rpm all day long. People with the v-12's can keep their rpm below 1200.  I remember going to the E.R. once and we hit 105 mph, but the tach didn't even hit 3k rpm  ;D  Nothing like a car meant for the autobahn...

With the whole family piled in on a trip, the bmw would weigh 5500 + lbs, but you could get 31 mpg at 65 mph.  At 55 mph, you can get 38 mpg.

Tomorrow I plan on doing some simple comparison tests between our efi engine and the stock engine.  I will try to keep all of the variables the same (up to running temp, same load, same belt tension...)  We have a 50 cc burret style thing that has a connection for a fuel line, so we should be accurate to 0.1 cc's of gas.  The load should be the same and kept accurate to with in 1% using the volt meter.


Edit:

Quote
It's the one reason that even though my car is a stick, I don't kill the engine with the key during coasts. Too afraid of reduced engine life... ?
Quote

I have turned my car off while coasting down big hills, for maybe 30 seconds at 40 mph.  The downside is you loose your power steering and power brakes, which are nice for those white tailed deer and dodging the monster potholes...

I sometime put it in neutral, but it doesn't seem like it does much, especially since my car idles at ~1000+ rpm.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 25, 2011, 12:01:51 AM
Here are the tires we bought today:

http://smtp.schwalbetires.com/bike_tires/road_tires/kojak (http://smtp.schwalbetires.com/bike_tires/road_tires/kojak)

http://smtp.schwalbetires.com/bike_tires/road_tires/marathon_racer (http://smtp.schwalbetires.com/bike_tires/road_tires/marathon_racer)

We are running 20" x 1.75" rims.

The keys to low rolling resistance are:

radial tires (all bike tires are cross ply)
no tread
high pressure
wider tires


Our tires that we own that have a coefficient of 0.0008 are radials.  They are the only ones in the world and you can't buy them.  The next "best" tires have a coefficient of 0.0024 or 3 times higher because they are cross ply.

I can't wait til they make carbon fiber stranded radial tires with an inflation pressure of 200 psi.  Unfortunately, the tires can actually get too bouncy and cause major problems that cause the tires to "microslip" and cause more friction.  This is especially important when you don't have a suspension.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on February 25, 2011, 12:05:54 AM
Quote
With the whole family piled in on a trip, the bmw would weigh 5500 + lbs, but you could get 31 mpg at 65 mph.  At 55 mph, you can get 38 mpg.

I've noticed fully loaded long trips to be more efficient too... Never really could make heads or tails of it.

Figured it was just because it was completely highway driving that accounted for it, but I'm convinced the added weight plays a role, just not sure how exactly... ?

One of my theories is that the extra weight allows for more kinetic energy to be stored, and at highway speeds, this could be equating to less modulation of the throttle over the inevitably numerous subtle slopes that one encounters on the freeway (speaking in terms of mostly flat terrain).

Mountainous drives are a whole different animal, as you pointed out earlier, and can really throw the numbers if you're not paying close attention to how you're viewing the 'data'.

Quote
The downside is you loose your power steering and power brakes,

Ahh, yes. In the Camry however, the steering is electrically assisted, so as long as I return the ignition switch to the 'run' position, the power steering stays with me. The brakes are assisted electronically somehow as well, at least to some degree, but that's not clear exactly how. The brakes do feel different with the engine running than without, but in the 'accessory' position, the only 'power assist' you have is what you can deliver to your thighs from your arms with both feet on the pedal... LOL Maybe a vacuum pump (not even sure there's a vacuum booster in it though), or something that the ABS modulator does? Dunno... ???

You'd think someone like me would know the car inside and out already, but that part of me somehow lost interest some years back in knowing all the details of the machine as a whole. I think when carburettors died off, they took a piece of me with them.  :'(

Ahh, the good ol' days, when you didn't have to bend over the fender to work on your straight six... Just jump in the engine compartment and stand next to it!  8)

They are gone, however, for good, me thinks.  :-\

Steve

EDIT -

"wider tires" ... ? Seems counterintuitive...
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 25, 2011, 12:11:16 AM
Well, I'll be back hopefully on Saturday night, if not by Sunday.  I'm always open to ideas!
Title: Re: Treadmill Dyno
Post by: Bruce S on February 25, 2011, 11:32:30 AM
Steve;
There is a relationship between the width of the tires and the amount of "micro-slip" or traction.
During winter months, I change my tires ( actually have 2 different sets already on rims) 185/75R14 32psi for winter, 205/70R14 35psi summer.
The narrower tire allows more of the weight of the vehicle to be put towards better traction.
A wider tire, to a point, allows the weight of the vehicle to be spread out.
There is a maximum here too where too wide gets you nothing more than more expense and more slippage due to more tire being on the road leading to less handling.
AND bounce, which is what I generally laugh at when the "hipsters" put those 20" tires on.

Hope that helps;
Bruce S
 
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 26, 2011, 12:13:06 PM
I hadn't thought of the connection between car tires and bike tires like that before Bruce.


Well, I made it it Saturday ;D   Last nights progress was fairly large. Things that we accomplished included:

Wiring up the 3000W of light bulbs on to a nice board.
Adding the 3" v-belt pulleys and belt to the engine
Running the stock engine and getting a small amount of data, which will be presented below.
Sanding and finishing the last bits of the car.
Putting the cooled seat components together and testing them out.
Fixing the bore for the bearing in the rear clutch.
Took lots of pictures and video  :)

Now for some pictures:

The 1 set had 3 bulbs, the 2 sets had 6 bulbs, and the 3sets had 10 bulbs, all wired in parallel.
The voltages are at full throttle and so were the amperage values.  The 3rd amps value was calculated, since our meter was only rated for 10 amps.
The watts was then calculated.  The ohms value was also calculated, so to see if there was any consistency.  It was about 50 ohms per bulb.  The bulbs are 300w.
(http://i51.tinypic.com/2je19fl.jpg)

Here is the load.  There are two switches on the bottom to turn on the last two rows.
It was obvious that the treadmill motor could put more of a load on the engine than was required with all 10 bulbs on.
For a reference, no load voltage at full throttle was about 105v.  The treadmill motor is about 33 rpm / v, but that number may dip a little under load ????
(http://i52.tinypic.com/dzi9on.jpg)

We had to lift the light bulbs off the table, since it was vibrating pretty bad.
(http://i55.tinypic.com/23kp4s6.jpg)


Here are some pictures after the sanding, but before the glue was mixed up.
(http://i51.tinypic.com/mmsmu1.jpg)

(http://i51.tinypic.com/huktoz.jpg)

(http://i52.tinypic.com/33c0rux.jpg)



Title: Re: Treadmill Dyno
Post by: taylorp035 on February 26, 2011, 01:33:27 PM
Here is the first video of the electric dyno in operation.  Later, we added more bulbs.

http://www.youtube.com/watch?v=dErZDp20kSM (http://www.youtube.com/watch?v=dErZDp20kSM)
Title: Re: Treadmill Dyno
Post by: zap on February 26, 2011, 02:14:49 PM
Nice video... you boys are having way to much fun!

924 watts =1.2hp?  How warm is the treadmill motor getting?

Once again... thanks for all the info you keep providing.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 26, 2011, 03:19:20 PM
Here was the original set up with the chain.  It was getting really jumpy around 60v.

http://www.youtube.com/watch?v=5OIXyeXDMhw (http://www.youtube.com/watch?v=5OIXyeXDMhw)

Quote
Nice video... you boys are having way to much fun!

924 watts =1.2hp?  How warm is the treadmill motor getting?

Once again... thanks for all the info you keep providing.

We always have a lot of fun!  Several of the videos I will not post because something distracting happens or something goes wrong.

As for the the 924 watts, I believe the governor is way too low.  If the top rpm was only 105*33 = 3465 rpm, then it is set too low.  I know we hit at least 5,000 rpm last year in competition.  The data with the engine suggests a max rpm of 4000 rpm for extend run times.  Peak torque is supposed to be 4.9 ft*lbs at 2800 rpm.

Here is the official data:
http://www.jackssmallengines.com/bs35horizontal.html (http://www.jackssmallengines.com/bs35horizontal.html)

Also, the belt was getting pretty warm, so I bet it was only 90-95% efficient.  As for the motor, I ran it at full throttle for probably 5 minutes and it wasn't cold anymore, but it wasn't hot, maybe 90 F.

I am wondering what the efficiency of the treadmill motor is.  Maybe we will hook up another electric motor to the treadmill motor and see what we can figure out.  Does anyone one have any data on this?


EDIT:  Also, would any one know if the torque required for the treadmill motor is an quadratic function?



Title: Re: Treadmill Dyno
Post by: taylorp035 on February 26, 2011, 10:24:31 PM
Here is the last video, with all 10 light bulbs. Sorry it took me so long to upload it...

http://www.youtube.com/watch?v=0y64QiC9mkA (http://www.youtube.com/watch?v=0y64QiC9mkA)

The output was between 67-69v @ a calculated 13.6 amps. The rpm was only about 2200, so it was obvious that the treadmill motor was winning the torque contest.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 27, 2011, 05:19:14 PM
I have been thinking about how I am going to find the absolute efficiency of our engines.  It will be easy to compare the fuel usages between the engines at a set power and rpm level, but actually getting a percentage is going to be difficult.

Idea #1 would be to take the hp graph from the manufacturer and compare it to the fuel usage.  This would only be accurate if our engine actually puts out what its supposed to.

Idea #2 would be to do what the wind folks do around here and make a lever arm scale thing that measures the torque.  This would only be as accurate as the scale reading * the rpm accuracy.  I'm not sure how I would find the torque, since both the engine and the motor would need to be clamped down to a table.

Idea #3 is to try to calculate the efficiency by comparing it to last year's results.  This would be an average efficiency, which isn't what I want, but it would work.  According to the numbers, it should be between 9-10% efficient, which I am fairly confident about.

Any ideas out there that I could do to find the efficiency?

Title: Re: Treadmill Dyno
Post by: SparWeb on February 27, 2011, 05:46:26 PM
Got a lathe?

On my pages, look for the alternators, the Baldor conversion, and near the end is the load test.
www.sparweb.ca

It's really really that simple.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 27, 2011, 06:02:39 PM
Well, I have the exact same scale, but the lathe may be a little tricky.  Mine at home wouldn't have enough power or clearance and the one in our lab is way too small.  We could use our mill, but I would have to put the motor in a 3 jaw jacobs chuck.  Maybe I should put it in a 5/8" collet instead.  I don't remember the hp rating on the mill, but it's 240v, so probably at least 3 hp.  The same mill at my high school had a 10hp motor.


Title: Re: Treadmill Dyno
Post by: SparWeb on February 27, 2011, 06:26:21 PM
I watched a couple of your team videos to see how you're set up.
If the vertical mill doesn't work, you could rig up with the engine test bench you already have.  I think so at least - it would take some fabricating of a mount for the electric motor that allows it to rotate freely...  It will take some though to set it up right, but it seems like a mount for the motor like a baby cradle, whose axis is co-axial to the motor shaft would permit freedom to rotate the motor, yet keep the motor properly aligned to the motor.  Its freedom to rotate is resisted by the long-beam.  I can't tell if that came across clearly in words so just write back after trying the milling machine, if you want another option.
Depends on how badly you want the numbers.
Title: Re: Treadmill Dyno
Post by: SparWeb on February 27, 2011, 06:27:23 PM
Oh yeah (duh) the other way is to prony-brake the B+S motor of course!
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 27, 2011, 06:50:55 PM
Well, we have the water break for the dyno and it is all set up and working  BUT, the water break is so uncontrollable that it will just stall out the engine and no data can be taken.  Putting the motor in the mill will be far the best option.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 03, 2011, 08:14:04 PM
Today I had a little time to mess with the dyno, so I hooked up our new analog 30 amp meter to the light bulbs.  I also hot glued all of the loose wires and things.  We maxed out  (with the governor) at 66 volts @ 16.5-17 amps.  This means there was about 2 hp at the shaft of the engine.  Interestingly, this is about 25% higher than we predicted using ohm's law.  I measured the bulbs with the multimeter today and it said 4.6 ohms, but when we do the calculations, they should be about 50 ohms.  I imagine the resistance goes up as the filaments heat up.

Tomorrow is the fun day, where we will hook up the burret to the gas line and take the governor off.  I will have to see how warm the treadmill motor gets, especially  when generating 20-30 amps for several minutes.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 05, 2011, 03:39:20 PM
Hi guys, I know you guys have been waiting patiently for some results, so here they are.  I have 3 videos that really show how the whole thing is set up, the last one is still uploading.  I will get you some data, graphs, and temps of the treadmill motor in ~2hrs.

http://www.youtube.com/watch?v=6NPW412Fi1s (http://www.youtube.com/watch?v=6NPW412Fi1s)

http://www.youtube.com/watch?v=nPyQXx92IFM (http://www.youtube.com/watch?v=nPyQXx92IFM)

and here is the 3rd video:

http://www.youtube.com/watch?v=0Y3JSa3i5HI (http://www.youtube.com/watch?v=0Y3JSa3i5HI)



EDIT:

Q:  Does the motor get hot and under what loads?

Well, we ran the engine for about 2 hr's straight at full throttle with approximately 1 minute breaks between 2-3 min long runs.  Even after a good 1/2 hr of generating 800-1000 watts, the motor was in the 110-130 degree range.  There is no fan on this motor to cool it down. 

Q:  How much power can you get out of the treadmill motor?

Haven't found the upper limit yet.  Our highest data point was at 75v @ 17.4 amps = 1305 watts, which represents 10 -300 watt light bulbs with the stock engine past the governor.

Q:  What efficiencies did we achieve?

We don't know the efficiency of the treadmill motor or the v-belt, but I assumed a constant 80% for the motor and 95% on the belt.  This comes out to 76%.

If you assume the constant 76%, the engine peaked at ~14.2% efficient + or - 0.2%.  Below or an another post, I will copy my table of data for you guys to see.

Q:  How was efficiency calculated?

The dyno was set up with the engine and the treadmill motor connected with 3" pulleys and a v-belt.  The gas was measured using a 50 cc buret connected.  What we did was we filled the buret past the top with fuel and then we started the engine.  When the fuel passed the "0" mark, we started the stop watch, and we stopped the timer after it passed the 30 cc mark.  This allowed us to get very accurate measurements, within 0.5% roughly.  While it was running, we observed the voltage and the amperage.  The data was then put into an excel sheet where all of the necessary conversions and calculations were made. 

Q:  Were the results repeatable? 

Yes,  we could do the same run several times in a row and only have variations like these -->   0.1393, 0.1431, 0.1386, 0.1414.   Usually the runs were even closer than this.

Q:  What is next to do?

Find the efficiency curve of the treadmill motor by using the vertical mill with a scale or a torque cell.  Also, I would like to get at least a few data points from the EFI engine, even if it is really hard to control.  Visual observations from the few test runs with the EFI engine showed that it really likes to guzzle gas, but nothing has been proven yet.



Title: Re: Treadmill Dyno
Post by: taylorp035 on March 05, 2011, 05:43:36 PM
Volts     
92
89
91.2
91.2
92
65.5
77.5
78.5
78
78
63.5
63
66.7
66.5
69.8
69.2
73
71
75.9
79.5
79.5
83.5
88
87.5
92
91.6
96.7
96.4
96.5
100.8
75
53.6
62
44.7
43.7
Amps   
6
5.9
5.8
5.8
5.9
5.1
10.7
10.7
10.7
10.7
16.2
16.1
15
15
13.7
13.7
12.1
12.1
10.7
9.1
9.1
7.4
7.8
7.8
6
6
4.1
4.1
4.1
2
17.4
15
15.2
13.7
13.4
Watts   
552
525.1
528.96
528.96
542.8
334.05
829.25
839.95
834.6
834.6
1028.7
1014.3
1000.5
997.5
956.26
948.04
883.3
859.1
812.13
723.45
723.45
617.9
686.4
682.5
552
549.6
396.47
395.24
395.65
201.6
1305
804
942.4
612.39
585.58
Gallons               
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
0.007925162
Seconds   
160.22
187.64
165.05
174.87
161.79
248.25
133.57
135.47
132.11
134.76
110.2
110.32
114.58
113.97
115.81
115.24
120.11
122.76
128.84
141.81
138.94
148.97
140.75
145.64
159.05
159.74
177.1
177.94
178.76
201.2

134.77
116.5
169.59
163.75
Joules/s               
6529.280526
5575.150959
6338.208579
5982.280128
6465.920798
4213.983186
7832.00813
7722.162294
7918.562758
7762.847476
9492.933992
9482.608103
9130.051719
9178.918364
9033.082859
9077.762287
8709.69383
8521.679097
8119.538388
7376.922121
7529.302763
7022.362395
7432.478337
7182.925885
6577.311071
6548.90025
5906.952716
5879.067809
5852.099608
5199.410169
#DIV/0!
7762.271469
8979.582197
6168.531906
6388.527181
Est. RPM
3036
2937
3009.6
3009.6
3036
2161.5
2557.5
2590.5
2574
2574
2095.5
2079
2201.1
2194.5
2303.4
2283.6
2409
2343
2504.7
2623.5
2623.5
2755.5
2904
2887.5
3036
3022.8
3191.1
3181.2
3184.5
3326.4
2475
1768.8
2046
1475.1
1442.1
Efficiency       
0.111239789
0.123928672
0.109810208
0.116343599
0.110457667
0.10430499
0.139315282
0.143120194
0.138681466
0.141463284
0.142585278
0.140742425
0.14418838
0.142990704
0.139292074
0.137415038
0.133441756
0.132649296
0.131607495
0.129038626
0.126427098
0.115776753
0.121515039
0.125022356
0.110427465
0.110424326
0.08831475
0.088458349
0.088958176
0.051017933
#DIV/0!
0.136286748
0.138091057
0.130626919
0.120606828
Shaft HP       
0.974006656
0.926541477
0.933352465
0.933352465
0.957773212
0.589432832
1.463215615
1.482095817
1.472655716
1.472655716
1.8151461
1.789737231
1.765387064
1.76009355
1.687325371
1.672821142
1.5585871
1.515886084
1.433007293
1.276531006
1.276531006
1.090287523
1.211156103
1.204274534
0.974006656
0.969771845
0.699573223
0.697402882
0.698126329
0.35572417
2.302678779
1.418661869
1.662869335
1.080565102
1.033258728
Notes 
Full Bunny, 3 Lights
Full Bunny, 3 Lights
Full Bunny, 3 Lights
Full Bunny, 3 Lights
Full Bunny, 3 Lights
Partial Throttle, 3 Lights
Fully Bunny, 6 Lights
Fully Bunny, 6 Lights
Fully Bunny, 6 Lights
Fully Bunny, 6 Lights
Full Bunny, 10 Lights
Full Bunny, 10 Lights
Full Bunny, 9 Lights
Full Bunny, 9 Lights
Full Bunny, 8 Lights
Full Bunny, 8 Lights
Full Bunny, 7 Lights
Full Bunny, 7 Lights
Full Bunny, 6 Lights
Full Bunny, 5 Lights
Full Bunny, 5 Lights
Full Bunny, 4 Lights
Full Bunny, 4 Lights
Full Bunny, 4 Lights
Full Bunny, 3 Lights
Full Bunny, 3 Lights
Full Bunny, 2 Lights
Full Bunny, 2 Lights
Full Bunny, 2 Lights
Full Bunny, 1 Lights
Full Throttle, 10 Lights
Partial Throttle, 10 Lights
Partial Throttle, 10 Lights
Partial Throttle, 10 Lights
Partial Throttle, 10 Lights
[/td][/tr][/table][/td][/tr][/table]


Note:  These graphs have not been corrected for the efficiency of the treadmill motor or the actual rpm.  The rpm is based on a steady 33 rpm / volt.

(http://i52.tinypic.com/dcygs9.png)
(http://i56.tinypic.com/es4w7k.png)
(http://i53.tinypic.com/2mmu2va.png)
(http://i56.tinypic.com/15ezl2w.png)


Some things to notice:

The efficiency went down as the voltage went up.  This is due to the higher rpms could only be achieved with a smaller load, which is less efficient.
Only 5 tests were done at partial throttle.  More of these tests would make the results better.


EDIT:
Here are some more things I found:

(http://i55.tinypic.com/2crkm4y.png)
(http://i51.tinypic.com/noeur4.png)

The 5 points that are not on the voltage vs torque curve were the partial throttle runs

(http://i54.tinypic.com/2uiaqt0.png)
Title: Re: Treadmill Dyno
Post by: SparWeb on March 05, 2011, 11:47:21 PM
First I have to say this is a lot of work! 

I have to ask about the ~15-20% efficiency, though.  Going back to this one:

(http://i56.tinypic.com/es4w7k.png)

Am I seeing the high-RPM end of the engine's efficiency curve?  Is the efficiency of the engine alone represented here, or is it engine efficiency X the motor's efficiency?

The reason I ask is that I did tests like these ones in college (mighta mentioned before) and though it was a V-8 Ford, I wouldn't expect the B&S engine to be THAT BAD.  The Ford had a volumetric efficiency peaking in the 70's (IIRC! it was a long time ago))  and the mechanical efficiency was around 50-60%.  Do I remember that wrong, or is the difference between a V-8 and a 1-cylinder engine that great?

It would make more sense if we were looking at 40% (engine) X 40% (motor) = 16% efficiency of the two coupled together.  (or some variation of their proportions leading to the same result).

Is this with or without all the engine mods you told us about last month?

What happened on the data line, fifth from last?
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 06, 2011, 12:25:53 AM
Quote
What happened on the data line, fifth from last?
That was our peak power on the stock engine.  I had to manually hold the throttle wide open so the governor wouldn't slow the engine down, hence there is no time value for it. 

Quote
Is this with or without all the engine mods you told us about last month?
100% Stock, less than 1 hour of run time on the engine.

Quote
It would make more sense if we were looking at 40% (engine) X 40% (motor) = 16% efficiency of the two coupled together.  (or some variation of their proportions leading to the same result).
The efficiency value you see is the calculated engine efficiency, including the losses from the treadmill motor @ 76% efficient.  The calculation is really more like (Watts measured / 0.76) / power in gasoline.

And yes, the Briggs engine is that bad.  The number is probably closer to 12% peak efficiency b/c I think my 76% for the treadmill should be closer to 85% * 95% = 80.75%.
The reason it's so bad is because it is an "L-Head" design, instead of an overhead cam.  Also, the compression ratio is kinda low, so thermodynamic efficiency could be higher.




Title: Re: Treadmill Dyno
Post by: taylorp035 on March 07, 2011, 10:24:01 PM
On Wednesday, there are some serious plans to figure out the efficiency of the treadmill motor.  I will try to get some lower rpm readings so the wind community can utilize the data.

I would like to answer several questions which include:

Is the RPM / Volt a real constant, or does it vary with current or rpm? [with a load like light bulbs, not batteries]
Does the efficiency change over the rpm range, voltage range, current range, or a combination of the three?
What is the loss in the bearings and v-belt?

I hope to remember to use the Doc Watson meter for the lower power levels so I can get more accurate power readings.  Maybe I will do both, so I can figure out my error in my previous readings.

Once I am done with all of this, I will take the data and make a real engine efficiency curve, which then can be put directly into my mpg calculator.  I am also considering putting the data into last year's data, so I can compare the results of my excel sheet with some real life numbers and possibly explain why we got 777 mpg on our 4th run instead of the 630,650,698 on the other runs.  I have some strong suspicions to why this is (engine has a low efficiency at the top rpm, which the 777 run was conducted by someone who was going 2 mph slower at the top speed).  The scary part is, 2 mph is all that it takes to drop 100 mpg.  That will double to 200 mpg with this year's car.


Title: Re: Treadmill Dyno
Post by: taylorp035 on March 10, 2011, 03:24:42 PM
Yesterday I tested the efficiency of the treadmill motor on the vertical mill, using a torque arm set up and a scale.  I also got some corrected RPM/v values, which are mighty important.  Unfortunately, we did not have a good way to measure the rpm (even the oscilloscope was tried), so obviously the mill was running slower under load than the nameplate said.  If I had the rpm values, I could of calculated the efficiency in ~5 minutes on excel, but instead it took me 4 hours.  But, I did some cross referencing of my results to make sure they were accurate across the rpm and hp ranges.  The end result came out to something like this:

(http://i53.tinypic.com/166xksx.png)


(http://i52.tinypic.com/nv9sf6.png)
Title: Re: Treadmill Dyno
Post by: SparWeb on March 14, 2011, 02:20:56 PM
.....  Unfortunately, we did not have a good way to measure the rpm (even the oscilloscope was tried), so obviously the mill was running slower under load

Bike speedometer?   Oh well I'm sure it's close enough.  The curve hasn't changed much since the last version, so presumably further refinements won't do much good.
Isn't it nice to have a project like this with nobody looking over your shoulder asking "what are the sources of uncertainty?".   :-\
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 15, 2011, 01:31:28 PM
Quote
Isn't it nice to have a project like this with nobody looking over your shoulder asking "what are the sources of uncertainty?".
Yeah, I just finished a Physics lab course on optics and nuclear stuff, which we spent hours and hours figuring that stuff out.

In the last few minutes, we just found a paint shop who is really excited to give us a paint job on the car.

Earlier today, I hooked up our new box fan to our cooled seat, and I set a new record of 50.77 F, which is really cold when you sit on it.  I then hooked about 40' of 1/2" tubing to the whole system and a reservoir of about 1/4 gallon and turned it on.  It got down to 63F using about 140w of power.  I then put the tubing on a chair and sat on it for 5 min.  It was very effective.

Got to run!

Title: Re: Treadmill Dyno
Post by: Bruce S on March 15, 2011, 03:36:20 PM
Of course you know we're going to ask for a separate post on just the cooling setup of the seat.
I will certainly start the official request  ;D
Thanks
Bruce S
 
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 16, 2011, 09:30:47 PM
Oh, don't worry, I was kinda adding my knowledge to a thread in the heating section with the mini fridge.

http://fieldlines.com/board/index.php/topic,144978.54.html (http://fieldlines.com/board/index.php/topic,144978.54.html)

I hope to make a new thread when I get some time and new photos + optimize the section.

I was thinking that this could replace an air conditioner in some one's house, so you only have to cool a seat.  The parts can be bought relatively cheap ($10 for the chip, $12 for the heatsink, $3 for some thermal grease, $20 for some nice rubber tubing, and a water pump good for 1-2 gpm.


As for the car, the paint place is going to do an awesome job (they want it to look nice), so they said they would do the filling and sanding for us (the worst part).  More on this next week when we go back to discuss things in more detail.

To get the car to the place, we shoved the car tail first into a mini van.  The tail was resting on the arm rests of the front seats and it barely fit.  Looks like we will need the extended wheel base minivan to get it to MI.


Title: Re: Treadmill Dyno
Post by: taylorp035 on March 22, 2011, 11:42:53 PM
We officially gave the car away today for ~ 3-5 weeks to the paint shop.  We are unhappy that it will take so long, but it would of taken us at least 5 weeks of our own time to do it, so I guess we shouldn't complain.  Anyways, we can finish everything else without the car, like the large amount of wiring (bought a fuse board with powerpole connectors on it).  I may also wire up another "Y" to the battery connection so I can hook up 3 batteries instead of 2.  We will also program the computer and install it on the wheel skirt.  Also, the cooled seat will be finished (a carbon fiber air duct, a carbon fiber cup holder ;D ;D ;D , the cushion that the tubes run through, and the power switches).  Also have to wiring up the kill switches (I think 4-5 ), plus the master key(snowblower key) and master kill switch.

The dashboard will have to be designed and made, which will have to hold a bunch of switches, the 7" screen, a Doc Watson meter, and maybe an air/fuel mixture gauge.  The steering will be finished and the plate clutch will be connected to the big gear via a keyslot.  Last Friday I spent 2 hours taking of 0.002" off the 6 diameters on the rear axle with sand paper and a file.

Lastly, we will have to swap the brushless starter motor + custom flywheel off the EFI engine on to a stock engine.  We will have to rig up an ignition system somehow since there will be no magneto.

Sorry for the scrambled post.  More updates to come ;)



Title: Re: Treadmill Dyno
Post by: SparWeb on March 23, 2011, 12:05:54 AM
... a carbon fiber cup holder ...

It's not the refrigeration system that makes your car cool...!
Title: Re: Treadmill Dyno
Post by: zap on March 23, 2011, 12:38:49 AM
I can't seem to wrap my head around the "3-5 weeks" for paint! ???  It's such a tiny vehicle... and I would think not a lot of paint would be applied?

A 747 has about a 2 week turn-around for painting.
... more useless facts:
The average paint job on a 747 is around 600 lbs of paint.
A bare polished 747(my personal favorite for almost any aluminum skinned plane), with customer markings, has about 25 lbs of paint.
It generally costs more to operate a bare polished plane.
(http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html (http://www.boeing.com/commercial/aeromagazine/aero_05/textonly/fo01txt.html))

"4 minutes to paint a 747"
http://www.boingboing.net/2010/12/13/13-day-boeing-747-re.html (http://www.boingboing.net/2010/12/13/13-day-boeing-747-re.html)
Title: Re: Treadmill Dyno
Post by: Bruce S on March 23, 2011, 09:09:01 AM
ZAP;
 I'm thinking it's the prep time to get the carbon fiber body nice & smooth then to layer up the paint with time in between to wet sand the body paint to get it back to smooth.
I'm looking forward to seeing how it looks.

Taylorp035,
What would have been neat to know, what did the car weigh before it went to the paint shop, then weight it afterwards  ;)

Thanks for the update, it does sound like you have a fair bit of work while the car is in the shop.
Are they going to have photos of the before , during and finish of the car?
That would be cool to see too.
Cheers
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 23, 2011, 05:19:27 PM
The large amount of time will be because they have to sand it, fill it, sand it, repair any holes, sand it, paint two colors, clear coat it, and maybe a rally stripe.  Also b/c they are doing it for free.

As for weight, I don't have a clue.  It shouldn't be much.  The weight of the car was changing every week.  It should of been close to 40 lbs with nothing in it.

Title: Re: Treadmill Dyno
Post by: taylorp035 on March 26, 2011, 01:53:13 PM
After about 4 hours of running the EFI engine with the computer hooked up to it, there were some obvious things that were wrong, like the displacement (changed from 350cc to 150cc).  It was also obvious that it had never been tuned with a load on it, since it ran really nice with no load, but once we added 1/2-1 hp of load, it would stall out.  After a few minutes with the auto-tuner turned on, the performance was greatly increased.  We didn't do an efficiency run yet, but we were able to push 4,000 rpm with 5-6 lightbulbs, which translates to 1-5 to 2 hp at the shaft, at about 50-80% throttle.  With a bit more time, I bet we can tune the higher throttle levels with 8-10 lightbulbs and get 3 hp at the shaft.  As a reference, we measured the stock engine at 1.8 hp at the shaft.

Unfortunately, the engine gets harder and harder to start after you run it, which makes absolutely no sense.  Oddly though, a stock engine has the same exact problem.  Maybe something is expanding and a valve is not fitting?  It is an air cooled engine, and we were measuring temps past 260 F.

The starter motor held up very well, especially since we must of started it 200+ times, most of those with no clutch and hooked up to the treadmill motor.  We used the 30c 1350 mah 4s lipo batteries, which worked better than the 4s A123 pack.

In a about an hour, I will post a short video.

EDIT:
http://www.youtube.com/watch?v=cWUIFrfvJxk
Title: Re: Treadmill Dyno
Post by: zap on March 27, 2011, 12:19:21 AM
How much do you think you're losing with that belt flapping like it is?
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 27, 2011, 12:48:41 AM
Quote
How much do you think you're losing with that belt flapping like it is?

I was wondering that my self.  When we had the chain on there and it started to bounce, it would suck almost all of the power.  But with the belt, I don't really notice a difference.  At slow speeds (<1500 rpm), you can easily see the jerking caused by the single cylinder.  No matter how tight we make it, it still bounces.  In my calculations, I was guessing 95%. 

Next time we run the engine, I hope to get a few more efficiency numbers, tune the engine for full power, and get a max hp number.  The stock is good for 1.7 hp with the governor, probably 2-2.2 hp with out it.  I bet the EFI could do 3 hp.  I also hope to re-calibrate my volts vs. rpm, since the computer puts out the rpm, especially under load.

If next year we decide to use the same body but a different engine, we will do a thorough analysis of the treadmill motor, belt efficiency, chain efficiency, and engine efficiencies.
Title: Re: Treadmill Dyno
Post by: RP on March 27, 2011, 01:07:23 AM
Does that engine have a cast iron or cast aluminum flywheel?  If it's aluminum then that may be why the pulsation is so strong.

Can you borrow a stroboscope?  That's a xenon strobe with an adjustable flash rate.  You could use that to sync to the engine rpm and see if the belt flapping is some kind of self resonance or if it's truly tied to the power stroke of the engine.
Title: Re: Treadmill Dyno
Post by: zap on March 27, 2011, 11:53:10 AM
I've thought about this and it seems to me that even if you put a tensioner on the belt, even though you might lessen the amount of "flop", you wouldn't gain much of anything back.
I'm thinking that the amount of energy you gained (if any) by reducing "flop" would more or less be lost to the added friction of the tensioner, if it was spring loaded, then also there would be energy lost in compressing the spring, and even if it didn't have a spring then energy would be lost in stretching and re-stretching the belt.

If you look at the belt all by itself, it doesn't seem like it would take much energy to "flop" the belt back and forth like that?

Yes?  No??
???  ???  ???
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 27, 2011, 05:03:32 PM
Quote
Does that engine have a cast iron or cast aluminum flywheel?  If it's aluminum then that may be why the pulsation is so strong.

Yes, it is aluminum.   The original was cast iron, which weighed 6 lbs.  We then made our own aluminum, which was really just a 99 tooth starter gear, so it only weighs 1.8 lbs.

Quote
If you look at the belt all by itself, it doesn't seem like it would take much energy to "flop" the belt back and forth like that?

Yes?  No??
Huh  Huh  Huh

I wouldn't think so.

A tensioner sounds like a really bad idea.  Maybe we should hook the treadmill motor straight to the shaft and see what happens.  Then you eliminate all transmission losses and uncertainties.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on March 27, 2011, 10:43:22 PM
EDIT - Came back on my computer (rather than phone) to add more to this...

That uber light flywheel is probably to blame for most of what you're seeing... From what I could tell in the video, the engine is struggling just to stay running. The dwell pegging like that is a solid confirmation in my mind for this if I interpreted what I saw correctly. This would correspond with the shaft slowing down significantly at the end of the compression stroke. It sounds like it's misfiring a little too, also an indicator.

Take a typical 3.5HP lawnmower and drop the blade off of it and watch the fight it puts up (if you can get it started at all). I ran across this many years ago and had also underestimated the need for sufficient flyweight when I was trying to convert a vertical shaft over to a horizontal to use in a go kart. The aluminum flywheel on a vertical shaft just isn't enough to provide adequate flyweight to allow the engine to run smoothly.

You're probably already aware of this, but just in case, think in terms of a stick vs automatic in a car. It's not always immediately obvious as to why, but the flywheel is much heavier on the stick because in the automatic, the torque converter provides the supplemental flyweight needed to smooth out the engine's operation.

I would be willing to bet that if you threw those other 5 pounds on the shaft in the right places, all of the erratic behavior you're seeing would go away for the most part. You'll more than likely also see an increase in torque and/or horsepower over what you've been getting out of it.

The weight savings really isn't worth the performance hit that running an underweight flywheel brings IMO. Then again, since you're doing serious pulse and glide, this is going to be a tricky tradeoff.

If you agree and think that the flywheel is playing a role in this and you haven't modified the engine to the point where the original flywheel can't be used, swap them out and see if that brings it 'back to life'.

FWIW

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 28, 2011, 12:07:32 PM
Well, the we can't use the original flywheel b/c of the position sensor (mounted on the back of the ring gear).  We will add the clutch to it, which may help a little.  Last year's car ran pretty nice with the same weight flywheel (a stock aluminum flywheel).  But, when you hit the throttle, it was like riding in a space shuttle (lots of shaking and noise), and it sounded like it too.  Almost if you were in a school bus with 3000 hp doing a 1/4 mile.

This Friday for sure, we will do some more testing and observing to see what we can do.  You are right that the engine is misfiring, mostly caused IMO by the position sensor missing the location.  It was also determined that we had the engine way too hot, since there was no air cooling and we were running it pretty hard.  Temps on the head were past 260 F.  Our temp sensor hooked to the computer maxes out at 215 and we suspect there some settings in the management software that are wrong.

On the plus side, we have an awesome starter motor  :)   built and designed by me with awesome sauce.  We are starting it with a 530 kv 800W Himax brushless out-runner motor meant for model airplanes.  Hooked up to it is a 75 amp Castle Creations ICE controller and a 4s 14.8v 1350 mah LiPo battery, good for 30c.  With a 99:16 gear ratio, it gets the engine up to 950-1000 rpm in no time.  According to the controller, we average 300w while cranking.  If the engine doesn't turn over for some odd reason, it peaks around 100-110 amps.  We are thinking about boosting it to 26v, but the bendex / axle / gear may blow to bits.  Good thing we have extras.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 12, 2011, 05:16:32 PM
Back from the hiatus. 

We figured out why the EFI engine wasn't working.  It turns out that we wired a sensor up backwards, probably due to the fact that we had been awake for ~20 hrs straight.  Once we got it hooked up right, the engine ran decently.  The amazing part is how fast the thing revs.  We could go from 2k to 4k rpm almost as fast as I could push the throttle.  This is probably due to the 1.8 lb flywheel and no load.

No word from the paint shop, but we got the rest of our parts ordered.  Also, we officially finished the rear axle, which has 8 things attached to it on the 6 diameters....

We also broke in our brand new engine by dropping it on the ground ;D  Good thing we throw away the sheet metal.  Turns out that briggs and stratton modified the design a bit by adding ball bearings instead of bushings on the crankshaft and the head is a little different.  Hence we will have to put it on the dyno and try it out.

Now that we have the sensor working, we could try the electronic ignition again on a carbed engine.  Granted, the sensor is extremely picky, but it would be the easiest to build.  Last friday we bought ourselves a set of points just in case none of this works.

The cooled seat is coming along.  Final assembly should happen this friday, along with the carbon fibering of the cup holder.  The decision to not use aluminum tubing for the seat was made because our real world test showed that it was literally like laying on some aluminum round stock  ::) , no matter how soft the foam was. 

Our battery charger and batteries have held up well so far, especially after cranking the engine over for 4 hours and running them past their recommended low voltages.  I tried charging two packs in parallel with balancing wires, but I couldn't get the charger to recognize them both.  The charger is good for 36v and 30 amps and has up to 10s balancing wires.  It is a 3010b iCharger.


I don't have any new pictures, but more should come after next weeks meeting, especially of the rear axle, cooled seat, and engine.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on April 12, 2011, 06:04:01 PM
Sounds good...

One thing though; I'm envisioning "LiPo" and "below recommended voltage" in the same vicinity of each other...

LiPos get cranky when abused.  :o

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 13, 2011, 11:50:37 AM
Yeah, I know.  I need to set the low voltage cut-offs to ~11v on the 4s lipo packs, and ~10v on the starter batteries.  I plan on having a doc wattson meter on the dashboard to monitor the main battery voltage, especially when the cooled seat is running.

I had a 3s2p A123 pack explode on me in my battlebot bot once.  The culprit was over charging the pack to 5v per cell (using a nicd charger... oops).  Then about a week later, I was doing a stress test with the same battery by spinning our weapon up to ~8k rpm and then braking full hard to 0 rpm several times in a row.  We got our 10 gauge wire hot and the 3 strands of 12 gauge in parallel were toasty.  Probably pulling 200+ amps at 8-10 volts.   It sounded just like a lawnmower backfiring.  Then I noticed the spraypaint smell and knew that something was wrong.  Eventually, all 6 cells popped their seals.  All documented in this video:
http://www.youtube.com/watch?v=c5GrG7m-x2Q (http://www.youtube.com/watch?v=c5GrG7m-x2Q)

Title: Re: Treadmill Dyno
Post by: taylorp035 on April 16, 2011, 04:29:14 PM
I just had an excellent idea for my supermileage car, but I need a little help. 

Our special bicycle tires can be run in a tubeless configuration, but we currently only own non- tubeless rims.  I found some products out there that will basically seal over all of the holes.  I was wondering if anyone had some experience with this?

The reason a want to do this is because the tubes substantially increase our rolling resistance.  According to Michelin, it actually goes up by a factor of 3, so this is a rather important issue.


And on a different note, the EFI engine plan has been officially been axed.  After running it a few more times last friday, the efficiency was in the 7-10% range, which is lower than the 13% on the stock engine.  We then pulled the injector off the engine and added a carburetor.  The result was a fireworks show coming from the exhaust and air intake.  We think more gas was blown out the intake than burned in the cylinder....  Next week we are getting an oscilloscope with an attachment to read the spark plug wire to determine if the problem is the spark or the engine.  It is possible that the engine was damaged, especially after taking a temp reading around the spark plug of 415 F  :o  We took the head off after this reading and found nothing wrong, but we don't know very much about engines.


Also, the cup holder and air duct were carbon fibered, so when the car gets back, everything will go in it quickly.

The paint shop was contacted and they reassured us that it would be back by the end of the month. 
Title: Re: Treadmill Dyno
Post by: Madscientist267 on April 16, 2011, 05:24:52 PM
Sounds like at the very least you've got some valve damage of some sort, or a timing issue. Hard to say with a brief description.

Compression check?

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 16, 2011, 06:25:55 PM
Some of the details that I could put in words...
The engine seemed like it was only firing every other time (every 4 revolutions).  For about 2 seconds, it once fired properly.
Also, when messing with the spark advance, we were able get it to run reliably once we got the spark advance to ~1-3 degrees before TDC when below 1800 rpm and ~4.5 degrees at 2200 rpm.  At full throttle with no load, it would max out at 2400 rpm.
Also, I would rotate the flywheel 1/2 a turn before every start so the starter motor could get past the compression stroke.  When I did this, it would sometime fire.... tried to take my hand off about 3 times.

Title: Re: Treadmill Dyno
Post by: Madscientist267 on April 16, 2011, 06:41:24 PM
Not sure exactly what, but something is definitely wrong.

The fiery ports indicate valve leakage and/or timing, and this may be compounded by additional compression loss from a warped head (415F? ouch)...

Don't forget that there are two timings; valve and spark. They can have similar behaviors sometimes depending on how close to 'dead-on' (but not quite) they are.

Compression check would be the first thing I would go after.

Also check for distortions in the valve stems. B&S as I recall uses a fairly close tolerance, which isn't 'adjustable', but may have grown shorter due to overheating.

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 16, 2011, 07:29:40 PM
Thanks for the advice.  We will definitely try it on a less abused block.  I will also get the expert opinion from our adviser. 

When running the EFI engine a few weeks/months ago, the temp would only get to ~275 F, even after running it at full throttle for 1/2 hr.
Title: Re: Treadmill Dyno
Post by: REdiculous on April 16, 2011, 08:22:33 PM
What tires are you running and what size? Steel or aluminum rims? What 'products' did you find?

I think I'd probably try rubber cement to fill the holes since you could glob it on thick and still have enough to go around. If you air up while the glue is still tacky maybe the pressure might push it into the holes a little?..

I'm running a pair of 20x1 3/8 street tires w/ tubes on my bike and with enough pressure I can coast for a looong time. I usually over-inflate by at least 5 psi - harder ride and greater chance of failure but it's worth it. I didn't realize no-tube would be that much better.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 16, 2011, 08:42:45 PM
http://www.chainreactioncycles.com/Models.aspx?ModelID=18703 (http://www.chainreactioncycles.com/Models.aspx?ModelID=18703)

We are running 20" x 1.75" rims, made out of aluminum.  The brand name is Stollen.
I would like to have some carbon fiber rims that are tubeless, but I bet they are super rare in 20" form.

The front two tires are these.  Click on the Michelin link.  We have the expensive tires.
http://www.eshopsem.com/ (http://www.eshopsem.com/)

According to several sources, if you go tubeless and pump them to 6 bar(88 psi), the rolling resistance goes down to a tiny 0.0008 coefficient.  If you have tubes, it goes to about 0.0024, but I have no proof of that.

Last year we ran a paper thin Michelin tires.  We pumped them to 50 psi.  Later we found out that they were good for 73 psi.

For comparison, most normal bike tires have a rolling coefficient of about 0.006.

The problem is that I don't want to ruin tires that are not replaceable.  Also, we have put a lot of work into lacing those rims.
Title: Re: Treadmill Dyno
Post by: REdiculous on April 16, 2011, 11:33:11 PM
20x1.75..standard size. I kind of expected you to be using 20x1.5 for some reason.
Title: Re: Treadmill Dyno
Post by: SparWeb on April 17, 2011, 12:36:16 AM
About spoked wheels:

http://www.amazon.com/Bicycle-Wheel-3rd-Jobst-Brandt/dp/0960723668

Just an idea.  It's a great book from the engineering perspective.  May be some tips about spoke arrangement you'll find useful, but not much about tires, though.

I can't tell you much about the tires either.  My understanding is that you put in the work necessary with those tires, because tubes are NOT an alternative.   I had a few old acquaintances raced bikes in provincial finals, and could have answered your question in detail.  Long ago....
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 17, 2011, 12:13:15 PM
Quote
20x1.75..standard size. I kind of expected you to be using 20x1.5 for some reason.

Wider tires have less rolling resistance.  Air drag is not a concern because we have wheel fairings.

(http://i56.tinypic.com/k15gme.jpg)

These tires are amazing.  Radial construction (only ones you get get), no tread, and good for 102 psi.


Title: Re: Treadmill Dyno
Post by: REdiculous on April 17, 2011, 02:16:39 PM
Who told you wider tires have less rolling resistance? I'm pretty sure the opposite is true which is why skinny 10-speed tires rule for racing.

I didn't feel like there was a big difference between 1.75 and 1.5 but the 1 3/8 tires seem to roll forever in comparison. My 1 3/8 tires are about as wide as 2 pencils side by side - comparable to 10-speed tires. The 1.5 tire is about twice as wide, or about 4 pencils side by side.

102psi, wow! That's double what my tires can take and they're rock hard at that point. 8)
Title: Re: Treadmill Dyno
Post by: Madscientist267 on April 17, 2011, 03:42:39 PM
Quote
pretty sure the opposite is true

Tending to agree here, at least in the logic department. No real world experience to back it up tho.

Rolling friction goes up with the amount of rubber in contact with the road. That's one reason the tire pressure is so high. To keep them from developing the 'flat' spot which would put 'out-of-ratio' rubber scrubbing the road as the tire rolls.

I'd think you'd want to get as close to a laser-cut razor edge as you could possibly get if you want to keep the friction as low as possible.

Sure, at some point it becomes impractical to go too 'sharp'.

Maybe the weight load on the tire comes into play, and PSI (in terms of rubber to road) gets off balance.

... trying to think of a reason to go wider ...  ???

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 17, 2011, 05:02:53 PM
Quote
Who told you wider tires have less rolling resistance? I'm pretty sure the opposite is true which is why skinny 10-speed tires rule for racing.

Several sources, including Schwable and my supermileage book (the team that got 15,000 mpg equivalent).  At the same pressure, narrow tires are worse because they squish more, which is they absorb more energy.  This is also why people say that larger diameter tires provide less resistance, but my book says this is only true because the ground is too soft (polished concrete is fairly hard).  But narrow tires can be pumped up more.  If you have too high of a pressure, the tire will actually get too bouncy, which can cause a significant amount of rolling friction.

http://www.schwalbetires.com/tech_info/rolling_resistance (http://www.schwalbetires.com/tech_info/rolling_resistance)

Most importantly though, how the tire is constructed changes the resistance.  The tire in my picture is the only "radial" bicycle tire made that we know of.  All other tires for bikes are "cross ply".

We have run narrow tires before at 140 psi, but that's because the wheels stuck outside of the car body.

(http://i53.tinypic.com/m9nebk.jpg)

Here are the paper thin tires:

(http://i56.tinypic.com/20f7155.jpg)

The tubing on the rear end is 1" square and the sprocket is #35 chain @ 134 teeth  for reference.  The tire is a 1.75" wide tire.  Side wall thickness is about equivalent to about 3 sheets of cheap notebook paper.  The rubber part is less than 1/16" thick.
Title: Re: Treadmill Dyno
Post by: REdiculous on April 17, 2011, 08:23:25 PM
I kinda get the point they're making but I'm not really sold. It seems like they're saying, "at the same pressure that just so happens to favor a wider tire"...

Look at the pics they show on the right at the bottom. I've never seen a tire that flat, except for when it was actually flat and unridable. ???

edit..incidentally, I checked my 1.5 tire and it's rated for 125psi (I've been running it at 35psi). My 1 3/8 tires are rated for 45psi.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 23, 2011, 05:18:27 PM
Yesterday was a success in general.  We ended up converting an engine to run on points and a coil, which turned out very good.  It looks like the engine that we will use in the final car.  We will probably transplant the flywheel and coil stuff to our brand new engine with the new head.  The we will port and polish it and do a final dyno run.

The coil set up used a lot of power.  While running, it was pulling 80 watts, , which made the coil really hot.  We had to install a switch so it wouldn't drain our battery pack so fast.

While running the treadmill dyno yesterday, the key that holds the 3" pulley on the treadmill motor came out.  Unfortunately, some of the material stayed inside and jammed the pulley on the shaft.  After about an hour of trying various things (hammer, pipes, hair dryer, C- clamps), we gave up and decided to keep running the dyno.  After a few more minutes, we sprayed some lithium greese inside of it.  Once we got it up to about 4k rpm, she decided to let go and fly off the end of the shaft.  The belt didn't fly too far, but the pulley spun on the table for about 20 seconds ;D  It took about 40 seconds for the treadmill motor to stop, since it had no load at the time.

When we got it all back together, we did a couple more efficiency runs using the brand new engine, which yielded 10.1 % compared to the 9.7% for the points engine.  Both percentages were lower, probably caused by the bent pulley.

Also, we got the solenoid clutch working.  Only about 10 min more work is needed for it to be done.  It does take two 14v packs to run it, but as long as it is reliable.

I also did a careful discharge of our lipo batteries to see if they could hold 14v while under load.  It turns out that the computer actually needs >14 volts to run, but putting 26v to it would cause too much heat in the voltage converter.  I ran the 1350 mah 4s lipo pack at 4 amps.  It finally dipped below 14v after 1183 mah, so I deemed it a success.  The computer will pull less than 1 amp.

The carbon fiber for the cooled seat fan was finished and the cupholder was also worked on.

Sorry for the lack of photos.  My camera was accidentally left on and the battery was dead.  Next week, the car should be back from the paint shop and we will put everything in it --> lots of photos then.


EDIT:

I looked at the data from yesterday's dyno runs and calculated the efficiency.

Once I added the # of lightbulbs in, the numbers came out as follows:

The points engine was 10.0% efficient at 1.4 hp.  Peak power was a new record of 2.36 hp.

The brand new engine was 11.3 % efficient at 1.54 hp.

Both efficiency runs were done with the same mangled pulley, hence the lower numbers when compared to before.  The belt was jumping a quite a bit due to the pulley.


I think next week we should add the coil and points to the new engine and possibly port + pollish the intake and exhaust.  I think there is a good chance that the new engine has some differences that may increase the efficiency.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 26, 2011, 05:26:06 PM
UPDATES ;D

http://www.youtube.com/watch?v=4abic1dJ1vo (http://www.youtube.com/watch?v=4abic1dJ1vo)

Another video will be up in a 1/2 hour,

EDIT:    http://www.youtube.com/watch?v=by4lR4Tb6Fw

EDIT2:

http://www.youtube.com/watch?v=QiLdhpWrBbM (http://www.youtube.com/watch?v=QiLdhpWrBbM)

(http://i51.tinypic.com/r6zbdw.jpg)


(http://i51.tinypic.com/ieqbuf.jpg)



(http://i52.tinypic.com/2wp5oj4.jpg)
Title: Re: Treadmill Dyno
Post by: Bruce S on April 26, 2011, 06:29:48 PM
That second one sounded like you have something hitting? Nice response to the governor or throtttle.
 
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 26, 2011, 07:00:32 PM
We aren't sure yet what the sound is yet.  It has the ringing sounds from the flywheel, which suggests that it is the gap on our cam lobe (you can't see it in my pictures) hitting the point.
All of this is on the brand new block, which makes the engine sound significantly different. Much smoother and quieter.  Probably due to the better muffler (last one was pretty much a straight pipe).

As for speed, it really accelerates.  Much faster than even the EFI engine.  Probably capable of doing 2k to 5k in under a second (almost as if it has no flywheel).  With no clutch on the shaft, the flywheel almost stops during the revolution around 800 rpm.  Our throttle didn't have a return spring, so sometimes while we weren't holding it, it would shoot off to 5k+, which is pretty scary with a homemade flywheel that is held on with essentially 1/16" thick aluminum...  Definitely need get our bicycle speed selector hooked up for the throttle cable.  Top speed is probably near 6k, but the con-rod will break.  B&S says the redline should be 4k.

This friday we should port and pollish it and throw it into the car (I hope it comes).

Unfortunately, we shorted out the Doc Wattson twice in the last week, and it looks like the second time killed it.  While we were running the engine, a wire broke off the kill switch and touched our metal table  :(





Title: Re: Treadmill Dyno
Post by: Madscientist267 on April 26, 2011, 09:28:27 PM
What's your dwell on the points?

Not sure exactly of the 'antics' (lack of a better word) of a doc wattson, but if thats average current, ~5A seems WAY high. Is the coil warming up?

It made me think of a story my parents told me about a trip from connecticut to florida in an old 6V beetle, where during a stop for fuel, the regulator on the generator stuck shut and fried the genny. My dad ripped a wire off the generator (details escape me) to stop the fire, leaving the system with no starting or charging capabilities.

They ran the remainder of the trip off the battery, parking at the top of hills and such to restart the engine, driving only during daylight (it apparently crapped out mid afternoon), and stopping when it rained so they didn't have to run the wipers.

How does this apply? If the average current for them was as high as what I'm seeing here, the battery would have croaked north of DC.

They never mentioned charging the battery throughout the trip (even after the short sucked some juice out of it).

Your points should be open most of the time, only briefly closing just in time to open again to fire the plug. 5 degrees comes to mind as a general rule, IIRC. The less the better, but too small and the contacts get bouncy and firing becomes irratic.

Definitely explains your excessive battery drain.

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 26, 2011, 09:47:43 PM
Quote
but if thats average current, ~5A seems WAY high. Is the coil warming up?
I would say that is an understatement.  After 5 min of running, the coil was measured at 150F.  Current was 7 amps average.  I can't recall the current draw when using the 4s Lipo instead of the 4s LiFE battery on the coil, but I think I remember the meter reading 140 watts instead of the 80 watts....   When we opened the gap on the points today to about 0.1", it was reading about 62 watts and the engine was running its best.  Obviously, this gap was way too big.

Note:  We have to use the 1350 mah 4s Lipo  (rule says <1400 mah and 12v).

I would guess the point is open closer to 10 degrees.  This may be too long.

Quote
Your points should be open most of the time, only briefly closing just in time to open again to fire the plug.

I see what you are getting at.  Making a lobe that shape would be more difficult.

Since we are only running the engine for a few seconds in the car, this shouldn't be a problem, but things do get toasty on the table.  Quite honestly, the engine will probably overheat before the coil does (limited air cooling).  I am seriously thinking of installing the extra 0.2A 12v box fan in the engine compartment to keep things happier.  The carbon fiber will melt too if things get too hot (the engine plate, the axle mounts,....).  The tire will probably explode too.

Title: Re: Treadmill Dyno
Post by: RP on April 26, 2011, 10:40:52 PM
Many older vehicles used a ballast resistor in series with the ignition coil to limit the current (sometimes it was bypassed during starting).  I wonder if one could help here.  Since it's a relatively low compression engine it probably doesn't need all the energy that coil can produce to jump the gap.

If you want to try this I'd suggest adding 1-2 ohms (10 to 20 watts) in series with the coil with a switch across the resistor.  That way you can make a simple comparison to engine performance with and without the resistor in circuit.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 26, 2011, 10:49:53 PM
That's a good idea.  We bought some 50w 1-ohm resistors which would work well for this.  Only issue would be finding a heat sink for it.  Maybe the engine mount rail.  Would have to be careful to not leave it on for too long.  I'm think we will have to buy another Doc Wattson for sure. 
Title: Re: Treadmill Dyno
Post by: Madscientist267 on April 26, 2011, 10:54:09 PM
Good call on the ballast! I totally forgot about that...

Might even be able to get by with even higher resistance. 4R7?

That would bring things into the 2-3A firing current, and if dwell is set low enough, the average current would be in the mA range instead of whole amps.

Go with as little dwell and as high resistance as possible to obtain reliable spark under all conditions (RPM, load, etc). Your power requirements will drop significantly.

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 28, 2011, 02:10:37 PM
I did another test today with the coil to see how many amps it was pulling with the LiPo battery (~15v under load).  Turns out it was more than 10A, at which point my multimeter wouldn't read any higher.

After running the engine for 2 minutes, the coil was 190 F....  We will definitely have to do something about it.  Based on our engine testing, the LiPo battery should last at least 2 runs.  We have 3 LiPo batteries, so we can swap them out every run.  One of those 3 will have to run the computer and probably the brake light.  Then I will need 1 or 2 LiFe batteries for the cooled seat and the last 2 for the clutch and starter motor....  That make a minimum of 4 separate circuits, 5 to make things happy.  I hope the computer runs on 12v, which then we can have the computer, brake light, the cooled seat, and the starter motor all on one circuit.  If we can get the clutch tuned to the point where we only need 12v, then everything will be perfect.



Title: Re: Treadmill Dyno
Post by: RP on April 28, 2011, 05:08:59 PM
Would it be possible to replace the two clutch solenoids with a pair of electric lock actuator motors from a car at the salvage yard?  At least they don't require any power to hold, only to switch states.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 28, 2011, 05:30:07 PM
We have a servo that will is good for 300 in*lbs, which would also work.  Maybe we could actuate the starter motor and solenoid with the same  potentiometer (it has 3 outlet ports....).  Only thing would be that the starter motor would run while the clutch is engaged... it should work.


We also got an update from the paint shop.  They said they wouldn't be done til Saturday (last day of April like the promised...).  Hopefully we can pick it up then.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 30, 2011, 03:55:21 PM
http://www.youtube.com/watch?v=M54zXwjRp_o (http://www.youtube.com/watch?v=M54zXwjRp_o)

http://www.youtube.com/watch?v=jW8IP-6N5Lg (http://www.youtube.com/watch?v=jW8IP-6N5Lg)

These are the new videos with ported and pollinated intakes and exhaust.  Just from revving them on the table, the performance is much better, especially in the top end.  We must of hit 5-6 k at less than 1/2 throttle.

The intake originally had the cross sectional area a little bigger than a sharpie marker.  Now it is around 3/4" in diameter.

We also found out that our brand new engine was pretty much destroyed, caused by a lack of oil.  We are not sure how long we ran it for with no oil, but it wasn't very long.  After tearing it apart, we would some real nasty grooves in the cylinder wall and on all of the bearing surfaces.  The engine in my two videos probably has parts from 4 other engines at this point.


Last night, we also swiss cheesed all of the components on the rear axle, probably cutting 1/4 - 1/2 pound.  Also, the wheel covers were clear coated and the cooled seat fan was glued to the air duct.

Today, we are making a new axle for the starter motor.  Having a 4-axis mill makes flat spots a breeze ;D  I should have a video up shortly on that.
I have also been hard at work finding software to make g-code out of a 3D file.  Obviously the companies who sell this type of software are very strict about free software...


EDIT:  Milling some flat spots

http://www.youtube.com/watch?v=yyepHG6iGyE
Title: Re: Treadmill Dyno
Post by: zap on April 30, 2011, 05:11:29 PM
The first video... that engine seems to be smooth as silk!

"Rumble with 14 Robots!" ;D
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 30, 2011, 05:15:00 PM
Quote
Insert Quote
The first video... that engine seems to smooth as silk!

"Rumble with 14 Robots!" Grin

Yeah, 14 robots was a new record, the old was 8 I believe.  None of the robots were mine.

As for the smoothness, yes it was very nice.  The videos don't give the rpm levels justice.  Much more impressive in person.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 02, 2011, 08:57:23 PM
Was able to do 2 efficiency tests with the new ported and polished engine + points.  Came out to 9.4% at full throttle and 3800 rpm @ 2.36 hp (new record!).  At 2/3 hp, we got 8.7% at 2800 rpm.  Not sure yet why the numbers are so low.  I'm going to triple check my excel calculator, but I feel that it is the engine.

If things work out, my brother and I will spend the afternoon messing with the timing and different power levels.

The only variable at this point that has held constant with the lower efficiencies is the extra light flywheel.  I really don't want to give that up, but there is a good chance that this is a significant factor.  Adding mass to the flywheel will be difficult at best.

In a few minutes, I will run the mpg numbers vs. flywheel mass to see if it is worth it to have a lower engine efficiency.

EDIT:  After running looking at the graph, the difference in mpg between the two flywheels is 10 - 15%.  This is not quite as much as the current 20-30% less efficiency than the stock engine.
Title: Re: Treadmill Dyno with a graph
Post by: taylorp035 on May 03, 2011, 09:58:18 PM
Spent a good 6 hours with the dyno today.  Good news, we figured a good many things out that we didn't know, like the timing which resulted in some big gains.

The original image here :  http://i54.tinypic.com/vdguog.png (http://i54.tinypic.com/vdguog.png)
(http://i54.tinypic.com/2e52wye.png)

The blue is the stock engine and the red is from earlier this week.  The green is from later this afternoon after we replaced the curvy small diameter intake pipe with a larger straight one.  The difference is obvious.  Some adjustment in the timing also was done, but it should of stayed constant throughout the green data points.

Some more data for the green in the lower RPM range is needed.

As usual, we were fighting to keep everything from getting too hot.  By running only 10 cc of gas per run, we were able to keep the coil temp under 160F and the engine under 280 F most of the time.  Unfortunately, we did run a LiFeP04 pack down to 5v on the coil once.  I hope we didn't damage the cells.  I charged it as soon as I could (less than 30 seconds after the incident).  It help 2270 mah out of 2300 mah, so guess it is ok.



Title: Re: Treadmill Dyno
Post by: Madscientist267 on May 03, 2011, 10:45:23 PM
Gotta get that ballast in there at the very least man...

Alternately, another thought came to mind about this - Have you guys maybe considered CD (capacitive discharge) ignition instead?

Could probably trigger it optically, making tweaking much easier, and it's infinitely (ok maybe that's an exaggeration) more efficient.

Gotta be better than killing batteries in no time flat and cooking coils...  :o

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 03, 2011, 11:06:39 PM
These are the parts that we have right now.  I don't see us getting new parts until next year.  Plus, a new flywheel or maybe a modified cast iron flywheel with a magneto may be an option next year.

One of our teachers today said the same thing today.  He said something about a 20-30 ohm ballast resistor.

In about 5 min, I'm going to get another doc watson and some more anderson powerpole connectors.  I then plan to also have a "Coli ON" light right in front of the driver so we don't burn the thing out.  More than likely, we will add some of our large 50 watt resistors in series to compensate for the 16 volts.  Having spark was never an issue today.

This morning, I was doing some mph vs RPM calculations based on our gearing and I figured we were hitting 4.5k rpm last year at 26 mph going around the track.  No wonder we only got 6xx mpg during those runs.  When the girl driver in our ground did her final run, she drove slower, more like 23-24 mph and got 777 mpg.  My max speed was 32 mph, which meant 5.5k rpm.... the rod should of broke by then.  While testing earlier today, we accidentally hit 164 volts on the treadmill, which is about 5.5k rpm  ;D  Good thing the lights were not hooked up.

We also hit a new max hp today, at 2.49 and held it there for 40 seconds.  The efficiency was 10.2% on that run.




Title: Re: Treadmill Dyno
Post by: Madscientist267 on May 04, 2011, 12:05:58 AM
Yep limiting the current is the simplest way to fix your heat problem ATM.

5.5k RPM shouldn't be a problem for short runs.

I can't say for sure with the newer engines, but in the late 80s, a friend and I repaired lawnmowers as teens; in our infinite 'wisdom', we would hold the throttle plate completely open as a 'blow up now, not after I sell you' test, sometimes for 30 seconds or more. I don't know the actual RPM, never had any way of measuring it, but they were generally set for 3600 RPM by the governor. The pitch of the sound sometimes would be double (~7200) what it was at normal governed speed. Never threw a rod. The engines were known by HP back then, with the CC listed in fine print below. 3.5HP and (i believe?) 152cc. Its been a while.

But I know for sure the only snapped rod I ever saw on one was on a new engine run hard with no oil.

They were tough little engines back then, and from what I can tell, they haven't changed very much at all. The biggest differences I see (without taking a newer one apart) is that the governors are no longer available as the 'air vane', and the EPA apparently got their grubby mits in the mix, because there's no more mixture needle on the carbs anymore either.

I'm not saying it's a good idea necessarily to open them up like that, but every briggs I've ever abused in that manner took it like a timex. ;)

Man, I gotta quit aging myself hahaha

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 08, 2011, 03:25:34 PM
As expected, the paint shop missed the deadline yet another time.  Monday....

We did wire up a 1 ohm resistor in line with the coil.  The coil was about 1.5 ohms, so a 1 ohm resistor would bring the coil voltage down to 9v or so and the total current should drop by 1/3 - 1/2.  We even got some thermal paste and a small block of aluminum to help get rid of the ~35w.
(http://i54.tinypic.com/mt9i5w.jpg)

The dual action clutch actuator was also finished:
http://www.youtube.com/watch?v=YSGXKcXsJDM (http://www.youtube.com/watch?v=YSGXKcXsJDM)


The engine was also tested some more, now with the iso-octane.  Peak power jumped from 2.49hp to 2.92hp.  Treadmill motor was pumping out 118v at ~18 amps ;D  The intake pipe was also cleaned out a little more and the hole where the old fuel injector sat was covered over.  Efficiency was also calculated at about 12.3%, with the peak closer to 3000 rpm.  Some more work on the timing is in store.

Some calculations on the free wheel were also done.  Looks the torque caused by the bicycle clutch was about 0.18 in*lbs, which amounts to 1300 Joules over 9.6 miles, or about 1/3 of a burn, or about 1-2% of our mileage.  Therefore, the added weight of the hydraulic clutch has about the same negative impact on the mileage.

We also found out that the big 134 tooth gear that we are using isn't really 134 teeth.  Turns out it was 100 teeth... which means every calculation for the last 2 years is wrong... and that our highest possible gear ratio will now be a 8.33, which doesn't bode well with a higher rpm from the engine efficiency.

Title: Re: Treadmill Dyno
Post by: zap on May 09, 2011, 11:24:16 AM
We also found out that the big 134 tooth gear that we are using isn't really 134 teeth.  Turns out it was 100 teeth... which means every calculation for the last 2 years is wrong...
DOH!
Title: Re: Treadmill Dyno
Post by: Bruce S on May 09, 2011, 12:10:10 PM
On the bright-side, it was found out now not the day of the race  ;D
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 09, 2011, 07:40:30 PM
I saw the car with the whites of my eyes today.  Looks like they started painting it today....  Said it would be ready tomorrow.  It looks like they did a little body work.  The color at this point will be 100% white.
Title: Re: Treadmill Dyno
Post by: Bruce S on May 10, 2011, 09:46:19 AM
Nothing like coming down to the wire.
Title: Painted Supermileage Car Photos!
Post by: taylorp035 on May 10, 2011, 08:37:48 PM
The day finally came :)   :P 

Here is a walk around the painted car in HD ;D  (sorry for the bad camera work...)
http://www.youtube.com/watch?v=v71qYfvcudw (http://www.youtube.com/watch?v=v71qYfvcudw)

I took 91 pictures.... I chose 4 for you guys.  If there is a particular angle you want to see (I think I got 'em all, minus a shot under the car), just ask.

You can see the tear drop design quite clearly, especially from above.  Not to bad for a first car.

(http://i53.tinypic.com/343ncxc.jpg)

(http://i52.tinypic.com/244co4k.jpg)

(http://i51.tinypic.com/1zqy8sg.jpg)

(http://i56.tinypic.com/1zg7sq8.jpg)



Title: Re: Treadmill Dyno
Post by: electrondady1 on May 11, 2011, 11:12:28 AM
that is a very cool machine.
congratulations to all
Title: Re: Treadmill Dyno
Post by: Madscientist267 on May 11, 2011, 08:42:06 PM
Agreed. ;)

Hopefully the demons in the power plant and drive train will work out in the entire team's favor.

Very nice job. You have all clearly put some serious work into this machine.

If you had to hazard a guess, what kinda price tag you think this thing would carry if one were to eventually be able to purchase one at say, the local "TaylorP035's Custom Super Milage Cars" franchise?  ;D

As I write this, I envision a trip to California from Virginia for less than $20. This of course takes into account the currently astronomical $3.79/gallon down at the local 7-11, and allows the car to make well under 1000 MPG. The figure that came to mind was the "777", 3x my lucky number. ;)

Anybody ever considered it as an extracurricular activity once the official race is over? I would bet that the mountains would pose a significant problem, but a little bit of hybrid thinking might help with that... I know I would pay to see it! Or even help with that part of the design... ;)

Steve
Title: Re: Treadmill Dyno
Post by: SparWeb on May 11, 2011, 11:37:27 PM
She's real perrrrrty.  (http://www3.telus.net/faheydumas/gifs/thumbsup2.gif)
Title: Re: Treadmill Dyno
Post by: zap on May 12, 2011, 07:51:21 PM
I love the overhead shot.

When are you going to apply the golf ball dimples? ;)
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 12, 2011, 08:54:38 PM
Quote
If you had to hazard a guess, what kinda price tag you think this thing would carry if one were to eventually be able to purchase one at say, the local "TaylorP035's Custom Super Milage Cars" franchise

Well, if put it into production of one every two weeks and a decent profit, then maybe $5,000 - ish.  $1500 C.F., $1000-$1500 for the parts, $2000 for labor...

Quote
When are you going to apply the golf ball dimples? Wink
8)


Quote
As I write this, I envision a trip to California from Virginia for less than $20.

With a few sets of tires and a gear ratio of ~4:1 good for 60 mph (which many of these vehicles have done before..... I even have a photo of one doing 55mph).  I'm not sure how the comfort level would be after 6 days.
This car got 3100 mpg  :o
(http://i56.tinypic.com/dn0ilt.jpg)

Top speed with our 100 tooth big gear and our largest sprocket on the clutch should be ~48 mph.  Probably closer to 75 mph with smaller ring gears.  It would be awfully dangerous on the narrow 3 wheel setup.
Quote
I love the overhead shot.
I was kinda curious myself to see what the shape was.  The interesting part is that none of the cross sections actually look like a teardrop, just the over head view.  With no wheels or tail cone, the drag coefficient was a low 0.079.  It is currently calculated/estimated at 0.103, rounded up to 0.11.


It is also interesting to know that there is no center line in this car.  Definitely not symmetrical, not within 2" ;D
Title: Supermileage Car Driving
Post by: taylorp035 on May 15, 2011, 04:00:31 PM
Here are the videos in order of progress.


Engine running for the first time in the car with friction clutch:
http://www.youtube.com/watch?v=JFriwF1af4k (http://www.youtube.com/watch?v=JFriwF1af4k)

Up close with the servo clutch
http://www.youtube.com/watch?v=w_pifNUDjbo (http://www.youtube.com/watch?v=w_pifNUDjbo)

Running engine with the servo working:
http://www.youtube.com/watch?v=XmMcVWxjgHc (http://www.youtube.com/watch?v=XmMcVWxjgHc)

Driving part 1:
http://www.youtube.com/watch?v=UebHghrXXIE (http://www.youtube.com/watch?v=UebHghrXXIE)

Driving part 2:
http://www.youtube.com/watch?v=J2jNBTJuIVo (http://www.youtube.com/watch?v=J2jNBTJuIVo)


Here is a photo with the logo on it  :)
(http://i56.tinypic.com/zjjsip.jpg)


We worked on the car from 2 pm on Friday til 3 am on Saturday. Then we came back did it again from 3 pm til 2 am.  In that time frame, we installed all of the windows (about 8 man hours), installed the engine plate, the engine, the electronic ignition, the cooled seat (not working very well right now), and the steering and wheel stops.

Title: Re: Treadmill Dyno
Post by: Madscientist267 on May 17, 2011, 06:38:49 PM
"CLUTCH BEFORE ENGINE!!!"  ;D

Hahaha there's learning to build a machine, and then there's learning to operate a machine... LOL

Then again, I guess 'RTFM' was not an option here...  :P

Very nice either way.

Maybe some kind of interlock... To keep the clutch from being engaged if the engine is already running... At least until the drivers have all had a chance to "RTFM"... ;)

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 17, 2011, 09:30:33 PM
One issue was that we didn't have control of the throttle.  We still needed a crimp on the cable to connect to the valve, hence we opted to turn the idle way up (idle is good for 1.4 hp  ;D).

I'm surprised still that we didn't shear off any of those teeth on the clutch... only 2  8-32 bolts holding each tooth on.  And only one tooth actually provides the torque (the teeth are about 175 degrees apart).


Today I went back to the school and took some photos of the other side of the car that has more logos.  I also weighed the car, and it came in at 116.4 lbs, which is about 15 lbs heavier than I wanted.  Only the cooled seat, batteries, switches, computer, and seat belt remain to be added.  I predict a final weights of 123-125 lbs.

Making an 80 lb car is going to be tough next year.... ~ 20lbs less carbon fiber and glue, 10 lbs less Bondo, lighter starter motor, smaller batteries, lighter seat and no cooled seat, lighter computer(it weighs a few pounds), thinner windows, milled engine, maybe carbon fiber rims and steering handle, carbon fiber steering, aluminum bolts (with shear calculations), titanium axles (the old car had these), and a lighter big sprocket (hopefully I can get my workplace to wire EDM me a custom one for a Gates carbon fiber timing belt).

I believe the PAC CAR II only weighed 59 lbs...  Within our rules, we would be lucky to hit 70lbs with a million bucks... they probably spent more.

I sure hope someone can come up with carbon fiber based radial tires ::)  Maybe rate for 300 psi... they make air tanks out of it for 10,000 psi.




Title: Re: Treadmill Dyno
Post by: taylorp035 on May 22, 2011, 03:33:43 PM
The cooled seat cooling mechanism.
http://youtu.be/az0e2GBqiwA (http://youtu.be/az0e2GBqiwA)
(http://i55.tinypic.com/j61ydt.jpg)

We ended up bending and twisting the rear axle last week (not surprised after "dropping" the clutch at 4k rpm).  After some serious calculations, we decided to use last year's axle, which is ~5" shorter and hardened steel.
(http://i52.tinypic.com/jimeld.jpg)

Gluing some mounting blocks in for the shorter axle.
(http://i53.tinypic.com/ei9wyc.jpg)

Front with no wiring.  Took about 6-8 hours to wiring every thing inside of the car.  Used about 30 sets of Anderson Powerpole connectors.
(http://i55.tinypic.com/fk07ck.jpg)

Lightest weight chain guard ever!
(http://i53.tinypic.com/2cpdhfc.jpg)



The kill switches were tricky, because I had to wire up the lights too, so we could identify which switch was flipped. 

Testing in a half lit parking lot turned out pretty good.  Managed to miss the man-hole covers.  Top speed was recorded at 22 mph, but I probably didn't hit 3k rpm.  It was kinda rough to drive since the top of the engine was resting up against the firewall and we didn't have the cushion in at the time.  The steering was very good and easy to keep straight.  The brakes worked well to, as well as our very bright brake light.  It was interesting that the campus police didn't check us out.

The electrical system on the engine worked great.  The battery still had 25% left after running for ~ 10 minutes.  We will need about 2 minutes of run time at the track.  I still need to add a fuse to the circuit.
Title: Re: Treadmill Dyno
Post by: REdiculous on May 23, 2011, 01:44:54 PM
It may be light but the chain guard is kinda redundant since the chain can't grab hold of a pant leg...the back of the seat should be plenty of protection in case the chain breaks.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 23, 2011, 10:13:58 PM
Actually, the chain guard is to protect the fuel line and bottle if it breaks.  Drivers generally have a difficult time exiting these vehicles (all of them are relatively air tight), and most are made of composites that will melt.  Plus, the drive may not be aware of a fire if the chain doesn't alarm them first.

The most dangerous thing though is probably a engine throwing a rod or a flywheel exploding.  0.032" aluminum is not going to stop either situation.  Ultra high compression test engines built by students may not preform as expected :-\.

Title: Re: Treadmill Dyno
Post by: REdiculous on May 24, 2011, 12:57:42 PM
The chances of breaking a chain should be near-nil (especially once you're rolling) and the wheel-side chain shouldn't be moving fast enough to do any damage if it does break. Much more likely is throwing the chain and having it get tangled in the wheel, which the chain-guard won't help with.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 24, 2011, 09:36:58 PM
True... In high school in my battlebots, we had a #35 chain on 4 hp doing 30,000 RPM (not a typo) on a 11 tooth sprocket ;D.

Tonight I balanced the rear wheel and made some observations on how much friction there is.  At the fastest speed that I can spin the wheel by hand, it took 14 seconds to spin down, which is atrocious.  There is probably 0.5 in*lbs of torque in the seals, which comes to 5-10% of our mpg....  The seals will come out after we are done testing in the parking lot.

Sorry about the lack of driving video.  The camera did a poor job since it was so dark.  This time we will open the throttle all of the way.  Initially, we didn't want to break anything on the first major test run and the fact that is was so dark that we probably couldn't of seen any problems that would have developed.
Title: Re: Treadmill Dyno
Post by: JW on May 24, 2011, 09:42:21 PM
It's nice to see remotly hosted images display aswell as pictures attached to the forum. As an Admin, I work hard to make things like that, equal.

JW
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 24, 2011, 10:00:11 PM
It SOOOO easy.    www.tinypic.com   is where it's at.  Just select the photo, type in the scrambled code, and select the size (640x480).  When it's done, copy the "message board" code and paste in the reply.  It's kinda slow for people who have big pictures and slow internet, but it's worth it.

I gave up on uploading photos to otherpower.com b/c it didn't work half the time and I would have to manually re-size them in MSPaint.  As far as I know, all of the tinypic  pictures still work.

If I am really ambitious, I like to provide a link to a higher resolution photo for those who want more detail.
Title: Re: Treadmill Dyno
Post by: JW on May 24, 2011, 10:20:56 PM
Quote
I gave up on uploading photos to otherpower.com b/c it didn't work half the time and I would have to manually re-size them in MSPaint.

Yes thats true, I use MS Image Composer to resize and "save for the web". If you have a picture with over 150k you may have upload problems.

Did'nt I crop and save your Avatar to the OP/Board here?

JW
Title: Re: Treadmill Dyno
Post by: Madscientist267 on May 25, 2011, 01:55:03 PM
For the Linux crowd, GIMP is good for resizing too.

Just open the pic(s), select 'Image -> Scale' and punch 640 in the X field, whack Tab, the Y field should automatically adjust (they are aspect-linked by default) and click Ok.

Save it, keep the default quality setting, and voila, you have your resized picture(s).

99.9% of the time, this pacifies the board's requirements for file size. Every once in a blue moon, I get one that is a little over (usually if there is a crap ton of detailed intricacy in the picture). In that case, I go back, re-save it with 5% lower quality, and it usually snaps right into place.

FWIW

Then again, those running Linux are probably already aware of all of this.

GIMP is however also available for Windoze.

... we now return you to your regularly scheduled thread ...

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 25, 2011, 09:17:44 PM
Quote
Did'nt I crop and save your Avatar to the OP/Board here?

You did.  I showed you guys the photos of me on Presque Isle, and at the same time, I was trying to get an avatar image.  I failed, but one of the admins (JW?) was really anxious to make it work.  He did all of the leg work.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 29, 2011, 07:32:19 PM
Time for a video in the daylight  :)

http://youtu.be/fRXB8IkRB8o (http://youtu.be/fRXB8IkRB8o)

Here is our first actual fuel economy run in the Erie parking lot at Penn State Behrend.  The result was ~400 mpg, which isn't bad when considering that the air drag is ~3x higher than it should be, and we are taking tight turns, which doubles or triples the rolling drag.  Also, the tires are only at ~75 psi, which will go up to 100 later.  Also the ground had a lot of tiny rocks and the bearings still had their seals in them.  Our goal is 1500 mpg.

Average speed was 12-13 mph in this test.  A total of ~8 miles was driven and 1.8 ounces of fuel was used.

Earlier, the driver decided to increase the throttle from rest and this is what happened....

(http://i55.tinypic.com/i5mxlf.jpg)

A nice 25 foot burnout ;D ;D ;D   This is why you put the cheap tires on the drive wheel.  The still looks good, but it demonstrates how thick the rubber is on the "low rolling resistance tires".  If we had our real low rolling resistance tires on there, it would of popped in 10 feet.

There was about 80 lbs of weight on the rear tire... pretty impressive for a 3 hp engine.

The lighter flywheel is very noticeable when compared to last year's car.

EDIT:  2nd video

http://youtu.be/pF-zJwCouxs
Title: Re: Treadmill Dyno
Post by: Madscientist267 on May 29, 2011, 09:23:49 PM
Dang dood... that thing shizn'gits!

Very nice...!

Anybody track any G force measurements during the burn?

I know SOMEBODY has a Droid around there... haha

Steve
Title: Re: Treadmill Dyno
Post by: ghurd on May 29, 2011, 10:01:04 PM
The burnout looks like a classic case of bunny-hopping.
Get some ladder bars on it!
G-
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 30, 2011, 12:27:57 AM
I almost think that the unevenness in rubber is caused by the single cylinder. After twisting our axle, it was evident that the torque was at least 8-10x the rated torque (4 cycle, peaky explosion for that 1 cycle)...

Two kids coming to competition will have a Droid and an I-phone  8 :)

I soooooo wish I had the camera when it was doing the burnout.  It was really awesome.  3.5k rpm easy the whole way.   

So much for going with a supercharged + 18:1 compression + OHV = 6+ hp next year  :P
Title: Re: Treadmill Dyno
Post by: zap on May 30, 2011, 09:49:36 AM
Too cool!

I'm working to get the Silverado above a 21mpg average :-[
Title: Re: Treadmill Dyno - PSB photos
Post by: taylorp035 on May 30, 2011, 10:01:27 PM
I finally figured out how to get you guys the photos that I have on our internal website   ;D ;D ;D ;D ;D ;D ;D ;D


http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures (http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures)

Title: Re: Treadmill Dyno
Post by: zap on May 31, 2011, 10:26:12 AM
Nice pictures... that locomotive cab would look good in my backyard!

What was the "checkered" blue and white seat covering in the '09-'10 build?
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 31, 2011, 06:29:39 PM
It was a custom seat cushion that my mom made last year.  The fabric had a bunch of Penn State logos on it.  She made a new one this year (should be in the pics) that specially contours the crazy frame rails.  We also got it professionally embroidered.

Title: Re: Treadmill Dyno
Post by: zap on May 31, 2011, 08:55:21 PM
It was a custom seat cushion that my mom made last year.

Ahhh... Mothers... where would we be without them :)
Title: Re: Treadmill Dyno
Post by: REdiculous on June 02, 2011, 01:02:14 AM
Moms that sew are cool....mine owns a quilt/fabric shop so everyone in the family has a nice quilt. 8)
Title: Re: Treadmill Dyno
Post by: Bruce S on June 02, 2011, 09:17:57 AM
Moms that sew are cool....mine owns a quilt/fabric shop so everyone in the family has a nice quilt. 8)
OKAY that might be a problem, where are you located?
 I may need to make sure my wife doesn't know, we have more fabric from her old seamstress days than I can store in one closet  ;)
Strange as it may be, quilts fell cooler than other blankets even during the summer, and there's no beating them for comfort.
AHhhhh
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 02, 2011, 08:13:15 PM
Yeah, she does quilts too, handmade, not with a machine.  She is located in NW PA.  She does here magic by working on altering bridal gowns (and the brides that come with them).

Hopefully we use the cushion this year.  Those of us who want every last MPG are willing to fore go the comfort for 40 minutes.  We weighed the car with everything in it (cushion, cooled seat..) and it came out to 127 lbs.  Without the fancy stuff, it goes down to 115 lbs.  12 lbs could mean up to 50 mpg.....

Title: Re: Treadmill Dyno
Post by: REdiculous on June 02, 2011, 09:35:36 PM
Quote
OKAY that might be a problem, where are you located?

We're in Oregon so probably nowhere near you. She has a site (http://www.thefabricfarm.biz/) though, complete w/ an email newsletter. ;D

Quote
Yeah, she does quilts too, handmade, not with a machine.

My mom uses machines but she kinda has to since she does so many. She not only quilts her own stuff but other people's as well and rents out the quilt machine from time to time. And she teaches several sewing classes and has her own line of yarn.

taylor, have you tried getting your mom to drive the car? You should totally try to get her in it for at least a lap.
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 05, 2011, 09:07:22 PM
She will not fit, even though she is not a big person.  The frame rails are only 13" wide where your hips sit... kinda a design flaw.
Title: Re: Treadmill Dyno
Post by: Bruce S on June 06, 2011, 08:55:47 AM
Quote
OKAY that might be a problem, where are you located?

We're in Oregon so probably nowhere near you. She has a site (http://www.thefabricfarm.biz/) though, complete w/ an email newsletter. ;D

Quote
Yeah, she does quilts too, handmade, not with a machine.

My mom uses machines but she kinda has to since she does so many. She not only quilts her own stuff but other people's as well and rents out the quilt machine from time to time. And she teaches several sewing classes and has her own line of yarn.

taylor, have you tried getting your mom to drive the car? You should totally try to get her in it for at least a lap.
I took a look at the website, then told wife about it while handing her a glass of wine  ;D.
It has a nice layout.  There's nothing wrong with using those machines. They do make pretty paterns and if she's as busy as you say, can surely help her a lot.
Cheers
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 06, 2011, 08:19:49 PM
This is the big week!!!  :) ;) :D ;D :o 8)

Testing with the body on it:
http://youtu.be/yz-zbT6U-9M (http://youtu.be/yz-zbT6U-9M)

Here we got 674 mpg in the parking lot.  A lot of the energy was wasted in the corners (tire drag goes up by 2-3+ times for a 20-40 meter radius).  At 23 mph, the front end was sliding.  :o  I was either turn hard or hit a whole row of orange cones.

Top speed was confirmed to be at least 31.5 mph, which translates to 4800 rpm.  Sure sounded good, but there was some really bad wheel shimmy, just like a bad shopping cart wheel.  We also had the rear tire lock up on us.  It was very sudden and caused the tires to squeal and the back end to whip out 90 degrees (sliding sideways in a 3 wheeled vehicle is never a good idea...).  The cause was dirt getting into our wheel bearings, after us taking the seals out 15 miles earlier.  About 3/16" of rubber was taken off a patch on our testing tire when this happened.

After all of the testing in the parking lot, the front frame holding the steering gave out.  Several cracks in the welds occurred, which caused the car to have only 1/4" of ground clearance and 15 degrees of toe -in.  Needless to say, we took 90% of the tread off our priceless radial tires in the process.

While looking at the university of Laval's website, they got 2909 mpg in Europe last week....  and took 13th.  First came in at over 8000 mpg set by a car named "Microjoule".

Thank goodness for extended wheel based mini vans :)
(http://i53.tinypic.com/161hoxv.jpg)

EDIT:

I was thinking of a new driving strategy.  Currently, we turn the coil on and then fire the starter motor.  Since she fires on the first revolution, the starter only gets to about 500-900 rpm.  Option two, which we haven't tried yet, is to turn over the starter at full speed (1000 rpm), and then turn on the coil.  According to our instructor, he doesn't think the engine sucks fuel until it fires.  We could swap in the lipo battery and boost it up to 1300 rpm and loose 0.4 lbs.  Together, my calculator says we gain ~40 mpg over our current set up.  I wonder though, which method is better?

 
Title: Re: Treadmill Dyno
Post by: Bruce S on June 06, 2011, 10:53:45 PM
What No windshield wiper  ::)
Looking good. The line looks like a cute Cheshire cat style grin  ;D
Thinking of the shimmy, is it possible there not enough camber in the front wheels? allowing the dirt to enter the bearing area?
it's always the little things.
My opinion would be to get the coil over firing RPM then shut down the starter.
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 06, 2011, 11:03:22 PM
We could run the starter for the entire burn.  The starter pinion has no spring on it, so only acceleration will cause it to go into the flywheel.  Could be violent though if it catches the flywheel at 4k rpm... have seen this many times on the dyno.  Usually small pieces of plastic will shatter off the pinion gear.
Title: Re: Treadmill Dyno
Post by: Madscientist267 on June 07, 2011, 12:38:45 AM
Eek. I wouldn't. But I'll get to that in a second...

The two possible means of fuel delivery are:

1 - If the engine is carburetted, the engine will suck fuel in whenever the intake valve is open and the piston is going down.

2 - If the engine is fuel injected, the engine will 'use' fuel whenever the injector is open. I VERY seriously doubt that an EFI system for a small engine such as this would be 'aware' of whether or not the injector should be enabled or disabled automatically. To my knowledge, it doesn't even happen on yer fancy(er) four bangers.,,  If the 'ignition' is on, so is the fuel injection system, and the injector will fire fuel based solely on crank position.

All that being said, neither requires the engine to actually be firing to 'use' fuel. #1 does it due to natural aspiration pulling fuel into the venturi. #2 does it because the fuel is under pressure, and the valve that lets it out is open. Either way, you're dumping fuel into the engine, and if it's not providing the 'bang' part of 'suck-squeeze-bang-blow', the fuel is going out the tailpipe, lowering your MPG.

And the starter thing is kinda unrelated to the MPG thing, although would SERIOUSLY increase it if this should happen. But something tells me you'd be disqualified for cheating (I'm going to assume that 'pushing' is not a valid form of power input  ::)). You really want to risk losing your starter in the middle of the race because you shaved the pinion clean? :(

If you're fuel injected (and I think last count was that you were), you'd be better off having the coil firing whenever the engine is physically turning, 'running' or not, then modulate the fuel as the very last thing. Saving fuel IS the idea here, right? Or did I miss something...  :D

Disabling the injector may or may not be a trivial task, but I'd view it as an important consideration in saving fuel.

My 10-steps-to-win proposal:

1 - Crank the starter up to full speed (as you proposed)

2* - Don't forget - CLUTCH BEFORE ENGINE!!!  ;D

3* - Enable coil

4* - Enable the injector

5 - Shut down the starter once the engine fires.

6 - Run the calculated burn.

7* - Kill injector.

8* - Kill coil.

9* - Release clutch

10 - Rinse and repeat as conditions require to win the race!

* - You can probably combine 2, 3, and 4, as well as 7, 8 and 9 into just two discrete steps, by careful selection of a switch (and maybe relays) to do the work for you, leaving only a 6 step process. ;)

Since you're not charging your cranking/ignition batteries by any means (from the car's engine), there's no MPG penalty whatsoever to letting the waste take place there. Provided you have enough capacity to provide cranking and ignition for your needs throughout the race, you'll be all set.

If you're not comfortable with the amount of time left to try and coordinate such a design, pray the drivers can memorize everything! LOL

Good luck either way - Will be cheering for you guys from here in VA! ;)

Is this thing televised by chance?

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 07, 2011, 09:15:14 AM
Quote
Is this thing televised by chance?

Umm... not really.  It should be and maybe the local stations might have something.  Shell came out last week with a nice 5 part mini series video (15 min total) from the Shell Ecomarathon last week in Europe.  Laval was in the video with 2909 mpg.... I think they have 1st place in the bag at this point.  I watched the whole video last night and I think it was worth it.

Quote
If you're fuel injected (and I think last count was that you were)

Nope, we are back to the coil and carbed engine.  I runs really really good.


As for the firing plan, I think we will stick to our original:

1) Flip kill switch -->  Turns on iginition system and coil
2) Turn servo tester to activate the starter
3) Hold on for dear life
4) In about 2 seconds, estimate your speed and when you hit 20 mph, cut the engine
5) Make sure everything is off (starter, coil)
6) Coast until speed is down to 10-12 mph, depending on race plans and my calculator


If we use our servo operated plate clutch, there will be extra steps and another servo tester.


Spinning up the flywheel isn't necessary illegal, so long as all of the energy that propels the car comes from the fuel.  At 10 mph, we are at about 1500 rpm, which is lower than the starter rpm.  In theory, we could go 24v and boost the starter to 2000 rpm, but that would be cheating and our instructor would let us walk back all the way to Pennsylvania.



Title: Re: Treadmill Dyno
Post by: zap on June 07, 2011, 10:04:06 AM
Sitting in the minivan, the car doesn't appear symmetrical.  Optical illusion or is that one of the "flaws" you mentioned earlier?

The list of Shell video on youtube:
http://www.youtube.com/user/Shell?feature=mhsn&#g/c/027E2B6D9900A88F (http://www.youtube.com/user/Shell?feature=mhsn&#g/c/027E2B6D9900A88F)
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 07, 2011, 07:07:36 PM
You are right.  It is not symmetrical.  There are two center lines about 2" apart.

Title: Re: Treadmill Dyno
Post by: taylorp035 on June 13, 2011, 08:50:16 PM
Sorry for not posting sooner.  I had a giant mega post last weekend and my browser crashed :-\

1011 mpg and 5th place.  18 cars put a number on the board out of 25 that showed up.  32 teams payed the $600 entry fee. 
Title: Re: Treadmill Dyno
Post by: zap on June 13, 2011, 09:19:21 PM
1011 mpg...NICE!

Where did that put your team... how did that mpg rank?
Title: Re: Treadmill Dyno
Post by: Madscientist267 on June 13, 2011, 10:00:13 PM
Pretty good dude.

Congrats!

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 13, 2011, 10:39:18 PM
Our old record was 777 mpg....

1st place was 2158 mpg, 2nd = 1615 mpg, 3rd = 11xx, 4th = 1070 mpg
Title: Re: Treadmill Dyno
Post by: Bruce S on June 15, 2011, 12:24:59 PM
Hey, not bad for all the work put into it, you increased your mileage by nearly 31%.
Do you have any info on how the car and the engine performed?
Thanks for the update
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 15, 2011, 07:56:37 PM
Well, we stuck with the 100:12 gear ratio.

The first run:  All cheap bike tires from schwalbe - smooth with no tread.  They were pumped to 85-90 psi.  Both LiFe batteries for the starter and the carpet for driver comfort + a mostly empty water bottle.  The result = 769 mpg running a 15.5 mph average.  21 to 10 mph.

Second run:  Front two tires got switched to the radial tires.  Pumped to 85 psi.  New driver.  Average speed of 15.1 mph going from 21 to 10 mph.  Result = 1011 mpg.

Third run:  Canceled after 3 laps due to severe weather.  Pumped up the tires to 103 psi, lost the carpet, water bottle, original driver, 19.5 mph to 11 mph.  Driver thought things were going really well.

Fourth run: 2 hours later...  Same as 3rd run.  Just as the driver was starting the last lap, the front right tire popped like a balloon.  The car then dropped down onto its wheel skirt and ground to a stop.  Probably would of had 1200 mpg and 3rd place.  After later inspection, both front wheels had numerous holes in the rubber that extended down to the threads in the tire.

Fifth run:  Replaced both front tires for the super thin blue tires.  Also put in the experimental clutch in the rear that completely disengages the rear wheel from everything.  Once on the track start line, the clutch wouldn't engage. 

Here are the competition photos and the team photo at the end.  We are currently working on building ourselves a custom 180 tooth timing pulley for a carbon fiber belt.  This should boost drive train efficiency by about 3-5% at least and save 2-3 lbs.

http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures (http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures)
Title: Re: Treadmill Dyno
Post by: ghurd on June 15, 2011, 08:28:12 PM
Uh, I am sure it was covered elsewhere, but these are 'bike size' tires right?
I see knuts at the Presque Isle (and other) time trials put 140PSI tubeless tires up to 175.  Or 200.  Carbon rims or not.
Can get that grade of tire for <$30 on sale.
Just thinking out loud,
G-
Title: Re: Treadmill Dyno
Post by: zap on June 16, 2011, 12:15:57 PM
I'm pretty sure they were "bike size"... I think 20"?

And speaking of tires...
Looking at the pictures, I was surprised there seemed to be a number of vehicles with exposed tires and of those, none seemed to have "areo spokes" nor were the spokes covered in any way, such as this entry from  Michigan Tech:
https://d1q9wbuypc40mm.cloudfront.net/lrdys76phdts7c_710.jpg (https://d1q9wbuypc40mm.cloudfront.net/lrdys76phdts7c_710.jpg)
Title: Re: Treadmill Dyno
Post by: ghurd on June 16, 2011, 12:32:36 PM
Some spokes are more modern than expected.
Wife's spokes look like wire from the side, but are actually flattened to be very thin.  Almost like narrow stips of thin sheet metal.

I should not have narrowed it down to tubless earlier.
Oh, and I also sometimes see those over-pressured tires pop.
Not very often, but it happens.
If it happened often they wouldn't do it, because blacktop moving past flesh at 35MPH is painful.
G-
Title: Re: Treadmill Dyno
Post by: DanG on June 16, 2011, 12:50:10 PM
(https://d1q9wbuypc40mm.cloudfront.net/405saa0cgafec8_710.jpg)

Sweet.

Which was 2nd & 3rd?
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 16, 2011, 05:35:07 PM
^DanG -   Those are old photos, at least 2008 or older.  The white car in the middle was the winner for sure (University of British Columbia).  That car got 3100 mpg.

Quote
Uh, I am sure it was covered elsewhere, but these are 'bike size' tires right?

20" tires are really only made for kids bikes and BMX bikes.  If you go to any website that sells high performance bike parts, they usually don't even list the tire diameter, because they are all 700mm ~ 26-27".  There are hunderends of choices in the 26" category, and only about 10 in the 20" section.  Now try to find aerodynamic rims in 20".....  or even light weight aluminum.

To make things harder, spokes for 20" rims that are "bladed" or flat are also very rare.

For tires, there are some recumbent bike tires, but that's it.  This year, there were ZERO supermileage tires manufactured (our blue $75 paper thin tires sold out in February).

Quote
Oh, and I also sometimes see those over-pressured tires pop.
I talked to several Laval students who went to Europe about the tires.  They have the true tubeless radials over there.  Even the top teams sometimes opt not to run them tubeless because one small rock will cause them to leak.  They say that they pump them to 205 psi..... :o   In Michigan, Laval ran tubes even though they have their own custom made carbon fiber tubeless rims.  I would kill for a set of those.  We could of had 2000 mpg with those with our stock engine and heavy car.

Quote
Looking at the pictures, I was surprised there seemed to be a number of vehicles with exposed tires and of those, none seemed to have "areo spokes" nor were the spokes covered in any way, such as this entry from  Michigan Tech:
https://d1q9wbuypc40mm.cloudfront.net/lrdys76phdts7c_710.jpg

Akron had exposed 26" wheels with really nice wheel covers.  Else, everyone else decided not to do anything.  Keeping the wheels inside of the car reduces frontal area and lessens the disturbance caused by outside wheels + the steering knuckles.

Quote
I see knuts at the Presque Isle (and other) time trials put 140PSI tubeless tires up to 175.  Or 200.  Carbon rims or not.
Can get that grade of tire for <$30 on sale.

But their rims aren't 1.75" wide either.  Or $30 tires from Schwalbe were their best 20" tires.  Good for 6 bar (88psi).  If I could get the european Michelin Radial tires, I would be willing to pay $300+ per tire.  Would need 4 tires most likely. 






Title: Re: Treadmill Dyno
Post by: taylorp035 on June 18, 2011, 05:20:17 PM
Here are three videos.  I might get the slalom and brake test videos up if I'm ambitious.  I'm currently working on a new C.F. timing sprocket.  it will be 18" in diameter and be able to support 720lbs of tension  from the belt.  The sprocket should weigh about 1.9-2.3 lbs.

http://youtu.be/K31VZ4Kt0Nc (http://youtu.be/K31VZ4Kt0Nc)

http://youtu.be/VOGaS4O3wXE (http://youtu.be/VOGaS4O3wXE)

http://youtu.be/K31VZ4Kt0Nc (http://youtu.be/K31VZ4Kt0Nc)
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 19, 2011, 04:09:34 PM
http://youtu.be/KRorTecia4w (http://youtu.be/KRorTecia4w)

First car:  The winner at 2158mpg.  Universite de Sherbrooke

Second car: Car from Hawaii.  It got 197 mpg.  You can probably guess that the squeaking as it drives by is not good.

Third car:  First through tech inspection.  I liked to call it the "snowplow".  Probably was 10-11 feet long.  651 mpg.  Not bad for outside wheels and a lumpy body.

You can see that it was quite windy... should of used my windmill to power the lap timer.  The good cars still were going at 10-15 mph when they passed the camera, after coasting ~0.5 miles from the hill.  Of course you had to driver into the wind on the other side :(



And here is the three speed transmission car.  Waaaaay too complicated for my taste and they are probably only 60-70% efficient though the entire transmission.

http://youtu.be/vRKM-40dR2w

During this video, they only used 2 gears, but while our team was driving around the track, they said you could hear them rowing through all three gears on every burn.  Probably hitting 5k rpm on every gear.
Title: Re: Treadmill Dyno
Post by: zap on June 19, 2011, 10:30:09 PM
Second car: Car from Hawaii.  It got 197 mpg.  You can probably guess that the squeaking as it drives by is not good.

Ok... so...
What would your best guess be for mpg if I were to make just some quick and cheap 3 or 4 wheeler and toss your garden variety B&S on it with say... a centrifugal clutch?
Title: Re: Treadmill Dyno
Post by: Madscientist267 on June 19, 2011, 11:26:08 PM
Uhh, aint that called a 'go-kart'? LOL  ;D

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 20, 2011, 06:19:34 PM
Quote
What would your best guess be for mpg if I were to make just some quick and cheap 3 or 4 wheeler and toss your garden variety B&S on it with say... a centrifugal clutch?

Umm... if you had a steel frame, a 10% efficient engine (fairly conservative), 3 or 4 wheels, and a crude body, cheap tires, simple #35 chain...

250-300 lbs + driver weight and a drag coefficient of 0.3-0.5...

Driving an average of 20-30 mph on a paved road....


100-200 mpg if you ran the engine constantly, better of you could use a 50cc OHV honda.

300-400+ mpg if your burned and coasted with a simple bicycle clutch on the rear.


There have been 500 lbs supermileage cars that look like hummers that have gotten 200 mpg.  Rolling resistance is key


If you literally mean a four wheeler (ATV), then the low pressure tires are going to hurt you badly.  The stock engine (a 250cc honda, Yamaha, or equivalent), will probably be better than the B&S.  Just put some small car tires on it or bicycle tires.  Bicycle tires are about 2x better than car tires for rolling resistance.


Title: Re: Treadmill Dyno
Post by: taylorp035 on June 20, 2011, 10:58:11 PM
My next project  :)   180 tooth super custom carbon fiber timing sprocket.

(http://i51.tinypic.com/530ehz.jpg)


I am cutting out the spokes as I type this.  The outside will be much thinner in the aluminum version.  Later this week we will buy the belt, which won't be cheap.  This way we can make sure the tooth profile is correct and nothing will bind up.
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 21, 2011, 08:57:18 PM
Sprocket Loading Conditions

Max tire normal force:  80 lbs
Max coefficient of friction:  0.9 (more like 0.8 )
Tire Diameter:  19.56”
Sprocket diameter:  18”  (really close)

Max torque applied to the wheel = 80 lbs *  0.9 * ( (19.56/2) / 12 ) feet   =  58.68 lb*ft
Equivalent belt tension =   58.68 lb*ft * (12 / (19.56/2)) = 72 lbs.


From the engine side:
From previous engine tests, max average torque is 4.1 ft*lbs
Considering the lightweight flywheel and the total of 4 cycles 
4.1 ft*lbs * 4 cycles * 2x peak during the combustion stroke = 32.8 ft*lbs
Correct for the ratio :  32.8 * 180 / 22 teeth = 268.36 ft*lbs  
Belt tension would then be 329.28 lbs.

EDIT:

And here is a sketch of my new engine design.  I know it is really rough, but maybe you guys will get the idea.

Link to full size:  http://i55.tinypic.com/i7963s.jpg


(http://i55.tinypic.com/10eh9id.jpg)
Title: Re: Treadmill Dyno
Post by: zap on June 23, 2011, 08:56:01 AM
Uhh, aint that called a 'go-kart'? LOL  ;D

Steve

Ahhh... yes... a go-kart :-[

100-200 mpg if you ran the engine constantly, better of you could use a 50cc OHV honda.

Thanks taylor!

I asked because a few years ago I was out on the ebike and I saw an older gentleman climbing aboard a rather large delta trike at WalMart.  It had a 5 hp or so B&S or similar, hooked to a NuVinci drive.  I'm not sure how he did it without getting busted by the cops because IIRC, there were no pedals but the thing wasn't licensed either and he'd ride it on the sidewalks.  The build quality was excellent.

He told me he had ridden it all the way to Greeley which is about a 50 mile drive from where he lived.

He took off and I followed him for a ways till he went west and I went east.  The trike zipped right along.
Title: Re: Treadmill Dyno Tire Testing
Post by: taylorp035 on November 30, 2011, 10:41:51 PM
In the last few weeks, we have been testing our new tires on our rolling resistance testing rig (the design and exact data is a secret for now).

The results:    So called "low rolling resistance" tires are complete garbage when compared to our blue supermileage tires and the radial tires.  We found that the thin construction, wide supermileage tires at 25 psi were still much better than the so called "low rolling resistance" tires at 100+ psi.  One reason for this is because nearly every tire sold has some type of puncture protection, which increases rolling resistance by a very large amount.  At the same pressure, the difference was about 2-2.5x worse/better is rolling resistance.

We found increased pressure affected the rolling resistance of the various tires differently (some linear, some logarithmic).  I found this to be very interesting.

The worst tires we tested were our "snow" tires, which were a set of $9 Michelin Diablo tires.  The thick, sticky tread pattern is the main problem.  These tires were about 6x worse then our best runs with the other tires.

Other things that helped included finding the right tire tubes.  Obvious thick ones are going to be worse, but the question was by how much.  Well, the difference between our two different thickness tubes was about 20%.  Latex tubes would be even better, if you could find them in 20" format. 

The best would be tubeless, which our tires just so happen to be rated to be  ;D   So, this week's hard work has yielded us with a semi-working tubeless set up using our paper thin tires and normal bike rims.  With I little more work, we should have them totally sealed (a few more runs to walmart to the kids bike section will be needed).  The secret construction is still under wraps until we get some data off of it (or you can PM me).

Next up will be trying the radial tires without tubes.  Supposedly a Crr of 0.0008 can be achieved... way lower than about 0.006 for a good bike tire (notice the missing zero).   Inflation pressure will be modified too for this year, hopefully going past 100 psi after a few runs are put on the board.  100 psi is a lot for a tire that is about 3 layers of paper thick :).

For you bicyclists out there, big 700c racing tires for bikes have rolling resistances in the 0.005 range  (data from continental).  The only advantage to the big ones are that they are more aerodynamic... which I doubt it matters much considering the size of the rider going through the air.

Else, we turned a few hundred pounds of copper today for scrap money...    Work on our acceleration dyno should be complete by this weekend.  It's an old senior design project that never ran, so it will be nice to see it running.  It has an air disk brake and a rpm gauge. 


The new car design was mostly completed over the Thanksgiving holiday.  Hopefully construction will start in the next 3 months.... it's going to be a great car, hopefully weighing in at about 10 lbs, which would include the windows and the structural frame.  If it is 15 lbs, I won't be too unhappy, as long as it isn't 41 lbs like our current one.

Classes will be done in 2 weeks  :)

Title: Re: Treadmill Dyno
Post by: SparWeb on December 01, 2011, 12:07:08 AM
Quote
... Supposedly a Crr of 0.0008 can be achieved...
   

No I noticed the extra zeros!!

That's 20x less than your average auto's steel-belted 4-ply.
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 03, 2011, 03:23:20 PM
Here is a video of our new flywheel dyno in action   ;D   Even though the stand and flywheel was already built, it took us a good 20+ man-hours to get the thing running and hooked up to the engine.

http://www.youtube.com/watch?v=IT1sqSlVmss (http://www.youtube.com/watch?v=IT1sqSlVmss)

The rpm's are in the description of the video.  In general, they were between, 333 and 1000 rpm.  At competition, we would shoot for about 333 rpm to 700 rpm. The loud clicking sound is from the brake rotor rubbing.

The flywheel and the correct gear ratio fairly accurately represents the load of the actual car, which should allow us to do some more testing and find out how to make the engine run the best.  Starting the engine below ~400 rpm on the flywheel is a real chore (as you can see), since the starter only goes to about 230 rpm.  Maybe I will kick up the voltage to 26v from the current 16v for next time.

After getting it going, we did 12 burns in a row to simulate half of the race.  After crunching the numbers, the fuel efficiency came out to ~1400 mpg, which seems just right.




Title: Re: Treadmill Dyno
Post by: hydrosun on December 03, 2011, 06:45:59 PM
 Very interesting following this thread. It shows all the compromises made for a reliability and comfort on my bike. I ride a 700cm road bike with Nuvinci gearing, 31cc suburu robin engine,from Statoninc, Zipper fairing, slime tubes and get over 200mpg with me pedalling too. changing a flat tire is hard with the extra chain coming from the engine. So the compromise fo a heavier tire with slime in the back tire. I have a body stocking to further cut wind resistance but riding on the road with traffic was too unerving with car side winds. A tail would help as much as the fairing but would get in the way. Since I'm pedalling too I need air flow on me to keep cool on long rides. So I have to be content with 200 mpg on a slightly modified road bike. I've put in over 5000 miles with this setup. I suppose the engine could be improved but I just put in enough maintainence to keep it running.
Chris
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 03, 2011, 07:34:23 PM
200 mpg sounds pretty good to me for a bike.  The tire for sure is hurting the mpg a lot, especially with heavy, protection guarded tire tubes.  I would suggest using some lightweight tubes as long as you have a big enough tire to avoid pinch flats.  I would also use wider tires.   Wind resistance is fairly high too as you pointed out for a bicyclist, so slower speeds should help.  My supermileage car would would be the happiest if I could average 10 mph most likely instead of 15 or 20 mph.  Maybe some spoke covers would help.

The hard part about projects like yours is that saving another 50 mpg doesn't really justify large investments on parts.  More air in the tires will always help, but once you get much past the recommended max pressure, sharp objects become a problem for flats.  It would be easy to drop $100, $1,000, or even $10,000 on upgrades to your bike  ;D

Title: Re: Treadmill Dyno
Post by: Madscientist267 on December 04, 2011, 08:43:36 PM
Here is a video of our new flywheel dyno in action   ;D   Even though the stand and flywheel was already built, it took us a good 20+ man-hours to get the thing running and hooked up to the engine.

http://www.youtube.com/watch?v=IT1sqSlVmss (http://www.youtube.com/watch?v=IT1sqSlVmss)

The rpm's are in the description of the video.  In general, they were between, 333 and 1000 rpm.  At competition, we would shoot for about 333 rpm to 700 rpm. The loud clicking sound is from the brake rotor rubbing.

The flywheel and the correct gear ratio fairly accurately represents the load of the actual car, which should allow us to do some more testing and find out how to make the engine run the best.  Starting the engine below ~400 rpm on the flywheel is a real chore (as you can see), since the starter only goes to about 230 rpm.  Maybe I will kick up the voltage to 26v from the current 16v for next time.

After getting it going, we did 12 burns in a row to simulate half of the race.  After crunching the numbers, the fuel efficiency came out to ~1400 mpg, which seems just right.

Man that thing bucks like a bronco at the lower RPMs LOL - Guessing that it is this phenomenon added to the close proximity of one's appendage to the wheel with teeth that prompts one to say something like "never been so scared for the sake of my foot in my life" hahaha

Thing of it is, what do you do in the actual car? You don't just crank on the starter until you get it "up to speed" and then apply spark do you? (Assuming that's how you modulated the engine here - took me a couple passes to realize that it wasn't difficulty starting the engine, but difficulty starting the flywheel) LOL

I had a brainy-fart kinda idea while I was watching the vid... I realize something like a slip clutch is not going to cut it in the mileage arena because it would just waste the absorbed energy as heat, but what about something that returns [most of] the energy it absorbs? A heavy axial spring that gives the crankshaft a couple rotations worth of freedom but that can then be locked hard (much like a torque converter lockup in an automatic tranny) once the driver deems it's time? Something along the lines of a recoil spring for a pull start mechanism comes to mind, only both parts are of course rotating, and the version for the car would have much less angular freedom and a much stronger spring...

Just a thought... That way you could get the most out of your engine, I would think. Might require a slightly heavier flywheel to 'carry through' the lower RPM range, but might be worth a shot... ?

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 05, 2011, 10:36:26 AM
Those were some good thoughts Madscientist267.

When the engine is in the car, we have the centrifugal clutch hooked up, which provides the slipping.  It slips very well at 1000 rpm on the crank (starter motor max rpm), but obviously doesn't slip much at 1500 rpm (at our lower starting speed of 10 mph).  Since our clutch is of the fancy adjustable weight type, we could (and will) do some testing to get the best efficiency and make some observations.

Unfortunately, as you saw in the video, the engine currently has no clutch, so the starter has to spin up the freewheel (probably pulling 1000 watts :) ).   If the engine was unloaded, the first fire of the piston would kick the rpm up from the 1,000 rpm to something much higher and everything runs smoothly.  Without the clutch, it's running into a brick wall.... and the engine has to survive at 1,000 rpm.  Not a good thing for a tiny single cylinder engine.


The torsional spring idea could work while the car is moving, but when you start from 0 mph, the starter motor would effectively drive the car = a big no-no.   You could still do it if you had a second clutch, like a centrifugal clutch with a lower rpm on the crank, or a mechanical clutch on the rear axle.  All of these add weight and complexity.  But certainly not out of the question.

Sometime soon, our timing pulley for the centrifugal clutch should be finished and we could then drive the car.  A few other things need to be finished, like our new front steering (95% done), and the rear engine mount (75% done, and a bunch of tape + zip ties to hold all of the components down.


Adventures with the tubeless tires should be continuing also, and we may be able to do some rolling resistance / steering alignment tests in our long hall way.
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 22, 2011, 07:41:25 PM
Today I did some calculations to figure out engine efficiency from the flywheel dyno results.  As I would of guessed, efficiency during acceleration is much lower than at constant speed.  The numbers worked out to about 7-8% efficient, compared to the previous 12-16% efficient from the treadmill motor set up.  More tests need to be done for sure, especially since we were finding air bubbles in the fuel line, mostly likely from the float bowl.  We also found out that there is a high speed idle screw on the carburetor, so we can more easily control our high speed AFR ;D

EDIT:

Our fuel usage from last year for 1011 mpg = 36 cc for 9.6 miles.  This translates to about 15 cc on our flywheel dyno test.  So far, our current engine (over 6 dyno runs) has used 11-16 cc.

Title: Re: Treadmill Dyno
Post by: Madscientist267 on December 24, 2011, 09:50:27 AM
Thats a pretty decent improvement as far as I can tell... Hopefully it translates to the real thing with the same ratio. ;)

Steve
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 12, 2012, 04:27:37 PM
We found out yesterday that the stock compression ratio is 6:1......  = not good.  The new head calls for ~13:1, which we hope to make some chips tomorrow.

We also received some new tires  ;D ;D ;D ;D   We haven't been able to mount them tubelessly, but we don't give up too easily  :)  If our predictions are right, this set up will be the best that we have ever tested in terms of rolling resistance.

Title: Re: Treadmill Dyno
Post by: taylorp035 on January 31, 2012, 06:28:23 PM
UPDATE:

After 2 years of figuring this out, we finally managed to mount our thin supermileage tires tubelessly without leaking any air without building custom spoke-less carbon fiber rims.  Considering our rolling resistance tests and the gains found by making the tubes thinner, we expect the results to be very, very good with out the tubes.  Michelin claimed a 100% - 200% drop in rolling resistance in their best tires by going tubeless.... obviously, there are a lot of factors, including if the tubes are butyl or laytex (finding 20" laytex tubes is very hard) and how thick the tubes are.... there are some discontinued japanese 20" tire tubes that weigh 1/2 the weight of our lightest ones that we currently own, but at $25/each and getting them shipped over here from Japan, it may not be possible or worth it.

We also received our shipment of 6 new supermileage tires... it took significant amounts of effort to obtain these (again, 2 years of trying).  Now only if we could get the radial tires.....  I think there would be a North American mpg record that would be broken.  Our goal this year is to set the SAE USA record, which we believe stands at ~1640 mpg.  Shell ecomarathon participants from California have achieved 2800 mpg...

The other big news is that we started construction of the new supermileage car.  The car body should be about ~30% as heavy as the 2011 car with less than 70% of the frontal area and a lower drag coefficient (significant amount of time was put into CFD software over the last 8 weeks.)  As a bonus, the driver will get more room and the engine bay will be less cramped.  Last week, we had 8 people drawing and cutting foam out for a solid 4 hours and we only got half way done (the car has 61  2" thick cross sections....), each of which required a 3 step process and 2 cross sectional drawings to be applied to each with a Sharpie Magnum  ;D.  As you can tell, we decided to skip the CNC cut mold, due to several practicality issues and the tricky part of getting a company to donate ~$20k-30k of labor and machine time to make it.  Also, it would of dragged the whole process down and been more expensive on our part, due to the extra foam and fiberglass mold supplies.  So, as a part of making everything fit together, we made an 8 foot long giant shish-kabob to prevent torsional misalignment and bending.

The new engine head should be assembled later this week and hopefully be run in two more weeks time.  We expect it to be much more efficient and have way too much power  ;D
Title: Re: Treadmill Dyno - burnout video
Post by: taylorp035 on February 12, 2012, 04:44:38 PM
The new body is moving along at breakneck speed.  If you guys want a picture of it, you can PM me and I will gladly send it to you.

Else, we did some fun testing of the new components in the old car.  The new timing belt worked better than we could of hoped and the ultra light engine mount didn't bend.  Unfortunately, the car had less than 1/8" of ground clearance and the rock salt on the ground gave the car some problems.  Hence we installed our extra large winter tires for the test to increase the ride height a bit.


The tire was spinning pretty much the whole time the engine was on, so the burnout was about 50 feet long.  ~70 lbs of traction and ~40 ft*lbs of torque should break loose any bicycle tire  ;D


Our new OHV engine head should be done on Monday...

Our competitors from last year that took 1st place... they claim $48k in sponsorships.... our new car should do the same mileage for 1/10th the cost.

Title: Re: Treadmill Dyno
Post by: taylorp035 on March 09, 2012, 04:32:39 PM
http://www.youtube.com/watch?v=lp7ca1bBWOM (http://www.youtube.com/watch?v=lp7ca1bBWOM)

Better video of the burnout.

Here are the new rocker arms for the overhead valve engine   ;D   

(http://i42.tinypic.com/2zz5nba.jpg)

A picture of the new head...

(http://i44.tinypic.com/2q9cke9.jpg)

We are still keeping pictures of the new car under wraps.... maybe in a month, you guys will get to see it  ;)
Title: Re: Treadmill Dyno
Post by: Bruce S on March 13, 2012, 02:30:26 PM
Are you seeing any weight reduction by machining your own head or ?
Cheers
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 17, 2012, 06:28:27 PM
Quote
Are you seeing any weight reduction by machining your own head or ?

Unfortunately no, the original head was very light (a few ounces).  The new one is probably 2 lbs or so.

The whole rocker arm set up is much closer to being finished... it should be done by next week.  Last Friday, we threaded a bunch of holes and put the valve guides in.
Title: Re: Treadmill Dyno Burnout 2
Post by: taylorp035 on March 18, 2012, 10:29:04 PM
http://youtu.be/ZaQUkauajjs (http://youtu.be/ZaQUkauajjs)

A daytime burnout on dry pavement.  Today's problem was a loose wire in the starter motor circuit.... but on the plus side, it was 75 degrees and 7 people got to drive the car!
Title: Re: Treadmill Dyno - More Engine Pics
Post by: taylorp035 on March 20, 2012, 02:50:55 PM
(http://i41.tinypic.com/6f3240.jpg)
Title: Re: Treadmill Dyno
Post by: SparWeb on March 20, 2012, 03:26:51 PM
Looks nice and simple.  Guessing that you don't need cooling fins etc because the engine runs only for brief periods.

Do I see chatter on the rocker arm ends?

Also, Heli-coil is your friend.  Use it anywhere you're threading a steel fastener into the aluminum.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 20, 2012, 03:45:40 PM
Quote
Do I see chatter on the rocker arm ends?

My little CNC machine isn't very rigid, but the other one came out good.  It could be from the programming too in the CAM softare.

Quote
Guessing that you don't need cooling fins etc because the engine runs only for brief periods.

Yep... we are actually thinking about insulated the whole engine to keep it warm.  When we run the car, the exhaust won't even burn your hand after 4-5 seconds.  There was a team last year with a plastic exhaust pipe, but the inspectors didn't like it.

Quote
Also, Heli-coil is your friend.  Use it anywhere you're threading a steel fastener into the aluminum.
That's a great idea.  Our smallest bolt is a 1/4-20 with over 1/2" of thread, so we should be fine, but on older blocks, we have stripped out some of the smaller threads.



Possible tomorrow night, I may get you guys a picture with the rocker's and the spark plug installed.  Later in the day, I took it to my last class and set on my desk to look at during class.... learning about gears and their safety factors can get boring at 4 in the afternoon on a sunny day :D

Title: Re: Engine Head Pics
Post by: taylorp035 on March 21, 2012, 07:59:09 PM
It's been a long time coming (~3 years...).  The last part that it needs is the extensions on the end of the push rods (the threaded guys in the back).
(http://i44.tinypic.com/bf5ez7.jpg)
Title: Re: Engine Head Pics
Post by: JW on March 21, 2012, 08:53:50 PM
interesting thats a L-Head engine block, is the head gasket round or does it have the clearance for the old engines valves.. Also if you have managed this, have you added the extra cyl head bolt that was not originally there. I see the valve guides are not angled like a hemispherical arrangement. is this so you dont need a relief on the piston top, and what is the compression ratio with the new cyl head.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 22, 2012, 11:36:36 AM
JW,

The head gasket is not round, but rather the shape  of the entire top surface, which has to seal the cylinder and the valves.  As for the extra head bolt where the intake area once was, no, we did not add another bolt. The rocker parts would kind be in the way and there is not very much material to sink an extra bolt into.  Also, you could loose compression through there.  The valves are straight and are positioned so the engine is a non-interference engine with no head gasket (according to the drawing), but the valves are actually a bit lower, so hopefully the head gasket is thick enough to make up for this.  The compression ratio will be 12.3:1 with a 0.060" head gasket, and 16:1 with no gasket.  More than likely, the connecting rod would break much past 13:1...   The stock engine was supposedly 6:1, which is very, very low and make a poor use of isooctane fuel (I think you can go up past 18:1 with it).

The valves, tappets, springs, and valve seats are from the original engine.  Everything in the block is the same.  The hard part was making sure everything was going to line up and that the head bolts were going to fit.  Simplicity was a high priority.  The really good teams that spend millions of dollars in Europe/Japan have hemispherical engines that are usually ~16:1 C.R. and dual overhead valves and two spark plugs on a 30 cc displacement.  Ours in 148 cc's.
Title: Re: Treadmill Dyno
Post by: JW on March 22, 2012, 06:21:13 PM
I have been working on a "four cycle steam engine" for years. The engine uses a direct injection valve that uses a briggs valve spring.

Im not sure if your allowed to use direct fuel injection, but I would be willing to donate a license for your team. US 6,928,992  US 7,552,715

http://www.flashsteam.com/L912_Injector.htm

-edit- I would recommend the SO8 not the L912, for direct fuel injection, the SO8 is miniturized version of the L912. I would also be interested in (also donating) development technical support, from machining (your machine shop) to electronic control. This is a direct electromagnetic lift valve not peizo. So you would rely on lift setting for throttling, not pulse width control. but the servo does use pwm -edit-

When im talking with other steam folks, they dont seem to make the connection of compression ratio to volumetric efficiency. For the steam applications 9.5 to 1 is considered high compression when compressing live steam, before injection duration.

I know this is apples and oranges to what your doing with the super milage.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 23, 2012, 12:23:03 AM
We are allowed to us direct injection, but basically, the engine needs to be a 4 cycle combustion engine.... so I guess no steam.  Some people talk about 6 cycle engines too, but I guess that would go against the rules of "4".

Here are the relatively simple rules if you want to see them:
http://students.sae.org/competitions/supermileage/rules/ (http://students.sae.org/competitions/supermileage/rules/)

Quote
When im talking with other steam folks, they dont seem to make the connection of compression ratio to volumetric efficiency.

Is it because there is a larger change in temperature after the power stroke, so the cylinder sleeve is cooler, thus more air can come in the next cycle?   I can see that the higher compression ratio would raise the cycle efficiency....


I sure do seem to find a lot of interesting people on this forum  :D  You never know who you will run into with these creative types of people....
Title: Re: Treadmill Dyno
Post by: SparWeb on March 23, 2012, 10:48:19 PM
Hi Taylor,
Another thought: Are your pushrods sliding through bare aluminum holes?  If so, a brass sleeve would reduce the friction, and allow tighter tolerances (sliding clearance) so there would be less noise vibration etc.  Getting the right press-fit to keep the brass sleeve in place is a bit of a chore on a "one-off".  Enough suggestions from me that make more work for you!
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 24, 2012, 06:12:35 PM
Sparweb,

We now have brass sleeves in there.  The some of the stock engines had no sleeves from the factory, just aluminum valve guides.
Title: Re: Treadmill Dyno
Post by: SparWeb on March 25, 2012, 08:21:54 PM
Ah just one step behind you!
Title: The Big Reveal
Post by: taylorp035 on March 31, 2012, 07:31:11 PM
The day you guys have been waiting for, the new engine now runs and I have pictures of the new car  :) :D ;D



(http://i40.tinypic.com/dg46zl.jpg)


EDIT:   Some more photos of the SAE supermileage car....

(http://i42.tinypic.com/bgu1qr.jpg)

(http://i39.tinypic.com/wrb7f9.jpg)

(http://i39.tinypic.com/zn38i.jpg)

(http://i43.tinypic.com/2cnjps5.jpg)

(http://i40.tinypic.com/25yxirq.jpg)

(http://i42.tinypic.com/2thlj.jpg)

Title: Re: Treadmill Dyno
Post by: electrondady1 on April 01, 2012, 10:26:00 AM
it looks fast
after you win the mileage  contest , maybe jack it up a bit, and take it to Utah?
it would look good with salt on it.
 
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 01, 2012, 12:49:54 PM
With the stock engine, the numbers suggest that you could hit about 100 mph on 3 hp :D   But the tires are rated only for about 40 mph....    Previous supermileage cars have been known to go past 50 mph   ;)  From personal experience, much past 35 mph is really scary on 3 wheels and your limited visibility becomes a factor.  Surprisingly, the car is quite stable, so it will usually understeer in a corner instead of rolling over.

As for salt, we loaded our old car with salt after driving it around in the slush around the school.... took all week to clean out of the engine bay and driver's compartment.
Title: Re: Treadmill Dyno
Post by: ghurd on April 01, 2012, 07:54:47 PM
As for salt...

Oh boy...  Kids these days.
The salt flats?  In Utah?

If you were NOT just messing with E-Daddy, I may have to drive up there and smack you with a perfectly flat salt block!
 :o
G-
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 01, 2012, 09:20:17 PM
No, I wasn't....  note the original burnout in the dark... the road had an inch or two of slush with salt mixed in it.  The driver had salt all over him when he was done.
Title: Re: Treadmill Dyno
Post by: electrondady1 on April 01, 2012, 10:10:11 PM
this is the place.


they bring  things there to go fast
(http://)
look familiar?
Title: Re: Treadmill Dyno
Post by: electrondady1 on April 01, 2012, 10:15:38 PM
(http://)

 taylor i  like your machines shape
it got me thinking, there is probably a scta category for briggs powered streamliners
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 02, 2012, 09:34:29 PM
A rear wheel steering setup can reduce your total frontal area by lowering the area needed for the front wheels.  I would also consider trying out so of the Solar Challenge tires, since they are wider and would have super low rolling resistance and since they are designed for higher speeds.  I bet you could get the drag coefficient down to ~0.08 or so if you tried.  I don't know what the Cd is for my new car or old car, but many other teams come in at 0.12 - 0.15 for the decent teams and  0.075 - 0.1 for the really good teams.  The frontal area for the best cars is less than 0.3 m^2 (extremely small).  My old car was 0.444 m^2 and the one before that was 0.75 m^2.

Of course, driver space is critical when designing these things.... as you will find that many of the top supermileage cars have less than 14" of width for the driver, if not 13" or even 12" where they sit between the front wheels.  A small driver though can fix many of these problems.


Here is our team site with all of our photos that we are now letting the public view.


http://behrend.orgsync.com/org/societyofautomotiveengineers22440/home (http://behrend.orgsync.com/org/societyofautomotiveengineers22440/home)
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 08, 2012, 09:29:52 PM
We put our new engine on the dyno last friday and even though it only was running at about a 6:1 compression ratio right now (head gasket is blown), we recorded several run north of 15.5% efficient!  Previous runs with the equivalent set up with the L-head were about 13-14% efficient.  Once we get our new spark plug and electronic ignition set up and a new head gasket, I think we can boost the efficiency a few more percent.... hopefully getting to 20+%.  If we could get much past that, I would say we could make a serious run at the North American mpg record  :)  The exhaust note is really cool, kind of like a hit and miss engine and the popping sounds they make.  This week, we will get a new head gasket, hook up the AFR gauge, add the ceramic bearing faceplate, and add the high performance spark plug.

We also made sure our new car is going to fit in the van we plan on taking to competition.... at 118" long, we knew it was going to be a tight fit to get it into a mini van...... to make it fit, we had to move the driver and co-pilots seat up a few notches   8)  The arm rests may end up being removed too on the front seats.

We also had all of the members try and fit inside of the new car.  Turns out that the new car is surprisingly spacious when compared to the last car, as my 6' 1" frame fit side with out cutting my feet off...   Visibility seems good enough to drive @ 15 mph on a 2-3 lane track with a car that is 24" wide  :-\

You can see how little space we have.... the carburetor doesn't even fit pointing towards the tire, so it's going to go towards the firewall.
(http://i42.tinypic.com/akc3gz.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 17, 2012, 12:57:15 PM
Things have moving along quickly in the last few days.  The front windows have been cut out and the front wheels mounted.  We were pleasantly surprised by the amount of reward visibility that we have.  The front wheels fit well too, especially considering that we have less than 1/4" of clearance in about 10 spots around the the tires and that everything is hand made :D   We also figured out that you should open the throttle all the way open while doing compression tests.... that way the air can get in the engine  ::)  Definitely felt stupid after figuring that one out.  Now we have 225+ psi of compression!

Next up is thermoforming the front windshield.  Unfortunately, the big machine that our school has to do such things woln't work for our application.  But we do have a 1800 watt heat gun and 3450 W of light bulbs, so maybe we can make something work.  Looks like we need to get it to around 310-350 F and keep it below 370F.

Title: Re: Treadmill Dyno
Post by: SparWeb on April 17, 2012, 02:14:59 PM
Taylor,
20,000 views!


Quote
Now we have 225+ psi of compression!

Do I read right, comp ratio = 16:1  (or 15:1 if that already includes atmospheric pressure)
Either way, Nice Job.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 17, 2012, 11:19:13 PM
20,000 Views 8)

With our 0.060" head gasket, it should be about 12.3:1.  0.040" = ~13.5:1, and 0.000000" = 16:1.  The compression could be higher if the volume calculations were wrong...

Tomorrow we plan on doing some dyno runs and seeing what the best the engine can do.  We also want to test to see how much better the engine is at wider throttle than idle (with a mostly closed valve in carb, which hurts compression).  If there is a huge difference, we can try the fuel injection to eliminate the restriction...
Title: Re: Treadmill Dyno
Post by: SparWeb on April 17, 2012, 11:59:58 PM
Tomorrow we plan on doing some dyno runs and seeing what the best the engine can do.  We also want to test to see how much better the engine is at wider throttle than idle (with a mostly closed valve in carb, which hurts compression).  If there is a huge difference, we can try the fuel injection to eliminate the restriction...

Here we go with the graphs again!
Title: Re: Treadmill Dyno
Post by: Bruce S on April 18, 2012, 09:12:47 AM
20,000 Views 8)

With our 0.060" head gasket, it should be about 12.3:1.  0.040" = ~13.5:1, and 0.000000" = 16:1.  The compression could be higher if the volume calculations were wrong...
Which head gaskets are you using? there are the standard ones and there used to be available (racing) head gaskets. In my younger days (when full service premium was 0.49/gal) we built them with these ultra-thin tin gaskets , if you have to stay with standard gaskets, grab one the is metal plated.
I will go out on a limb here and say I 'm sure you've already lapped the head and body top to be ubber-smooth?
Nice vehicle!! you're ahead of Chrysler :-) they're now using CF the lighten their Vipers!
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 19, 2012, 01:45:04 PM
Bruce,

Our head gasket material is has metal in it.  With the 0.040", the gasket makes up about 25% of the total compressed volume.... the chamber is only 9 cc.

I was wrong about the head gasket dimensions from last time...  we are currently running 0.040", which makes it a 12.3:1 ratio.  I was thinking of the numbers for next year's engine ;D   We did lap the valves and the head / block were both face milled at one point.

We were hoping to make the whole body less than 15 lbs, but it came out to 22 lbs due to several mistakes caused by our inexperience.....  it would be nice to have access to a professional shop and use their equipment like some of the other teams do.  With the frame, engine mount, wheel mounts, and windows, we will be at about 35 lbs, which compares to about 52 lbs in the old car or ~100 lbs from 2 years ago.

(http://i42.tinypic.com/34g91js.jpg)


Visibility is better than ever!  You can also see how nice the shape is   :)    I bet this new car has half the air drag of last year's.  It's also a bit more cozy in terms of space that is left over for components (engine, fire extinguisher, steering, electronics).

(http://i42.tinypic.com/nwg6bq.jpg)
Title: Re: Treadmill Dyno
Post by: Bruce S on April 19, 2012, 02:49:01 PM
I can now see why you kept the design under wraps !!
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 22, 2012, 05:57:32 PM
Last Friday, we spent a bunch of time trying to thermo-form our front window.  But all we have in terms of tools to heat the plastic (~24" x 36") is a hair dryer style heat gun (1550 W).  So we made ourselves our own oven with cardboard and high temp duct tape.  As for insulation, we used a combination of a large amount of cardboard and pink foam, but we found out that the foam melts at 240 F, well below the ~350F we needed to reach.  After 4 hours, we finally made enough improvements to our cardboard oven enough to hit 332 F with the heat gun and a 1800 W hair dryer.  Unfortunately, you need to keep the plastic above 320 F for it to be flexible and below 370F to prevent bubbles.  By the time we tore apart our oven and applied the plastic to the mould, it had cooled off too much.  We got the main curve in the window, but the 2nd axis curve (the side profile curve) did not happen.  We have a 2nd piece of plastic if we want to try again, but we may not have enough time to do so.

We also broke our steering in the front, so that needs to be fixed.  But on the plus side, we found a solution to our battery management issues to pass the rules.  We also ordered a new set of points for the engine, since we have vaporized the old ones in ~50-100 h of running it.  This was affecting our efficiency majorly.
Title: Re: Treadmill Dyno
Post by: JW on April 22, 2012, 06:15:49 PM
If you used some small gauge sheet metal instead of cardboard for the oven, then line it with fiberglass house insulation with another layer of sheet metal(with a door), you could get to your work piece out quicker using that door (without tearing apart a cardboard box) ,then the adjacent area you could use some 5/8 thick foam board and make a sauna room adjacent to the oven,(with a door also) steam it up pretty good and fashion your work piece on the mold in there.

Dry air around where your working is going to cool too quickly, and without some form of humitity control for the work area, when you fashon it to the mold it will be too cool. the mold should already be as hot as the sauna room. then when youve got it clamped down to the mold take it out of there to set.

JW
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 22, 2012, 07:14:09 PM
We have aluminum sheet metal, but no fiberglass insulation.  Our only insulation sources were layers of cardboard with some air pockets and the pink foam.  If we try it again, we will probably use some wood as the side walls and the support structure.   

Our cardboard over was hinged on the top so you could just open it up, but we had accidentally taped it shut while adding the various pieces of insulation.

Also, we had to make sure the edges of the plastic were not hot so we could grab it since we only had 5 gloves (and there were welding gloves, so it wasn't ideal).

You can check out the photos of it in here under the Build Photos (3):

http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures (http://behrend.orgsync.com/org/societyofautomotiveengineers22440/Pictures)
Title: Re: Treadmill Dyno
Post by: JW on April 22, 2012, 07:21:07 PM
Well in that case, I would submerge it into a pool big enough for it, and use heat transfer fluid with the temp you specify.

I guess your right its not really a good conductor of heat (the work piece) so you should have what you need.

Hope it goes well, you've solved simular problems in your posts here related to the project.


JW
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 22, 2012, 07:27:34 PM
A big deep fryer would do the trick   :D    Now where to find a deep fryer that we can use.....
Title: Re: Treadmill Dyno
Post by: JW on April 22, 2012, 07:45:47 PM
If you had a metal pan that would hold it(insulated outside), you could get 500°f  heat transfer fluild http://www.radcoind.com/Profile.html

You would need a pump like this  http://www.marchpump.com/809-br-brushtype  I have one of these and have heated the transfer fluid to about 345°f sustained.

The pump runs on 12 volt, and I would use a coil heat exchanger on the output to the tank.

Title: Re: Treadmill Dyno
Post by: taylorp035 on May 03, 2012, 09:18:55 PM
YAY!!!!!!!!!   Finals are done for, so tomorrow will be ~17 hours of non-stop supermileage time   :D

Earlier this week, we finished sanding the body (a good 15 man hours) which was extended another 2 hours since we got oil on the top of the car (shown below).  One of the bolts that was on our side plate cover (about a 1/2" diameter) wiggled loose and oil sprayed out of the engine while it was running....  the oil covered my laptop, a desktop computer, my brother's hand and the top of the car that was on the ground near by (which I had just finished sanding 2 minutes earlier).  Since you don't really want to paint over top of an oily surface, I tried to wash it off, but it had stained the lid real bad.  So another 2 hours of sanding was done with a DA sander.  But at least the top is extra light weight now....
(http://i50.tinypic.com/2rcqy4o.jpg)


We then weighed the car with the windows, top, frame, roll hoop and the body.... coming in at an impressive 31.2 lbs.  That makes it about ~6-7 lbs / m^2 of surface area.
(http://i45.tinypic.com/1e3p1i.jpg)


Next up was installing the engine with the reinforced engine mount (hoping to skip the turn buckle this year).  We also finished version 2.0 of the rear wheel mounts, with our radical carbon fiber lead springs.  They are about as stiff as a plastic fork, but they should hold the axle just fine and allow for an adjustment of ~1/2" forwards and back.  The rest will be tied down with an array of titanium and some turnbuckles.  The downside to this is that there is almost no room to get your arms in the back to assemble it... definitely a "no wrist watch" zone  :-\   Before sanding the car, it is kind of like sticking your arm into the sharp needles of a pine tree....
(http://i47.tinypic.com/6teavr.jpg)


As for space around the engine, I'll let the pictures do the talking.... note the missing carburetor (it doesn't fit right now...) and how close the flywheel is.
(http://i49.tinypic.com/a9ommw.jpg)

(http://i49.tinypic.com/abjomd.jpg)


There are many more places where the clearance is less than ~1/8", especially around all 3 tires.


Title: Re: Treadmill Dyno
Post by: taylorp035 on May 08, 2012, 02:11:40 PM
A fun photo from my CFD work on the car.  This new software that I have could work really well with designing and simulating a wind turbine.... assuming there was enough time to do so.  Autodesk Simulation CFD.

The large version link:
http://i47.tinypic.com/avg56q.png
 (http://i47.tinypic.com/avg56q.png)

640x480 version:
(http://i50.tinypic.com/mkc8s7.png)
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 08, 2012, 08:57:00 PM
The current car  :D   Check out the 462 kb high res photo.  1.88 N of drag @ ~15 mph.  I  need to make the wind tunnel a bit bigger so the air doesn't speed up so much around the car (currently the car is 3% of the cross sectional area of the tunnel...  should be around 1%).

High res:http://i48.tinypic.com/15hy9h3.png (http://i48.tinypic.com/15hy9h3.png)

(http://i49.tinypic.com/209myvc.png)


Next up is to make the road move below the car   :)
Title: Re: Treadmill Dyno CFD Fun
Post by: taylorp035 on May 09, 2012, 07:10:24 PM
With a bigger wind tunnel and a bit more computing time, the drag on the car went down to 1.32 N @ 15mph or a drag coefficient of ~0.14.  I think this value would be lower if I could model the road below the car.  Some photos:

(http://i48.tinypic.com/aonj7o.png)

(http://i47.tinypic.com/1tvor9.png)

(http://i48.tinypic.com/nq4r9w.png)
Title: Re: Treadmill Dyno
Post by: SparWeb on May 13, 2012, 08:54:48 PM
Quote
Before sanding the car, it is kind of like sticking your arm into the sharp needles of a pine tree....
* cringe *

Please be careful and wear breathing masks, gloves and long sleeves!
Even go so far as make yourself the "bad guy", and police the others on the team, for their safety.

In an industrial setting, the protective gear is a given, but in the college/university shop I do worry.

I should have taken a picture, but I was a bit too busy driving to the hospital, the day I learned THE HARD WAY what not to do with CF.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 14, 2012, 12:10:11 PM
We are always really careful with the dust.  We also use two large industrial air vents to pulls any particles out of the air.  Safety glasses are also heavily enforced.... especially when using a dremmel tool for cleaning the sharp stuff.  I've had my fair share of things hit me in the face to know that they are a good idea.

One of the tricky things is when you go glue more C.F. into the body using rubber gloves.  When you spread the glue on, you end up tearing holes in your gloves  :( 


Today we plan on test driving the car for the first time  :)
Title: Re: Treadmill Dyno Painted Car
Post by: taylorp035 on May 27, 2012, 05:12:08 PM
I think we did a good job on the paint, considering we had no professional help and all for about $60.

(http://i48.tinypic.com/f9pma9.jpg)

Initial testing is coming in at ~1000 mpg with the bad tires and several other things that aren't perfect.  2,000 mpg will be a stretch but certainly doable on the test track.  Total weight = 91.4 lbs.
Title: Re: Treadmill Dyno
Post by: electrondady1 on May 27, 2012, 05:32:02 PM
it looks great!
what a wonderful accomplishment for you and your class mates tayor
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 27, 2012, 06:23:56 PM
Thanks electrondady1!  The competition is only 11 days away   :D  Hopefully we can beat some of the Canadians this year (much credit to their teams for doing so well).
Title: Re: Treadmill Dyno
Post by: zap on May 27, 2012, 08:23:18 PM
Looks pretty darn slippery.  Nice job to all and best of luck in the competition.
Title: Re: Treadmill Dyno
Post by: SparWeb on May 28, 2012, 12:42:20 AM
Yes, I may (grudgingly) be cheering on a non-canadian team...  We'll see who's still standing after the first day  ;)

Checked the SAE website and wow:  32 teams.   Hurry up to be first in line at the refreshments stand or you'll miss out!

All the best good luck to you.
Title: Re: Treadmill Dyno
Post by: Bruce S on May 29, 2012, 11:29:42 AM
Very nice!!
Title: Re: Treadmill Dyno
Post by: DamonHD on May 29, 2012, 04:07:59 PM
Yes, very good indeed!  1000mpg?  Just got to convert a few SUV drivers and Peak Oil will vanish into the future again!  B^>

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 29, 2012, 11:05:03 PM
Thanks everyone!  I'm so glad that so many people are following our project.  I can't wait to get some official numbers.

Here is another photo for you guys, this time from the inside.  Note the awesome steering tiller/handle.  I'm really proud of how lightweight and compact the steering and brakes are.  In this photo, the wheel skirts are muddy from us test driving it (from the tons of road salt dumped on our parking lots every winter...).  When clean, you can can see right through the wheels for better visibility.  Everything is very carefully planned out.  The seat cushion and seat belt carefully hides the ~3" tall cross member between the kingpins and the tie-rod (many people are confused that we don't have a rack and pinion steering box).  But the most amazing thing is that everything fits considering that the whole car was laid out by hand... no cnc work here  :)

For sizing... those are 20" bicycle tires and the frame rails are ~12 3/4" wide (this car is much more comfortable for narrow people).

(http://i47.tinypic.com/vdntxz.jpg)
Title: Re: Treadmill Dyno
Post by: Frank S on May 30, 2012, 07:20:00 AM
Taylor I apologize if I seem to hi-jack your thread for a second.
 But Steve; low RPMs is not always the best solution to higher mileage.
 If the vehicle you have in question wanting to drop the RPMS to 1200 or thereabouts is a diesel then by all means it is worth a try however even  most diesels torque curve works out higher than 1200.
1200 on a gasoline engine except for some 50 gallon piston monsters is far below where automotive engines develop their sweet spot, which is usually near the middle or as low as the 30% mark where the curve goes dead flat
 an example My wife used to own a 91 ford ranger pickup 5th gear on flat ground @ 70 would not get her any better fuel economy than  4 th gear @ the same speed. usually it was much lower millage as she had to push a lot harder on the pedal to maintain 70MPH.
 Last year while on holiday I rented a VW polo diesel for 2 weeks then the same model car with a gas engine I was traveling in Spain lots of mountain driving. 5000 Kilometers on each car the diesel averaged 30% better fuel millage over the gas. I had to constantly down shift even into lower gears to maintain speed with the gas engine where as with the diesel I might have to drop into direct occasionally on the worst climbs for highway driving.
 Taylor I am trying to visualize 18 to1 comp on an engine like you have and I am wondering just how lean the air fuel ratio could go with the fuel injection system before destructive forces take over.
 I know that the model airplane engines can achieve an absurd A/F
Title: Re: Treadmill Dyno
Post by: SparWeb on May 30, 2012, 10:51:52 AM
Frank, I was confused at first, reading your comments.  Are you picking up on comments made by MadScientist, in December?  I can find that on page 8 of this story.  It's helpful to other readers (not to mention Steve himself) if you click the "quote" button on a particular comment before following up on it.  That preserves the context and saves any other reader from scrolling back pages to find an old comment.

As for the comments you make now, Taylor's car isn't a diesel and 90% of the time its engine is off.  Hard to make comparisons with your Polo.  I don't think this car needs much speed range, either - it drives at the same speed around the track the whole time.  So far as I gather, at least.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 30, 2012, 12:21:11 PM
Let me set some things straight  here....   The operating range for the engine is to run for about 3 seconds going from 1500 to 3000 rpm (basically doubling our speed from 10 to 20 mph or so).  We have tested our engine over the various rpm ranges and have found the efficiency stays fairly flat in that rpm range.  Much higher, say 4000 rpm, efficiency starts to go back down.  Interestingly enough, the speed at which the car drives is even a stronger relationship than the curve of the engine efficiency, so it's in our best interest to drive it at the right speeds.

Our compression ratio is currently about 13:1, which is just fine considering we are using iso-octane fuel.  The only hard part is that this puts more stress on the starter motor, especially with our super light weight flywheel.  If there is no load on the engine, the engine will spin up as fast as you could imagine an engine doing so.

Our engine isn't particularly efficient... based on our somewhat crude testing, we figure ~15-17 %, compared to maybe 25-30% for a normal car engine.  At stock engine that we start with is somewhere around 12-14%, depending on AFR (lawnmower engines run way too rich for supermileage use).

The major trick to getting good mileage is not running the engine the whole time.  If we just idled our way around the track, we might get 200-300 mpg.  If I wanted to keep the car going at a steady 15 mph, we would need about 50 watts or so, plus a boost of 1/2 hp for going up a 1% grade.

We are using a carburetor on our engine this year because it's simple, lightweight and effective...... we have an EFI set up, but have found it unreliable and not as efficient (10% for our testing, but it wasn't running very good).

Title: Re: Treadmill Dyno
Post by: Bruce S on May 30, 2012, 12:46:23 PM
Let me set some things straight  here....   
Thanks for re-posting those, with there being 9+ pages , it might be a stretch for others to go back through the earlier info.
Slick looking paint job too!
Bruce S
 
Title: Re: Treadmill Dyno
Post by: Frank S on May 30, 2012, 07:31:54 PM
Frank, I was confused at first, reading your comments.  Are you picking up on comments made by MadScientist, in December?
Sorry yes  I was probably referring to a post several pages deep. and had posted it before I had checked it .
I used to have a little neighbor kid that had a mini bike with a 3 hp Briggs his carb was really messed up from him constantly tapping on it to un-stick the float One day his dad brought it to my machine shop along with a carb off of a Honda 90 and asked me if  I could adapt it to fit and make it work.
 I explained to him that the brigs was a lot larger displacement but lower overall HP and not to expect any miracles but it did run, and also ran just fine it even ran over twice as long on a given tank of gas.
 this was 30 years ago and no power curve or any other testing was done just a very happy 8 year old terrorizing the neighborhood on half the fuel. 
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 30, 2012, 09:04:14 PM
The carburetor we are using is sized for an engine in the ~15-20 hp range (my Timberwolf 250cc 4-wheeler has one just like it).  Granted, the slide valve that lets the air in is much less than 25% open... at idle it's maybe 3-5% open.  This proves why we should have an EFI system so we can lower the pumping losses, but this is why we try to run the car at maximum power (and the tests back it up).

We bought a 50 cc carburetor and found that it didn't like the 148cc, even at idle.  But we may use it next year on a de-bored engine
Title: Re: Treadmill Dyno
Post by: Frank S on May 31, 2012, 04:25:05 AM
The carburetor we are using is sized for an engine in the ~15-20 hp range (my Timberwolf 250cc 4-wheeler has one just like it).  Granted, the slide valve that lets the air in is much less than 25% open... at idle it's maybe 3-5% open.  This proves why we should have an EFI system so we can lower the pumping losses, but this is why we try to run the car at maximum power (and the tests back it up).

We bought a 50 cc carburetor and found that it didn't like the 148cc, even at idle.  But we may use it next year on a de-bored engine
when you go to the EFI will it be a throttle body system of will you rework the head and opt for direct injection.
 I can see merits for either system But anything that significantly reduces the droplet size for a better fuel air mix allowing the air ratio to be increased should yield good results   
  Does the rules in your "class" allow for positive pressure air induction. I was thinking that the  "car-PAC II" (I think that was its name)  that holds the 12K + record was forced air as well.
 I like your thoughts on the Fred-Flintstones brake simple enough to have  section of the floor with a layer of dense  rubber  that is forced to the ground  not sure about the rules on that though
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 31, 2012, 10:24:12 AM
We can do anything to the engine we want, as long as we use the block in some fashion and the crank bearings stay where they are.  We own a turbocharger that we may try using in the future....    You could do an Atkinson cycle too if you want.  I'm not sure what a "positive pressure air induction" system is but I will look into it later today.


Funny you mention the Fred-Flintstone brakes... we actually tried it with our old car.  It didn't really work but the thought of mounting some titanium to the bottom of the brake pad was suggested a few times  to make some sparks  :)
Title: Re: Treadmill Dyno
Post by: Frank S on May 31, 2012, 02:32:27 PM
We can do anything to the engine we want, as long as we use the block in some fashion and the crank bearings stay where they are.  We own a turbocharger that we may try using in the future....    You could do an Atkinson cycle too if you want.  I'm not sure what a "positive pressure air induction" system is but I will look into it later today.


Funny you mention the Fred-Flintstone brakes... we actually tried it with our old car.  It didn't really work but the thought of mounting some titanium to the bottom of the brake pad was suggested a few times  to make some sparks  :)
the Atkinson cycle in such a confined engine block might be tough to achieve any benefits,
  Positive pressure air induction could be done with a retractable or pair of retractable scoops on the side or near the front of the vehicle they would need to close and be perfectly harmonious with the rest of the surface area when the engine was not running other wise it would create drag. you could wind tunnel the machine to determine just how much actual pressure could be obtained before the advent of added resistance out weighed the flow the engine was receiving
  Since your engine is only operated for such short periods of time by the time enough exhaust gas flow would be created to spool up the turbo to raise the intake to a positive you would be shutting off the engine. For this reason I thought of the positive induction the slipstream air would be diverted directly into the engine. your engine has to get intake air from somewhere why not use a couple of magnetic solenoids to actuate an induction scoop . you might not get full positive due to the low speeds of travel but theoretically better than having to suck every CC of air into the engine.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 31, 2012, 05:10:24 PM
That's a very interesting idea that could be done fairly easily, since the electrical circuit is already there for a solenoid.  I have seen similar setup on solar cars for when they need to turn..... their wheel skirts open up to make more room for the front wheels to turn.
Title: Re: Treadmill Dyno
Post by: Frank S on May 31, 2012, 09:00:26 PM
It might warrant a simplified mock up model tunnel tested before any modification to an actual car, a whole lot cheaper to scrap a few pieces of curved panels and duct work connected to the engine on your home grown dynamo than screwing up a car if the tests didn't pan out
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 02, 2012, 05:15:52 PM
Yesterday we did some more testing, even though it was dark outside and raining  8)   The pulled off an official 773 mpg but it equals ~1150 mpg due to the hill it was driving up, which isn't too bad considering the lack of traction (smooth bike tires on asphalt), the windy conditions, and the fact the testing place is only about 0.35 miles in one direction.

I did a few calculations based on the real performance on last year's car at the proving grounds, and I figure this car should do at least 1850 mpg and no more than ~2,600 mpg, plus or minus a 100 mpg or so for the uncertainty caused by the different tires.

We did break our rear wheel mount yesterday, but no worries, we fixed it so it won't be going anywhere :D  The part that came loose is a 3/8" thick titanium rod that's 6" long.... we were tempted on replacing it with an aluminum rod of the same size, but after a few calculations, we decided that it wouldn't hold up to the ~500 lbs of load that is caused by the running engine.

 I also found a bolt that was rubbing on our rear tire spokes.... good thing I caught it, else there could of been a bad breakdown at the track.

The only thing that still worries me at this point is how much power we are using on the starter motor.  Last year's car only used 300 mah, but during 3 miles of testing, this year's car used 1,000 mah, and we need to go 9.6 miles on ~1200 mah (ideally 1000 mah or less).  Since our starter battery is not regulated, I can put a bigger battery in the car with 2200 mah, but that will cost us another 100 grams or so and make things a bit more complicated for charging batteries (currently our accessories battery and starter battery are the same battery, so they can be swapped).
Title: Re: Treadmill Dyno
Post by: Frank S on June 02, 2012, 07:21:04 PM
  Since our starter battery is not regulated, I can put a bigger battery in the car with 2200 mah, but that will cost us another 100 grams or so and make things a bit more complicated for charging batteries (currently our accessories battery and starter battery are the same battery, so they can be swapped).
No problem just don't let the driver eat for a couple of days or figure out how to have him toss his cookies after weigh in without being caught  Just Kidding
Title: Re: Treadmill Dyno
Post by: SparWeb on June 03, 2012, 05:20:03 PM
Yesterday we did some more testing, even though it was dark outside and raining  8)   ...
We did break our rear wheel mount yesterday....
 I also found a bolt that was rubbing on our rear tire spokes....
The only thing that still worries me at this point is how much power we are using on the starter motor.  ....

You are so far a head for having left yourselves enough time to do this testing!!
Many many years ago (sorry) I arrived at the college's robotics competition with a completely untested robot.  All kinds of silly errors cropped up.  Things that would have been solved if only we'd given a few days' time to testing it out properly.  We did well at the competition mostly because many other teams were equally under-prepared.
Title: Re: Treadmill Dyno
Post by: Frank S on June 03, 2012, 07:34:40 PM
What was that about the 5 "P"s  I used to drill into my students minds as a PsyOps drill instructor OH yes, Prior planning prevents p*** poor performance & death in many cases
 These guys building this car have done their homework and more importantly their lab work and it is clear to see that they are in it for the long haul I wish them all the best
Title: Supermileage Results
Post by: taylorp035 on June 09, 2012, 09:07:45 PM
The official results:  1485 mpg, which was good for 1st place  :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D :D 8)

More on this later when I have the time to post more.
Title: Re: Treadmill Dyno
Post by: electrondady1 on June 09, 2012, 09:28:10 PM
wow,
you guys won!

nothing sweeter than victory.
congratulation !
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 09, 2012, 10:00:33 PM
Thanks!  It was surprising that we were able to win with such a low score.  I was expecting the winner to get at least 2000 mpg, but many teams struggled to get their cars running well (only 9 cars had a successful run).  There were a lot of teams that just didn't show up, which seems odd considering the attendance from previous years.  On test day, we measured 3 test runs for mileage and our best was 1,777 mpg on 3 laps.  But on race day, the car was rolling just a bit less good, the winds had changed, and we think the AFR ratio was messed up for our first 4 runs.  At that point, we made a major adjustment to the carburetor and the numbers went from 1219 and 1203 to 1485 mpg.  I imagine that our engine wasn't as efficient as it could of been.  At the start of the 1485 run, our driver did a massive 20-25 ft burnout off the start line  ;D  That poor rear tire had zero rubber left on it by the end of the day, but amazingly there was no signs of little rocks trying the puncture the tire, even at 80 psi.  The tubeless tires worked well all day, even though we were loosing about 15 psi between runs.  Also on the 1485 mpg run, our driver averaged 15.039 mph, which means that she was off by only 6 seconds over 38 minutes of driving!

We also won the best design report / presentation and we were first through tech inspection.  Our only tie up in the inspection was that our rear tail light didn't have 6 square inches of visible area when looking at the car from straight back.  The fix was using a dremmel tool to cut out more carbon fiber from around the  tail light and covering the hole with packaging tape.  We were also the only car there with lithium batteries, since the other teams didn't want to mess with complicated rules that were associated with running them.

From a design point of view, our car preformed quite well, as the good aerodynamics and low rolling resistance were visible by how far the car rolled.  The rear drive belt fell off on our first run and it took us about 90 minutes to realign the rear axle.  Our battery management units caused us to have two failed runs and probably killed one of our 65C Lipo batteries :(

I have to also say that everyone there was super friendly and helpful both days, especially Brigham Young University.  Their day ended after two good runs with a friend engine management unit.

(http://i47.tinypic.com/2mms41u.jpg)
Title: Re: Treadmill Dyno
Post by: SparWeb on June 10, 2012, 12:47:50 AM
(http://www.rigel.ca/gifs/highfive.gif)

Yahooooo!

(http://www.rigel.ca/gifs/anim_bounce.gif)
Title: Re: Treadmill Dyno
Post by: Frank S on June 10, 2012, 02:40:45 AM
good on ya
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 10, 2012, 05:22:03 PM
(http://i45.tinypic.com/2iuqlpx.jpg)
Title: Re: Treadmill Dyno
Post by: Bruce S on June 11, 2012, 12:34:59 PM
YEAH!!!!
!!!!CONGRATULATIONS !!!!!
Title: Re: Treadmill Dyno
Post by: Frank S on June 11, 2012, 12:48:18 PM
   At the start of the 1485 run, our driver did a massive 20-25 ft burnout off the start line  ;D  That poor rear tire had zero rubber left on it by the end of the day,
Did you get first place for best burn out as well? this ought to show the AA fuel dragster guys the you don't need 1500 HP to do a spectacular burnout.
 Next year try for a wheelie 

 I can just see the stats now 1st in MPG 1st of Show , record burnout , best & only wheelie
 maybe we need to think about getting you some wrinkle wall tires
Title: Re: Treadmill Dyno
Post by: SparWeb on June 11, 2012, 03:36:03 PM
... at next year's Supermileage Tractor-Pull.
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 11, 2012, 09:15:41 PM
We have had the car on two wheels before going around a corner  :)  Also the car did a drift on the back corner of the track in an evasive maneuver....   The 2011 car has been pushed to the point that it understeered... quite scary on 3 wheels.

Quote
... at next year's Supermileage Tractor-Pull.

Yep... add some wheel weights on it and hope that the super skinny 13g spokes don't break ;)
Title: Re: Treadmill Dyno
Post by: zap on June 11, 2012, 09:29:26 PM
Congrats to you and the team!
Title: Re: Treadmill Dyno
Post by: Frank S on June 12, 2012, 02:18:29 AM
Where can I download copies of the rules and spec sheet guidelines or previous white papers for the various classes of competition?
  Every year 3 of the Universities over here send me a cadre of students for real world OJT they stay for 1 month through the summer a project such as this could keep them out of my hair, then maybe I could focus on my designs without having to spend 45 minutes out of every hour explaining things to them that they will never be able to grasp without hands on trial & error experiences
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 12, 2012, 10:29:08 AM
Here are the rules Frank:

http://students.sae.org/competitions/supermileage/rules/ (http://students.sae.org/competitions/supermileage/rules/)

The main rule is goes something like this:  "Everything must be done in the spirit of supermileage (aka no cheating)"  Also, don't skimp on any of the safety rules, as they will call you out on it during the tech inspection.
Title: Re: Treadmill Dyno
Post by: Frank S on June 12, 2012, 06:07:06 PM
Thanks for the link I could see right off any project such as this would never fly for the students over here. This years crop of so called mechanical engineer wannabes would have difficulty designing a soap box racer to compete against a  a cub scout troupe. these are all 4th year students. the thing that tells me they will never be worth the amount of sand it would take to cover their bodies. is not 1 of them could tell me what the free flow ratio of 1" or 25mm id pipe to that of 2 " or 50mm pipe so I asked them if they had a 20 tooth driving sprocket turning @ 1000 rpm how me teeth would their driven sprocket need to be to get  250 rpm output?  I got answers of 40T and 100 T. I mean give me a break I makes me want to move back to Papua New Guinea
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 13, 2012, 06:50:40 PM
My advisor gave a different problem..... " If you had a rotating shaft with 15 hp input and you have a set of gears in the middle of the shaft taking 3 hp off, how many hp is left at the end of the first shaft.  Obviously the answer is 12 hp, but students today are not taught in such a why to make this obvious.  And to make the problem more interesting, you needed to understand this before you could solve the wear on the teeth of a gears.

On a more complex side of things, here is the distilled notes for improving our supermileage car engine for next year.... some of this has particular importance towards the idea of using a rotating pipe for the valves.  Basically, I have had the luxury to bury my face in an engine design and fundamentals book for the last 2 days  :)  Also remember that this engine has a very low design life, runs on 100 octane fuel, and will run for less than 30 seconds at a stretch.  Efficiency is everything.  And hopefully it won't spin the rear tire with ~ 50 lbs on it.
,
•   Put the fuel injector close to the intake – Less likely for the fuel to end up on the sidewalls of the intake
•   Possible Miller Cycle with rotary pipe – choose valve timing to eliminate some of the pumping losses
•   Longer Stroke than bore -  better thermodynamics, better at low RPM’s, keeps mean piston speed up.  (piston face area is r^2, sleeve area is just r)
•   If turbo is used, place as close to the exhaust as possible for maximum energy recovery
•   High Compression Ratio -  faster burn, less left over exhaust air, higher theoretical thermodynamic efficiency
•   Dual Spark Plugs – less burn time  higher pressure and temps
•   Intake diameter needs to be relatively small for carbureted engines
•   Use EFI, else carburetor needs to be run near WOT
•   Keep intake warm for better fuel vaporization
•   Smooth intake for high velocity power (not for us), Rough intake for low speed running, which helps cause more turbulence (causes better mixing on a levels). Pg 194
•   Mechanical losses go way up at higher engine speeds, therefore, the best efficiency is somewhere is the middle of the rpm band, if not slightly less.  Also, most engines have their best efficiency at ~75% of their max torque at the near middle rpm.  Definitely don’t go high in the rpm band or low in the torque level.
•   We should close the intake valve slightly earlier than stock since we are running the engine slower (pg 195)
•   No EGR valve
•   Combustion chamber shape is very important to tumble, swirl, and squish
•   To get more swirl, you can have the air come in at a tangent to the cylinder, which could easily be achieved by offsetting the rotary pipe. Pg 252
•   Dish the piston – as the swirling air is compressed, the radius is lowered from the outside wall to the diameter of the dish, causing the air to rapidly increase the rate of swirling due to the conservation of angular momentum.  A dish like the GX35 should work well for this.  Pg. 254
•   Lean mixture  slower flame  more pressure later in the stroke.  This may or may not be better
•   Tumble – the cylinder heads on the Cummings engine in the hallway have a deep almost squarish dish, this causes tumble
•   Pg 315-318 Theory on Exhaust Timing
•   Pg 321 Exhaust temperatures
•   Pg 373 Engine temperatures, commonly found
•   Stoichiometric AFR is 15.1:1  Energy Values are in the back of the book
•   2 Pressure rings instead of 3 due to the low RPM of our engine.  Maybe even 1 pressure ring, since removing one ring could increase the engine efficiency by 1% (~7% of the mechanical losses).  The oil ring provides almost no pressure resistance.
•   Possible oil additive to keep oil on surfaces  less start up friction
Title: Re: Treadmill Dyno
Post by: Frank S on June 13, 2012, 09:11:08 PM
Aw Gee maybe that is why we use a serpentine belt  and accessories that rob less power today than back when every accessory had its own "V" belt less power used means more power available LOL

 I had a friend who had dabbled with the miller cycle valve train nice high performance values but horrible train life sealing was his main problem even with very high end ceramics or titanium.
 for a while I was doing some work on a bent axis piston rotary the cylinders were the valves as well using slotted bores like a 2 cycle I think it would have delivered good power but low performance in both reliability and efficiency
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 13, 2012, 10:13:38 PM
The cool part is that we don't need a new camshaft in our new engine to change the ""valve timing"" and making a new rotary valve can be quickly made on a 4-axis lathe or cnc mill.

We will probably use a mxl timing belt for the drive on the rotary valve... i have seen the extreme cars to even have carbon fiber timing pulleys.

I'm hoping for carbon fiber steering too... I'm thinking another 2-3 lbs could be cut out.  And maybe C.F. axles all around  :)
Title: Re: Treadmill Dyno
Post by: Frank S on June 14, 2012, 07:07:42 AM
Another cool thing is it is a single cylinder, the duration overlap & timing,  if using separate valve shafts is a matter of opening width or length, the degree of the sprockets can be set independently. Combustion chamber design is critical with the rotary valve though.
 But you guys seem to have a good handle on being able to figure out things like that.
 I agree that you will want longer stroke to bore ratio better for lowering the RPMs of the lower end of the torque curve
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 15, 2012, 08:11:35 PM
I was surprised at competition that the rocks didn't penetrate our tires at 80 psi... I guess we will have to try harder next time :)  100 psi on tires that are as flimsy as 3 sheets of normal paper is quite trusting of the engineers at Michelin (they claim 50 psi...).
Title: Re: Treadmill Dyno
Post by: DamonHD on June 16, 2012, 02:07:22 PM
I'm late to the party, but just Wow!  Well done!

(Of course it was FL that made the difference!  B^>)

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 16, 2012, 07:19:18 PM
Thanks DamonHD, and everyone else who has been following my project.  I guess it shows that you can do something technically great without large amounts of money.

Quote
(Of course it was FL that made the difference!  B^>)

I guess it does get the project out on the internet if anyone was trying to search for it.  There are only a handful of teams (probably less than 5), that have all of their information out in the open.
Title: Re: Treadmill Dyno
Post by: SparWeb on June 18, 2012, 12:24:33 AM
I guess it does get the project out on the internet if anyone was trying to search for it.  There are only a handful of teams (probably less than 5), that have all of their information out in the open.

How much thought and discussion was there among the group about this?  Were other team members blogging their experiences?  Did others prefer to stay quiet?  I'm not asking for dirty laundry, but I am wondering if the decision to write and publish your info was contentious - if so, how did you deal with it?
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 18, 2012, 10:41:17 AM
Quote
How much thought and discussion was there among the group about this?  Were other team members blogging their experiences?  Did others prefer to stay quiet?  I'm not asking for dirty laundry, but I am wondering if the decision to write and publish your info was contentious - if so, how did you deal with it?

Interesting question.  Definitely one I have thought of before.  There was really only one other person in our group that was concerned initially about me posting the information, but our group is more of a club and we try to be friendly to the other teams.  Some teams are really uptight and won't let you take pictures or get close to their cars.  The main thing that we kept quiet was the design of our new body, but by the time we actually made it, it was late enough in the year so nobody could copy us, not that it would be easy to do so....   As for getting good mpg (2000+ mpg), I would say all of the teams understand the concept, but half don't know how to actually pull it off.  Then maybe 25% have half of the things right, say a good body, light weight, but then they will put bad tires on their car and ruin their chances.  Then there are ~5-6 teams who do know how to get 2000+, but due to budgets, personel, and the kids behind the program, they fail one of the required things.  If you get tires, an engine, a lightweight and aerodynamic body, a simple efficient drive train, and do some math to figure out the optimum driving strategy  (and then actually pull it off...), getting 2000 mpg is easily attained.  This year, our engine was efficient, but not in the ~1/2 hp range where we were running it, so that hurt our numbers.  Everything else, I would say we got a 10/10 on.

As for why I publish this stuff.... I find it fun to show off a project that I am truly proud of.  Earlier on, I asked a few questions to the FL people on the engine, but that didn't yield a whole lot.
Title: Re: Treadmill Dyno
Post by: DamonHD on June 18, 2012, 01:16:25 PM
Well, I'm glad you kept FL posted however much or little FL input was used, because it's great to see a project where the challenge is "how little" not "how much" IMHO.

I've spent a lot of my work improving software performance for banks, or efficiency, and really they are two sides of the same coin, doing more with a given bunch of hardware and energy.

Roll on the day that keeping up with your neighbours is all about how efficiently you can have fun, not how wastefully, though I suspect that basic sexual selection works against that hope!

Rgds

Damon

Title: Re: Treadmill Dyno
Post by: taylorp035 on June 18, 2012, 03:27:33 PM
This year I got to see inside of some of the Canadian team's cars, and I was somewhat disappointing.  I was impressed by their structural layout of the car and good use of carbon fiber, but the engines, drive trains, and accessories in the back of the cars were all way too complex and heavy.  Our car was super simple so nothing could go wrong (hence why we won this year).  Running jack shafts and complicated gearing systems is not a good way to make things lightweight and efficient.

But I will probably eat my words for next year, since there are big plans for EFI, a complicated mini engine, a complex battery management system, and a powerful touch screen computer that will help the driver get better gas mileage.  The plans call for the computer to be its own entire senior design project...  I'm hoping for a speedometer accurate to 0.01 mph average and updating at least 10 times a second, auto cutoff for the engine, lap counter, suggested start speed (with "timing lights" like at a drag strip or on the tach of a BMW M3), average speed to at least 0.01 mph, acceleration sensing for maximum use of our engine, traction control (so the tires don't vaporize), and possible some accurate gyro's for detecting the slope of the road so we can determine how well the car is rolling.  Also a live update on the remaining % of energy in our batteries.  And if convenient, a readout of the air fuel ratio.   And since this will be a 7" 1080p touch screen, there will be less buttons to mess around with.... and you could watch a movie I guess :)

There was a team two years ago that did something like this, including a wide area wireless network so people on the edge of the track could analyze the ~30 sensors that they had (I think their engine would even account for the temperature and humidity in the air...).

We don't have exact data on this, but I think having an expert driver who can hit the lap times perfectly instead of someone who has a fast and then a slow lap to average 15mph, will get ~5-10% better fuel mileage.  We have somewhat proven this the last 3 years, and my excel calculators seem to agree.

Here is the information that Laval gave out today... I used google translate, so some of it doesn't quite make sense.
Quote
Jun 11
First day at the 2012 SAE Supermileage
News Send feedback »

Good news, technical inspections and testing on the track have been completed. Early morning, we arrived at the site of the competition to prepare the vehicle for inspection. After a few adjustments, we went on an inspection, where apart from a few small modifications, all went well. In doing so, we were able to attack the track for a single round due to time constraints.

The evening ahead is dedicated to test the engine code as currently it does not achieve the desired speed for testing. We are still confident of finding the required values ​​and thus be able to save during the tests tomorrow.

More news will follow.

Jun 12
Last day of the SAE Supermileage compétation 2012
News Send feedback »

The final day of competition began with a vehicle preparation to go on the track: Warm up the engine, inflate tires and of course still some small problems to solve. We were finally able to make our first attempt in late noon. Air leakage through the head of the engine due to a candle that has ruined unscrewed however this test. The whole team is then lifted the sleeves and the problem was solved in time to give us a second time on the track. Everything indicated that this test would allow us to achieve superior results, but for reasons yet unknown the result was below expectations of the team. Finally, the all or nothing has been attempted in a last attempt to track that has not been successful because it is done in just two rounds to complete the competition.

The best recorded consumption of 1050 mpg combined score of the design competition has still allowed the team to get the third place in the competition. Despite the glitches encountered, the experience for our team mostly composed of new members has been most rewarding. We gratefully acknowledge the support of all our partners without whom none of this would have been possible.
Title: Re: Treadmill Dyno
Post by: zap on June 18, 2012, 07:19:01 PM
Candles that have ruined always seem to mess up my mpg too ;D
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 18, 2012, 07:37:51 PM
LOL.   ;D  I wonder what they really meant...  you can find the french version by searching "Laval supermileage"
Title: Re: Treadmill Dyno
Post by: zap on June 18, 2012, 09:32:10 PM
I do believe "bougie" can also mean a spark plug.  My guess would be "a lose spark plug ruined the test".
Title: Re: Treadmill Dyno
Post by: Frank S on June 19, 2012, 04:39:47 AM
candle or more accurately candela  Italian, bougie French/ Dutch,  Zündkerze German, bujia Spanish
no matter what you want call it, a Spark plug (sparking Plug) a device inserted the closed end of a chamber for the express purpose of delivering a highly energized electrical charge, said electrical energy is discharged at a termination point in the form of an electrical arc thereby igniting a mixture of compressed volatile and accelerating oxygenated combustible gases releasing ionized expanding energy.
     
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 29, 2012, 10:27:08 PM
I'm thinking our entire front frame, steering assembly, tie rod, wheels, brakes, tires, and axles will weigh less than 5 lbs.... most of it is in the drum brakes.  I'm thinking everything else is going to be carbon fiber, including the steering brackets and the axle  :)  Cross drilled drum brakes anyone?  The tie rod may stay as a piece of aluminum since it was pretty much as perfect as a piece of metal could be... unless they make magnesium tube the size of a drinking straw. We should be able to cut a good 1-2 lbs out of the front this way.  Then loose another 10 lbs in the body, fairly major when it started at 22 lbs (no filler this time 8)).  Lighter windows, cross drilled everything else and more aluminum bolts.  Goal: 70 lbs... and I bet it's possible.

This year's engine efficiency after working the numbers backwards:  8%   ???    Looks like our flywheel dyno results weren't lying!  Oh, well, I guess running the engine in it's most efficient power band was much more important.  And who would think that a car that gets 1485 mpg has too much engine   ;D  The good think is that we get another chance next year... a 20% engine wouldn't be out of the question, since we were at 17.2% at one point this year.
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 06, 2012, 09:37:19 PM
I figured it is time for an update for the start of the 2012-2013 school year.

Design work for the new car is moving along at a feverish pace.  According to our most recent CFD models, our new design is 18% better than last year's car  ;D  We also have a few companies lined up for sponsoring the car, which is never a bad thing  :)   We really want to break the North American record of 3169 mpg, which actually is well within reach if we use the best tires, have a slightly lighter and more aerodynamic car and an engine that is maybe 12-14% efficient.

And if other teams are looking at this.... this is not the final version of the design, nor would this be feasible to make into a car since it is too small in many areas.

Large version of photo

http://i49.tinypic.com/2qk1dzs.jpg (http://i49.tinypic.com/2qk1dzs.jpg)

(http://i50.tinypic.com/2zhpog8.jpg)


More computing power would be nice to have access to for doing these simulations.  4gb of ram really limits things. 8 or even 16 Gb would be much better, with a 3+ ghz quad core.  We have tried running the program on two 8 core computers, but it only uses 4 cores.  Usually its a minimum of 2 hours for a simulation to run, with some going on for 24+ hours.
Title: Re: Treadmill Dyno
Post by: SparWeb on September 07, 2012, 10:57:46 PM
Can you speed it up with a coarser mesh?
It's set to "auto" as I see on your full-size screen shot.
Sometimes you can sacrifice accuracy for speed when making early comparisons, then refine the winning choices later.

Inches and BTU's per second?  Even the british don't use BTU's any more.  ;)
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 08, 2012, 04:31:02 PM
Can you speed it up with a coarser mesh?
It's set to "auto" as I see on your full-size screen shot.
Sometimes you can sacrifice accuracy for speed when making early comparisons, then refine the winning choices later.

Inches and BTU's per second?  Even the british don't use BTU's any more.  ;)

The simulations would run faster with a coarser mesh, but that really isn't a big concern... it usually takes me ~3 hours to make a significant drawing change anyways, so I'm not really in a big hurry.

The mesh is set to auto, but then I put a second condition in saying that the mesh size directly around the car should be smaller (1.5").  Far away from the car where it doesn't matter, the mesh size is approximately 6-7".

I don't really care about the units since I can change the units on the results to metric... plus, my air speeds are in mph to make things easy.

After last night's meeting, we found out that the old model wasn't very representative of the actual old car.  So today I plan on making some more changes to the new model to make sure everything fits.  We in particular found that the new model was about 4" narrower at the crank shaft.... and as you guys could guess, we don't have 4" to give up.

We also drove the car around some last night.  It did a really good burnout + launch, which was all recorded on a video camera strapped to a homemade RC helicopter (well actually a tricopter).  The impressive part was that this was all at ~ half throttle.  Eventually the starter pinion decided that it was going to break, so we had to go back in.
Title: Aerial Burnout Footage
Post by: taylorp035 on September 09, 2012, 09:40:20 PM
As promised, some aerial footage of the SAE car doing it's burnout from a very stable rc tri-copter using a go-pro camera.


http://youtu.be/tw87eysHiJU (http://youtu.be/tw87eysHiJU)

I hope the youtube function works with this 



Yep... we have too much fun!
Title: Re: Treadmill Dyno
Post by: Frank S on September 10, 2012, 05:06:29 AM
the quality of the video from the tri-copter is amazing. you said very stable , that is almost an understatement
You  have way more torque than traction for sure. nice long straight line burn
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 10, 2012, 07:25:39 PM
The Go-Pro shoots in full 1080p at 30 fps and has that bubble look that I really like for outdoor videos.  The tricopter is good for 8 minutes of flying on a single battery.  I wasn't the person who processed the video, so it might of been post-processed to take out any shaking, but I doubt it.

As for torque... the car only has about 45 lbs on the rear wheel.... work the math backwards and that works out to about 4-5 ft*lbs at the crank to make the wheel spin.  With the larger diameter intake pipe and the high compression head, 5 ft*lbs can easily be achieved at 1/2 throttle.  The video didn't catch the rest of the burnout (it lasted another 20-30 feet).

This Friday we hope to drive the car some more and take better video.  We also hope to get some footage of the entire campus from high above  :)

This was from last winter with the same gear ratio and engine, only with a lot more weight on the rear tire.

Up against my 250 cc 4-wheeler, I would say the supermileage car would beat it to 35 mph (approx top speed of both).  I find this very interesting since the 4-wheel should have a 2:1 advantage on hp/lb and it has a 5 speed transmission.
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 11, 2012, 09:51:32 PM
Here are two screen shots from today from the tri-copter way up in the air looking over the PSB campus  ;D

http://i49.tinypic.com/2hyhq9f.jpg (http://i49.tinypic.com/2hyhq9f.jpg)
(http://i46.tinypic.com/11c4ay0.jpg)



You can see Presque Isle State Park in this one!
 (http://You can see Presque Isle State Park in this one!
http://i49.tinypic.com/5bpydt.jpg)http://i49.tinypic.com/5bpydt.jpg[/url]


(http://i48.tinypic.com/vxnqef.jpg)

The RC truck drove today for 90 minutes on 3300 mah @6s.... that works out to a 2.25 hour battery life for a 10 hp, 10 lb and 4WD truck.  Not bad.....  it reinforces the stuff I learned in Sytem Dynamics class on electric motors and how the current is increased in a squared fashon vs the gear ratio.... last week the truck only had a ~15 min run time.  The main gear ratio was 24:52.  Now it is 15:65, and it still is too fast for the big soft mud tires :)
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 22, 2012, 03:02:36 PM
Now entering the world of miniature spark plugs!  Comparison of the stock plug and the new ones (I know, bad glare..).... we are hoping to go dual spark this year.

(http://i50.tinypic.com/1127mg6.jpg)

Title: Re: Treadmill Dyno
Post by: SparWeb on September 23, 2012, 12:38:46 AM
"Honey, I shrunk the car".
Not into models so I had to google that one.
How long do they last?  Or does it even matter since you don't run the engine 9 miles out of 10?
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 23, 2012, 01:19:03 PM
I'm not sure how long they will last... I'm hoping 50-100 hours, since they were about $20 a piece.  Running at competition will only total about 10 minutes of firing over ~75 miles.



Title: Re: Treadmill Dyno
Post by: Bruce S on September 24, 2012, 09:14:26 AM
Are you going for simultaneous firing over overlap firing?
If course there is also the fun of building a new head for the engine too. ;D
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on September 24, 2012, 07:45:53 PM
I think simultaneous, since the dual plugs will probably be positioned symmetrically inside the head.  The capacitive discharge unit we have is meant for a dual piston, 2-stroke engine for model airplanes.  We also received the rpm readout for it today.

The fun of building a new head is going to be my senior design project  :)   There is also a 2nd smaller displacement engine head in the works too.  I also have a ~900 page book on engine design to read in the near future.

Last Friday we got our EFI engine to run for the first time in ~1.5 years.... unfortunately it has no power, but on the plus side all the sensors seems to be working.  We previously were having a hard time getting the position sensor to work properly.

With the new capacitive discharge unit installed on the EFI engine, total power consumption is only ~1.5 amps at idle and 2.5 amps at ~3k rpm.  Much better than last year's which took about 9 amps with the 1 ohm ballast resistor and about 15 amps with out it.  We hope to run some smaller capacity LiFePO4 cells this year so we don't have to work with the battery management modules.... they caused us to have two fail runs last year.  It would be nice to be able to use a super small LiPo pack for the starter + ignition, but the weight savings just isn't there after you add in the extra electronics.  The LiFePO4 cells will limit us to about 30-40 amps on the starter.... something I hope to modify by buying a ~300 watt outrunner and making a 2nd flywheel that is lighter and safer.  Plus, we need more than 1 flywheel for ~10 engines.

Title: Re: Treadmill Dyno
Post by: taylorp035 on October 04, 2012, 08:51:44 PM
We finally got the clearance to run the CNC router to cut out our new body.  It's going to be a major undertaking.... I'm guessing at least 3 weeks, if not more.  ~60 cross sections, 2" thick and probably cut from both sides for many of the pieces.

In engine land, we properly set up the timing on the ignition system.  We found that we were firing at about 20 degrees after top dead center.... not very good for power  :)  Also explains the extreme surges of power when we were approaching 4k rpm the last time we ran the engine.  Now it runs much better and doesn't guzzle so much gas.  We also modified a stock head to accept two of our mini sparkplugs, so that will need to be tested.

We also received our carbon fiber for our steering, axles and frame.  I think our entire frame will weigh less than 1.5 lbs.  Some teams go with light weight tube frames that weigh 5-10 lbs made of aluminum or steel.  I bet if you used some 3/8" hollow protruded C.F., you could make one for less than 1/2 lb.  We are not going that route due to our extreme lack of space.  Ours will use square tubes that are reinforced by a flat plate and the body, which greatly increases the moment of inertia.

One of the tricky things that we have to think about is how the deflection from the driver sitting in the car will affect the shape of the body.... the frame will probably bend a good 1/2"  :)
Title: Re: Treadmill Dyno
Post by: Frank S on October 04, 2012, 10:25:22 PM
Taylor is there a way you can camber the frame so that the body is stressed then when the driver's weight is added the straightens out and relieving the stress on the body.
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 06, 2012, 04:59:30 PM
Taylor is there a way you can camber the frame so that the body is stressed then when the driver's weight is added the straightens out and relieving the stress on the body.

Well.... yes.  The tubing we bought is straight and the bottom of the car is curved, so there would naturally by a gap between the body and the frame at the center of the car.  So when we actually go to glue everything together, we could manually push the bottom of the car up to meet the frame rails and when the driver sits in it, the shape would be much closer to the original CAD model.  That's a good idea Frank.


Here is a really cool article on Laval University's new car with their research on aerodynamics.  I question a few of their choices and noted the wrong units on the top right graph, but else I'm impressed at the work that went into their design.  I'm definitely jealous of their access to an 8000 processor supercomputer and their large gantry mill for making molds....   

http://www.nxtbook.com/nxtbooks/sae/12MOMD0928/index.php#/6 (http://www.nxtbook.com/nxtbooks/sae/12MOMD0928/index.php#/6)

The part that I really wonder about is that they increased their frontal area by 25% yet decreased their drag coefficient by only 20%.... which should yield higher drag numbers... either I am missing something or they really thought their old car was too small for the driver.   Our new design has a 30% lower drag coefficient and 10 % less frontal area with more room for the driver.
Title: Re: Treadmill Dyno
Post by: DamonHD on October 07, 2012, 11:54:18 AM
You'll have to feed the driver to exactly the optimal weight before starting!  B^>

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: SparWeb on October 07, 2012, 06:46:56 PM
Well, aren't some of the drag forces higher in some of the cases?  That's what I see in the table on the 3rd page of the article.  It seems more like they have "bought" space in the cabin at the "cost" of needing to find design changes to improve efficiency.  The article goes on to show that they have incurred some penalties in cross-winds and turns, depending on the steepness of the turn or the cross-wind, it seems.
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 08, 2012, 11:22:09 PM
Its a very complex problem... obviously it being possible to sway the calculations in your favor... not that I am accusing them of doing so.

Quote
Well, aren't some of the drag forces higher in some of the cases?
Yes.  I'm not sure why the turning drag forces are so high, unless they mean side loading instead.    If they meant the drag forces going around a corner, my calculation figure about a 1.9 degree change between the air hitting the nose and the air at the tail (inverse tangent of 10 ft long car over 300 ft radius).  I highly doubt they modeled that situation.

Based on my simulations so far, the turning force seems like the force perpendicular to the direction of travel for the car.

Quote
It seems more like they have "bought" space in the cabin at the "cost" of needing to find design changes to improve efficiency.

I think you are being kind to me  8)  There are other teams who have done this sideways CFD testing, particualrly the world record holding team.  But I am putting my bets that the wind conditions in southern michigan on a summer day will be fairly tame.  Also, there are trees along most of the track and a concrete barrier on the outsides of the track that should block even more air.  This last year was exceptionally windy...


To make the problem more complicated, the turns are banked.

I think our lower cross sectional area will win the day in the end.  If they are 25% larger, then they must be about .34 m^2.... ours is <.27 m^2 and has in general lower profile airfoils, which have lower drag coefficients.  My current CFD analysis at a 25 deg angle and 15 mph shows a negative drag force  ;D

Also, 25% bigger more means more weight... Laval claimed 94 lbs last year.  We have hopes to hit 70 lbs this year from our 91.4 lbs last year.... which will be quite the achievement considering our limit resources.


(http://i47.tinypic.com/348h64y.png)

http://i46.tinypic.com/2me7arb.png (http://i46.tinypic.com/2me7arb.png)  -  The big version.
Title: Re: Treadmill Dyno
Post by: SparWeb on October 09, 2012, 01:04:14 AM
Banked turns...  Your car is narrower...  Should we be worried?


On another subject, why all this talk about airfoils?  You don't have airfoils...  you have a 3-dimensional body.  There's a quote in the article about the Laval team that said a similar thing.  This sounds like an over-simplification.  I'm all in favour of useful simplifications for the sake or making clear decisions, but this one sounds misleading.  Let me just make my point carefully so that I can reassure myself that I'm not going off half-cocked on the subject:
Looking down on the car body you have illustrated, I can easily tell that the rounded nose, curved sides and tapered tail make it look like the cross-section of a typical airfoil.  At a guess it could be a NACA 0015 or something similar with the greatest thickness at about 30% chord.  This sounds like a rational starting point for selecting the overall shape of the body, following which will come the refinements to fit driver, chassis, wheels, fairings, vents and so on. 
Where there seems to be a problem is when I read statements like "...lower airfoil profiles with lower drag coefficients..."  That raised a flag when I read it in the Laval team article, but I assumed the journalist just won't understand these finer details.  But I'm going to pin you down on this for discussion.
A body like your car's, which is a long slender object, will incur considerable amounts of profile drag, but more than that, it will have parasitic drag due to surface texture and irregularities, fairing interfaces, and varying amounts of induced drag from the vortex shed in cross-wind, such as the one I can see in the graphic above.  Each wheel fairing also sheds a vortex.  Has a sum of all these factors been done that gives you confidence that the profile drag rules them all?
Taking the point further, all the charts you find in books and XFOIL and UIUC are done on 2-dimensional models, which implies zero span-wise flow.  I don't think you can make that assumption.  Not even as a rough starting point.  And the reference area (wing cross-section) is different from frontal area of the car you use.  If you have, in fact, selected an airfoil shape for the planform shape of the car, and have reproduced that shape faithfully around the entire perimeter of the car, then can you model a zero-degree angle of attack case and arrive at the same pressure and velocity distribution published in the book?  It would surprise me if you could.

So maybe I'm not interpreting the direction you take correctly, when making comparisons:  When you model the entire car, and run CFD simulations, do you only refer to the frontal area for Cd or do you also use the cross-sectional area in the horizontal plane, too?

If I had a 3 meter wide wind tunnel I'd love to put your car from last year inside it and try validating all the CFD you did on it!

No kidding you can get lift on the car body in a crosswind.  Short "stubby" wings are excellent for generating lift at very high angles of attack, especially when they are adjacent to walls, which is the ground in your car's case.  On the upper side of a 2D airfoil, the flow would separate at 25 degrees, but on your car the cross-flow can just circulate from windward side to leeward side, thereby reattaching some of the flow to the leeward side of the car.  Stall delayed.  (This just repeats what I was going on about above, I just realized).

The Laval team may speak and work in french (though not necessarily), so the term "Turning force" may be a lost translation of "Lateral force" or it may mean "Drag during turns".  Hard to know for sure which way to take it.  Sounds most reasonable to assume they have tabulated the forces in each of the 3 axes:  One longitudinal drag, one laterally, one vertically.  The effect of the lateral force may cause it to turn, but that may depend on where the centroid of the distributed load is applied...

(sorry... gone on and on haven't I?)  :-[
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 09, 2012, 04:22:20 PM
Quote
(sorry... gone on and on haven't I?)  :-[
  Don't worry, I really enjoy what you guys have to say. 


Quote
When you model the entire car, and run CFD simulations, do you only refer to the frontal area for Cd or do you also use the cross-sectional area in the horizontal plane, too?

I only use frontal area from straight on and then use Drag Force = 1/2 * air density * frontal area* Cd * v^2 to calculate the drag coefficient.

For most of my tests, I modeled the car at 15 mph, with the car in a 250" x 100" tall x 150" wide box.  The incoming air is set at 15 mph and the exiting air is at 0 pressure.  I also set the ground to 15 mph with no vertical or sideways air movement.  The 3 remaining sides are marked as unknown.  Strangely, I am getting a drag coefficient of about 0.17 for my newest designs and about 0.22 for my old car.  I wonder why this is so high???  Maybe the 1/2 is absorbed by the Cd, which then the numbers would make more sense.

The one way that we can check it is by comparing the data from our runs on the track.  Since we know the precise elevation of the track, a starting and ending velocity, and the positions, we can work backwards using an excel iteration to figure out the drag coefficient and rolling resistance coefficient.  The problem is that you end up with an equation like  :  constant = Cd + Crr, where Cd is dependent on Crr.  Since we have an approximate value for both, we can figure out the other, but not exactly.  Michelin claims 0.0024 for Crr for the tires we based this on, so when you put that number in, you get a Cr of 0.14, which sounds about right.  But we have no proof that 0.0024 is correct....   I wish the people who spent all their time testing the radial tires would of published some data on our blue tires.  The radials are claimed to be 0.0008 with no tubes and 5-6 bar.  A Michelin representative once said that the radials have the same Crr with tubes as a blue tire tubeless, which would be 0.0024.  Then he claimed that with tubes in the blue tires, that doubles the Crr...... but there is no information out there to support any of this.
Cd   Crr
0.1   0.0028
0.11   0.0027
0.12   0.0026
0.13   0.0025
0.14   0.0024
0.17   0.0021
0.21   0.0017

Quote
Sounds most reasonable to assume they have tabulated the forces in each of the 3 axes:  One longitudinal drag, one laterally, one vertically.
I think I'm going to have to go with you on this one.  The 3 axis make the most sense.  The weird part is that the 0 degree turning force is not zero.  Unless they designed a car that is not symmetrical....   The track is only 28 % turns by distance.



Quote
If I had a 3 meter wide wind tunnel I'd love to put your car from last year inside it and try validating all the CFD you did on it!

Just this past weekend, I made a 1 / 16th scale model on my mini cnc mill.  It wasn't very good, so I may try again today.  We could make a 1/8 scale model, but it would be 15" long and about 3 " square, which would be a little too big for our wind tunnel at school.  And I don't think we can get the wind speed on the tunnel to 8 times the car velocity (80-160 mph)...... after reading some info about the wind tunnel, it's 24" square and 102 mph max.  Our car would be 1.1% of the area of the wind tunnel, so it would ok in that respect.  The problem is that you have to get the car on the ground too, which might be hard to do in the tunnel.  My CFD tests show that the ground has a major influence on the drag (no ground causes ~ 15% more drag).  I have an A-axis rotary head for my mill, so hopefully my 30 day free trial of my g-code program will make it work.

Quote
Has a sum of all these factors been done that gives you confidence that the profile drag rules them all?

My book on supermileage cars says that skin friction drag represents approximately10% and  profile drag is 90%.   We did try and add a giant shark fin down the back of the car and it upped the drag by ~40%   ;D


Title: Re: Treadmill Dyno
Post by: Frank S on October 10, 2012, 04:25:10 AM
Taylor you might try to play around a bit with the profile surface texture and the textures where there are abutments in the curvature like the cowling extensions in front of the wheels.
 Think of the dimples on a golf ball. these create super micro turbulence eddy's. These eddy's in turn reduce the cf allowing the golf ball to travel further than a smooth ball of the same size & weight. when it comes to micro eddy's size matters too small and the turbulence will not be sufficient to reduce the resistance of flow, too large and they will increase the drag. 
 I learned a little about this from a guy who used to race sail boats both in fresh & saltwater. the 2 having different densities he would vary the way he applied his bottom fouling paint depending on if he was going to compete in fresh or saltwater. he found that an absolute ultra smooth polished and or waxed surface could actually slow his craft over that of having a brushed on slightly roughened texture to his paint. water being 800 times as dense as air it got me to thinking about why golf balls have dimples. I had always thought it was to help cause spin and directional control. this started me to thinking about the football as well a leather football has texture to its surface and will travel further than a slick plastic one of the exact same weight
 Something to think about as long as you are in the modeling stage 
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 10, 2012, 08:48:53 PM
That's another good point.  My teacher who teaches aerodynamics and fluids at my school is big into sailboat racing and I bet he has something to say about this.  I'm not sure how this would apply to air instead of water though..... I wonder if any of the F1 race cars have anything like this....

Since there is the factor of 800, I wonder if the threshold for the perfect surface finish would actually be 800 times less rough or something like that.  Maybe 10 times.  I have yet to see any team mention this idea.  It would probably only apply up to the widest point on the car, where the velocity gradient stays very high. 
Title: Re: Treadmill Dyno
Post by: SparWeb on October 11, 2012, 12:43:47 AM
When you're just guessing, you look at golf balls,
When you're learning, look it up in Anderson,
But if you want Understanding, you need Hoerner.

Try this first:  http://www.amazon.ca/Introduction-Flight-John-Anderson/dp/0073380245/ref=dp_ob_title_bk

(Kind of like "aerodynamics for dummies" except these dummies already know algebra and calculus.  Maybe you already have something like it such as Skip Smith or Blevins.)


Then get this:  http://www.darcorp.com/books/Drag/

You will find the test data on land vehicles to be very interesting.  But you will also get a lot from the early chapters.

On the subject that Frank brought up, you want to look for all parts on "boundary layers".  You can get some guesswork started on vortex generators, if you want to try, however it's still not a science that can predict results, it just helps you weigh choices.

One last note, if I can convince you to buy a copy of Fluid Dynamic Drag, I'd like to recommend that you contact Mr. Hoerner's widow to buy it from her directly.  It sounds funny now, but 20 years ago, before the internet, she maintained the stock of self-published books very diligently, and by word of mouth many aeronautical engineers bought the book(s), which made a tidy retirement income for her.  I think she continues to do so to this day.  Sure you can get it through DARcorp, but I doubt Liselotte gets the same value.  I have all the contact info still pasted into the back page of my copy.
Title: Re: Treadmill Dyno
Post by: Frank S on October 11, 2012, 06:53:09 AM
Spar web I can't remember how many years it has been since I've heard those names.
 wasn't there a chapter or a paper that Hoerner published on wing tips design? I know that canard is the popular name associated with them.
Memory is the one tool that sadly wanes over the years It comes and goes in spurts Like  something I red OH! SO! many years ago pertaining to the reason a Peregrine Falcon could dive at a higher velocity than what was considered terminal for a mass of its weight and why  the oils in the feathers of a goose allowed it to soar effortlessly for miles or that of the albatross whose long flights consumed less energy than what was thought to be reasonably possible.
 Or why a polished bowling ball could be made to curve at the exact moment the bowler desired but one that was not polished would not. while the unpolished ball would deliver a higher strike force that the polished one. This may have been due to its rolling instead of spinning The cobwebs of time are taking over in that area
 In one of the chapters in MR Hoerner's book I think remember he contradicted himself but not entirely there are times when things should be smooth as a polished mirror then there are times when a patterned texture shows a lower resistance 
Title: Re: Treadmill Dyno
Post by: SparWeb on October 11, 2012, 02:56:28 PM
Yea fluid dynamics doesn't go out of date, so dog-eared copies of these books are still found on engineers' shelves.  Then again the land vehicle section of Hoerner covers tests from the 50's and 60's so you can just guess what those cars look like.
FYI a "canard" is only used to mean the stabilizer surface placed ahead of the main wing (opposite to a horizontal tail stabilizer, behind the wing)
And a "winglet" is a small aerofoil that projects at roughly right-angles from a main wing surface.
Winglets are not magic, and they can serve many purposes.  They do not magically improve fuel efficiency or glide ratio just because you bolt some on.
Neither winglets nor canards are relevant to a supermileage vehicle, certainly not to Taylor's current design.

Air is viscous, and drag is related to both the displacement of the flow (profile drag) and the gradient of flow speed at the surface of the vehicle.
I realize now that I've thought about it, a 15 MPH supermileage car will not build up a significant boundary layer so playing around with the laminar/turbulent transition point will not gain much at all.
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 11, 2012, 04:07:29 PM
Some more pcitures:  This is the wheel skirts, about halfway up.

(http://i45.tinypic.com/4vo6kj.png)
Larger version:
http://i49.tinypic.com/30wo3n4.png (http://i49.tinypic.com/30wo3n4.png)


Rear wheel skirt, down the center, with a high mesh density on the bottom ~3".  We plan on making the leading edge a bit more rounded.
(http://i49.tinypic.com/6gl7h0.png)
Larger Version
http://i50.tinypic.com/14e4ef8.png (http://i50.tinypic.com/14e4ef8.png)
Title: Re: Treadmill Dyno
Post by: Frank S on October 11, 2012, 06:50:14 PM
 I still have my  old Smoleys book of combined tables I doubt if I have opened it since the days of slide rules though. I used to keep many of my old books at my office at work but after several started to come up missing I no longer keep them there I only hope that the young engineer wannabes who took them will someday understand their value and what the scribbled notes on the onion skin papers I had inserted in so many places stood for.
Title: Re: Treadmill Dyno
Post by: SparWeb on October 11, 2012, 10:12:46 PM
Your wheel fairings are symmetrical airfoils.
If the front pair of wheels had cambered airfoils, with "top" curvature facing outward, there would be less velocity gradient underneath the car.  Think of the space under the car as if it were a duct, and you'll see.
Unless you want the downward suction...  Maybe it's not large enough to matter (your CFD from last month's screen-shot shows virtually no net force, vertically).
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 13, 2012, 09:24:24 AM
I agree Sparweb that we could design the wheel skirts as to lower the air speed under the car, but the down side is that currently the pressure below the car and above the car is just about perfect....   In our earlier iterations, there was too little pressure on top and too much on the bottom, which was causing air to ride up the sides of the car in the last ~ 3 feet near the tail.

I question if an air foil like you suggest  would have increased drag over the design I have now.  If the aerodynamics were my senior design project and  I could spend 500 hours on it, then maybe I could look into this fun stuff.  But for now, I think we have achieved a fairly good result.  Of course, all of this is much harder to do since it's a 3-D problem.


Last night, we cut the first 3 sections of our foam mold.  The initial coding of the g-code was not very good, so it took a long time to cut out each piece.  It also didn't help that our cnc router was only doing ~30 IPM average and maxed out at 60 IPM..... the router cuts the circles with small line segments, which it not very fast, so we are going to lessen the tolerance on the g-code so the lines are longer and therefore the machine will run faster.  We also figured out how to program it so it cuts like an apple peeler.... it spirals from the top of the piece to the bottom in one continuous cut.

We also stiffened our starter motor mount since we vaporized another starter pinion last night during our on campus car show.  It was too bad, because we had the chance to drag race a v-8 powered lawnmower  (~85 hp). 

Title: Re: Treadmill Dyno
Post by: SparWeb on October 13, 2012, 07:39:46 PM
Quote
...we had the chance to drag race a v-8 powered lawnmower
LOL!

Quote
...But for now, I think we have achieved a fairly good result.  ..

I was just being nit-picky on details before.  I think you've achieved an EXCELLENT result!
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 14, 2012, 02:22:34 PM
Quote
I was just being nit-picky on details before.  I think you've achieved an EXCELLENT result!

It's going to take an excellent result to break the north american mpg record (3169).  Personally, I think 5000-6000 mpg is doable if everything were to go right.  The europeans have proven this to be true with 6000-8000 mpg cars with slightly different rules (mainly a lighter driver, less visibility, easier brake test,....).
Title: Re: Treadmill Dyno Pink Foam Edition
Post by: taylorp035 on October 21, 2012, 04:56:40 PM
Progress!!!


(http://i47.tinypic.com/10n9e89.jpg)

(http://i49.tinypic.com/2q21q1s.jpg)


We should be able to get another sizable chunk cut for this week, since we are getting better at running the cnc machine and each layer has less to cut (.050" x-y step size with variable z height).

Also, we received our new starter motor, super light weight ESC and new batteries.  I think the motor is ~ 2-3 times lighter than what the euro teams use on their tiny engines (I guess my experience in 15 lb combat robots will finally pay off  ;D  ).
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 28, 2012, 08:20:01 PM
A moderate amount of foam was cut this week.  We are now up to the 30" mark.  We did rough cut all the foam so it is ready to be thrown into the machine.

Else, the mini starter motor was mounted, tested and broken   :-\.   The custom shaft we made for the motor bent.  It lasted for about 30 seconds worth of cranking the engine.  So now we are making a new shaft out of a 1/2" socket head cap screw.  The original piece of steel probably didn't have a very high yield strength.  The small diameter is 5 mm and the largest is 1/2" and about 3" long.  The flat spots are for the Briggs bendix.

(http://i49.tinypic.com/311xg2e.jpg)


While it was cranking over, we were able to get the 4s 65C 1300 mah Lipos toasty, which is a first.  Tomorrow, I hope to put a doc wattson meter inline to see how much power the 400 W motor is really pulling.  We will also probably program the ESC for maximum starting power and specify a 14 pole out-runner.

Here is the motor assembled

(http://i45.tinypic.com/j5e5c5.jpg)
Title: Re: Treadmill Dyno
Post by: SparWeb on October 29, 2012, 02:44:44 PM
Else, the mini starter motor was mounted, tested and broken   :-\.   

And the warranty was voided.
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 30, 2012, 08:01:55 AM
With the new shaft and the doc wattson inline, it peaked at 115 amps and 1400 W   ;D  But the tiny set screws connecting the bell of the motor to the shaft couldn't handle the torque and failed.  I guess the next thing to do is put a pin through the shaft and the bell housing.  I'm really impressed by the speed controller at this point, since it's only rated for 50A continuous, but I guess that's what you get when you buy nice American made products  :)

Title: Re: Treadmill Dyno Pink Foam Edition Week 4
Post by: taylorp035 on November 03, 2012, 06:35:18 PM
We had about 8 hours on the CNC machine yesterday so lots got cut.  I think we cut 22 cross sections in that time.

(http://i50.tinypic.com/ogjuax.jpg)

(http://i47.tinypic.com/zoi6ft.jpg)

Later on, we discovered that our foam board adhesive wasn't drying (~3 hours after applying it).  We then read the label and it said not to use on 'non porous' surfaces.... which the foam is closed cell and there is no plywood as there normally would be.  Hopefully 48 hours will let the stuff dry.  Next week we hope to start applying drywall compound on the front pieces since it will take ~100+ man-hours to make it perfectly smooth to our satisfaction.


The mini starter motor was yet again reinforced, but after running it too often/long, we let out some of the factory smoke.  It was probably just some of the insulation burning off the coils.  The magnet bell wasn't too hot.   Also, setting the ESC to a 80A max wasn't getting the job done, so we removed the current limiting.  Peak power was recorded at 1000W.
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 06, 2012, 08:27:23 PM
After letting the foam board adhesive sit for ~72 hours, it hasn't dried one bit   :(   So today, we bought some construction adhesive, which the label looks like it will be good for non-porous surfaces and foam.  Does anyone have experience with this?  We are going to try it out tomorrow and if all goes well, it will be applied to all ~35 cross sections on Thursday and be dry by Friday, which then we can start adding drywall compound.

(http://i48.tinypic.com/27wrwb7.jpg)

Title: Re: Treadmill Dyno
Post by: SparWeb on November 07, 2012, 03:12:20 PM
Some types of construction adhesive do get used for bonding insulating foam to walls, so you are okay there.  Gotta pick the right one though:

IS             http://lepageproducts.com/ProductDetail.aspx?pid=72

ISN'T        http://lepageproducts.com/ProductDetail.aspx?pid=77

It's also very viscous, IIRC so applying just enough to keep the bond-line thin will be tough.  Or you can let the car get 10% longer...

Title: Re: Treadmill Dyno
Post by: taylorp035 on November 07, 2012, 05:40:05 PM
Today we looked at the glue we used before and saw that it was not recommended for foam to foam applications.... too bad we didn't read that earlier.  The new stuff we got is almost dry after ~4 hours, so things are looking good.  The downside is now we can't seem to separate the foam mold anymore... so maybe the glue dried???  If it stays stuck together, I don't really care what happens.


Title: Re: Treadmill Dyno
Post by: taylorp035 on November 10, 2012, 12:28:55 PM
The body is finally done being cut out  :D   I think the total cutting time was about 20 hours on the cnc router.

(http://i47.tinypic.com/2r26tll.jpg)

(http://i46.tinypic.com/2m3ny1t.jpg)


Gluing the whole thing in the vertical position was a challenge since the aluminum bars in the center were 12' total in length.... we eventually tied the car to the ceiling to make sure it wasn't going to fall over.

Work was also done to measure the pressure drop over the intake and exhaust valves using a vacuum cleaner, an air flow rate meter and a pressure gauge.

Title: Re: Treadmill Dyno
Post by: taylorp035 on November 14, 2012, 10:02:12 PM
We found that our second type of glue (the construction adhesive) isn't drying either..... so when we went to put the car in the horizontal position, it broke in 3 places  :/   But after a quick test today, we found that hot glue works really, really well, so it looks like we have finally solved our problem.

This Friday, I will put my windmill blade carving skills to the test by doing the front side of the rear wheel skirt.  We decided to keep the edges of the bottoms of the wheel skirts "sharp" instead of rounded over, because we think the airflow will be better.  Some teams have edges that are very sloped, which we think would push air down towards the ground instead of neatly around the wheel skirt.  The world leading supermileage cars all seem to have a different answer to the shape of the bottom of the wheel skirts.  Even the multi-million dollar solar cars have different designs, some have rounded edges and others have sharp edges... and many of those cars spend some serious time in the wind tunnel (oh what I wish I could do with our car mould, some modeling clay and about a whole day in a giant wind tunnel   ;)  )
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 17, 2012, 08:09:37 PM
Progress:  Pink mold is now covered in drywall compound.

(http://i46.tinypic.com/169p4xz.jpg)


Trying to give the shape of the car justice with a camera is near impossible... it really takes a minimum of a minute and a walk around the car to absorb the whole thing.  You really start to appreciate the preciseness of a cnc machine in the ability to make the curves perfect..... especially after building last year's car by carving the whole thing by hand.

 
Title: Re: Treadmill Dyno
Post by: Frank S on November 18, 2012, 04:19:31 AM
It looks like it is almost time for the fun to start with all of the hours of meticulous hand sanding before you make the outer mold. it would be nice if you could lay your hands on a portable coordinate measuring machine  like this
[attach=1]
Title: Re: Treadmill Dyno
Post by: DamonHD on November 18, 2012, 04:51:22 AM
Ha!  At least one person here who shall be nameless (OK then, Ghurd), already KNOWS that hot glue is the solution to all the world's structural problems, and probably financial and energy problems too if we could just work out how to do it right!  B^>

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 18, 2012, 09:50:49 AM
Quote
it would be nice if you could lay your hands on a portable coordinate measuring machine  like this

We do have one of those, but it's probably only good for a ~15" radius working envelope.  There are other ways to get the mold back into a digital format, including some newer software that takes pictures and meshes them together to make a 3D model.

Ha!  At least one person here who shall be nameless (OK then, Ghurd), already KNOWS that hot glue is the solution to all the world's structural problems, and probably financial and energy problems too if we could just work out how to do it right!  B^>

Rgds

Damon

My adviser feels the same way about hot glue.   We even bought different grade of hot glue sticks, including some high strength stuff, that actually does seem to be stronger.
Title: Re: Treadmill Dyno
Post by: ghurd on November 18, 2012, 09:11:25 PM
My adviser feels the same way about hot glue.   We even bought different grade of hot glue sticks, including some high strength stuff, that actually does seem to be stronger.

I am not trying to be an X-Purt on the stuff I love...

but usually,
Hi Temp 'sticks' better to normal, and strange, stuff.
Lo Temp might be a little faster to work with, but that is the only advantage I see.
Multi Temp is fine, but only after the gun is 5 minutes past completely heated up, and IMHO it works best with a hi temp gun.

I feel the biggest difference is in the gun itself.
If you can see daylight through, from the stick spot to the hot spot, then forget it.

And you get what you pay for.
No more 99-cent or $2.99 guns for me.  Those seemingly over-priced mini-guns are worth it for someone serious.

Last few years I have been using the 5/16" Ad Tech Project Pro (with the needle tip instead of a funnel tip), and hi or multi temp sticks from wally.

Even 35 years ago, higher end cabnitry was assembled with hot glue.
G-
Title: Re: Treadmill Dyno
Post by: taylorp035 on November 25, 2012, 09:49:07 PM
We got word today that we will be able to obtain some of the coveted radial tubeless tires that we have been trying so hard to get for the last 3+ years.  In theory, these tires could reduce the rolling resistance of our car by a factor of 3, which is super important if we want to break the North American record  :)

Now for some more CFD.   I was able to set up the model with hollow wheel skirts and a spinning tire in one of the front side skirts and the other empty.  I was interested to see roughly just how fast the air is actually moving inside and maybe what we could do to make it better.  The analysis was pretty intensive (transient with motion and a high mesh density), which is now possible with my black friday purchase of  8gb of ram for my thinkpad w500 laptop.  It took me about 3 hours to get the whole thing setup and drawn the way I wanted it.

The first one is the one without the tire and an opening in the bottom of the skirt.
Full size:    http://i45.tinypic.com/25gw75z.png (http://i45.tinypic.com/25gw75z.png)
(http://i45.tinypic.com/m5zdk.png)


The second one has the tire.  It's not very good, since there seems to be a massive leak  in the bottom of the skirt.... probably due to the mesh not recognizing the thin parts.

Full size :   http://i49.tinypic.com/349cwa8.png (http://i49.tinypic.com/349cwa8.png)
(http://i49.tinypic.com/308fp1h.png)
(http://i50.tinypic.com/120giew.png)


Also note the lack of the tire touching the ground.... I have yet to solve this issue, so for now the model can only get to within ~1" of the ground.  The block-ish shape to the inside of the car is a result of not being able to make a shell out of my cad model... so I had to extrude the volume out.  It should be close enough to get the general idea.


Some inspiration for my CFD work from the world of solar car aerodynamics:
http://www.nuonsolarteam.nl/nieuws/inside-the-wheel-cover/?lang=en (http://www.nuonsolarteam.nl/nieuws/inside-the-wheel-cover/?lang=en)

It's too bad they don't actually show more of their results/conclusion other than an effort to minimize the air gap between the wheel and the skirt.  This is something we have a solution for that we hope to implement on the new car.
Title: Re: Treadmill Dyno
Post by: Frank S on November 26, 2012, 05:36:20 AM
Taylor could your have used a revolve to cut feature to remove the interior volume? by creating a geometric plane 90 deg to the axis
Title: Re: Treadmill Dyno
Post by: SparWeb on November 26, 2012, 03:03:13 PM
I fear the 3D profile will have a lot to say about what happens in the wheel-well, not just a 2D profile.
Flow through spokes, (or is it on a solid disk) brake disks and calipers, that sort of stuff.
Not saying it isn't important - I'm worried about the amount of work needed to get a useful result.

Those sacrificial skirts (in your linked article) look like a funny thing to try, though.  You would rather have the main skirt come down as close to the ground as you dare.  Maybe a lower 1/2" of paper/foam/nomex that will scrape off during trials runs, leaving whatever maximum material condition can exist without scraping any more.

Title: Re: Treadmill Dyno
Post by: taylorp035 on November 26, 2012, 09:51:03 PM
Taylor could your have used a revolve to cut feature to remove the interior volume? by creating a geometric plane 90 deg to the axis

That would of been a smarter idea for sure.... at least for the top part.  The bottom still needed to be flat to represent the actual shape.

Quote
I fear the 3D profile will have a lot to say about what happens in the wheel-well, not just a 2D profile.
Flow through spokes, (or is it on a solid disk) brake disks and calipers, that sort of stuff.
Not saying it isn't important - I'm worried about the amount of work needed to get a useful result.

The question is "what is useful?"....  getting a drag force isn't really on top of my list... especially since I can't set the car up properly and my original drag numbers from a month ago are all about a factor of 2 too high....      And yes, 2D airflows really don't serve the problem justice..... time to start wishing for a 3D hologram monitor for my laptop  ;D

Quote
Those sacrificial skirts (in your linked article) look like a funny thing to try, though.  You would rather have the main skirt come down as close to the ground as you dare.
I agree that their solution is not what we really want/need.  Our wheel skirt is only 1/2" - 1" off the ground, depending on the tire used, inflation pressure and how much the frame decides to bend..... you can't really go any lower than 1", especially since the skirts are so long.... I can't count the number of times the car beached itself on a bump in the road/sidewalk.  We have an idea where you take their secondary mini skirt frame idea/location and then take some stretchy material and cover the gap between it and the main skirt.  This is something I have never seen before used on a SMV car or solar car, and I hope to prototype it in the coming weeks.  The hard part is rigidly attaching the 2nd skirt/frame to the axle, which is made of carbon fiber and there is literally no clearance room for it.


EDIT:

Airflow picture near the nose.  Looks like we did a fine job at getting the nose at the right height.

http://i47.tinypic.com/1zn39mw.png (http://i47.tinypic.com/1zn39mw.png)
(http://i46.tinypic.com/10nsuol.png)


Title: Re: Treadmill Dyno
Post by: Frank S on November 27, 2012, 07:08:00 AM
Quote
I fear the 3D profile will have a lot to say about what happens in the wheel-well, not just a 2D profile.
Flow through spokes, (or is it on a solid disk) brake disks and calipers, that sort of stuff.
Not saying it isn't important - I'm worried about the amount of work needed to get a useful result.
The question is "what is useful?"....  getting a drag force isn't really on top of my list... especially since I can't set the car up properly and my original drag numbers from a month ago are all about a factor of 2 too high....      And yes, 2D airflows really don't serve the problem justice..... time to start wishing for a 3D hologram monitor for my laptop  ;D

[/quote]

Don't we all dream for a set up like the one in the ironman movies LOL to include the robot helper
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 01, 2012, 07:19:40 PM
Some engine testing of the high compression head at ~1300 rpm.
http://youtu.be/9osDzvURCIk (http://youtu.be/9osDzvURCIk)

Note the "Chill BRAH!" sign.... it has nothing to do with the fire alarm, but more of a reminder not to rev the engine to 6k rpm.... later on, we decided to build a blast shield on the front of the dyno stand to protect us in the event of a failure.

The bottom was dry-walled last night.  It took 8 or so people a good 2+ hours to apply the compound.  We should be on track for having it done by next Friday and then we can prepare for doing carbon fiber the next week.

(http://i46.tinypic.com/21aa100.jpg)


Title: Re: Treadmill Dyno
Post by: zap on December 09, 2012, 12:53:39 AM
Cool... it almost looks like an orca on it's back!  Nature always knows best.
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 09, 2012, 01:58:07 PM
Finished the new flywheel!   It has a timing pulley cut into the center hub, along with the tapered hole and key slot.  The cross bar has the fancy engraved letters and has been polished for several hours with metal polish and clear coated to prevent any corrosion.  The new flywheel cuts about .35 lbs from the cross bar while only slightly lowering the moment of inertia.

(http://i49.tinypic.com/35apqn7.jpg)

(http://i47.tinypic.com/4rq1xi.jpg)


A nice shot with last year's car in the background.  We are estimating a 40% reduction in air drag for the new car, even though the cars look rather alike.  Initial measurements shows the new car being about 2.5" narrower  The first round of carbon fiber should be applied next Friday.

(http://i49.tinypic.com/10x98vr.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 16, 2012, 04:24:58 PM
(http://i45.tinypic.com/2zq8ocm.jpg)

We went fairly conservative on the carbon this time around.  Many areas are only there for aerodynamic purposes (actually, nothing will be structural).  Over the whole night, we had about 24 people show up, and in total, it took about 60 man-hours to get the car from it's drywall state to getting vacuum pumps running.  It took about 1.5 hours with ~12 people to lay and glue the carbon fiber on.   In a few weeks, we will do the bottom half, which will be significantly more difficult.

(http://i47.tinypic.com/293y51w.jpg)

If you are interested in some photos of the wet layup, I have those too.
Title: Re: Treadmill Dyno
Post by: SparWeb on December 16, 2012, 11:59:21 PM
I get the picture, but then I've vacuum bagged CF before.  Had an autoclave to play with too, heehee.

The bottom will definitely be tricky, so I would like to see how you manage that.  Does it have to be carbon fibre?  Why not glass, which is often easier to drape?  May also be easier to work the resin into glass cloth than cf? 

I sort-of recall that bagging can be done with multiple pieces - hard to describe in words.  It looks like you did the body today with just one big bag, which would have left a lot of empty space underneath between the front wheel fairings.  I think I can see that in the photo.  The key is the way to bag around the mold, because areas where the bag "tents" over a corner will not be compressed, so I think the trick is to assemble a bag with many sections...  Literally cut the bag, letting a long free edge hang, then stick on the next piece to the free edge, which will wrap onto the next side.  Like, one for every major face, with lots of free edge.  Join the edges with putty.  Slowly apply the vacuum, and if it becomes obvious that the bag doesn't fit, don't proceed, rather rip off the bag and put in a new section with slack where it tented up before.  Be prepared with the materials ready just in case.

It was all pretty thoroughly planned in advance when I did those projects (long ago!).  I think you'll be improvising as you go with the one-off project, and from what I've seen so far, it will go swimmingly.
Title: Re: Treadmill Dyno Carbon Fiber pics
Post by: taylorp035 on December 17, 2012, 04:02:20 PM
Well, we took off the vacuum bag today and unfortunately, it seems like we have the same exactly problem as last year, only a little bit better.  Now were are close to 100% certain that the wrinkles are caused by the vacuum bag it's self (exact same pattern as the vacuum bag).  So we have decided that this top layer is going to be thrown out and we will re-surface the mold.  Then, we plan on doing a wet layup with no vacuum bag, since we know that will work.  We also noted that we were very close to the minimum amount of glue needed to get all of the fibers wet (the vacuum pulled it all out).  Total weight felt like about 3-4 lbs, so not too bad.

There are even micro wrinkles in between the large wrinkles that you can see with the camera.  The inside surface was better, but there were valleys where the wrinkles were.

Larger Version:  http://i45.tinypic.com/21alpgy.jpg (http://i45.tinypic.com/21alpgy.jpg)
(http://i48.tinypic.com/kaqqro.jpg)

(http://i46.tinypic.com/2w7064h.jpg)
Title: Re: Treadmill Dyno
Post by: SparWeb on December 18, 2012, 12:04:16 AM
Oh, no!  I suppose the inside is silky smooth instead...

Where did you apply the vacuum?  I have a few thoughts about what may have happened... but just guessing until I can think about it a bit.

I didn't look at this critically before, but maybe I can help you compare the layup stack you used with the recommended practices that tend to get better results.  I've got several composites books stashed away in PDF on this hard drive.  Getting a "male" part surface to look nice from a male mold is not the easiest thing to do.

A cold wet-layup with no vacuum will be heavier, and ultimately even more work than a bagged mold (done correctly) because you will be sanding sanding sanding anyway.
Title: Re: Treadmill Dyno
Post by: Frank S on December 18, 2012, 07:51:56 AM
  Could you now take this shell before removing from the mold and ad some support ribbing and framework.
 then use it as an outer female mold the inside of it should be smooth if not add some fill and sand until the desired smoothness is achieved. Laying up a male part in a female mold is 100s of times easier plus it allows for the addition if internal ribs or supports as needed. Much easier to make a second or 3rd body shell if needed.
 Or before attempting to make another male part on your male mold get some white shrink wrap like they use to wrap boats and escalators for shipment bag your bare male mold then heat shrink until the desired smoothness is achieved with some vacuum to create a glove. slit open the glove along a non critical area remove, then lay up your fiber & resin then slip the glove over this the plastic will have enough stretch to pull over the product seal the seam and apply your vacuum again this time your glove already has the basic contours as a start point and should offer much better results.
 I personally like to use a female mold to make a male part whenever possible
 Just a thought 
Title: Re: Treadmill Dyno
Post by: Frank S on December 18, 2012, 07:55:25 AM
by using the existing shell that you have you can also spray you gel coat or color coat in the mold before applying the resin & fiber. 
Title: Re: Treadmill Dyno
Post by: taylorp035 on December 18, 2012, 12:39:33 PM
The top part of the mold is completely un-usable at this point... dimensionally, it is stretched out and could never be used as a female mold.  We really need the carbon to be the exact shape of the mold, else the tires and engine will not fit.  To put this into perspective, you can see the picture below for how we got the carbon off... this was after 2 hours of trying to peel it off.

(http://i49.tinypic.com/2n6er1l.jpg)


Quote
Where did you apply the vacuum?

On the bottom side of the the front right wheel fairing where there was no carbon.


Quote
A cold wet-layup with no vacuum will be heavier, and ultimately even more work than a bagged mold (done correctly) because you will be sanding sanding sanding anyway.

Right, the layers won't be very compacted, but we can use rollers and squeegees to make it half way decent.  We aren't too worried about the sanding..... if there are no wrinkles, sanding is actually quite easy.


Quote
Or before attempting to make another male part on your male mold get some white shrink wrap like they use to wrap boats and escalators for shipment bag your bare male mold then heat shrink until the desired smoothness is achieved

Yes, we have thought of this and would of done this.  Our theory for the wrinkles last year was that the glued was too dry before we pulled a vacuum... but it turns out that was not the case.  I think any future cars would have a female mold made and have a gel-coat surface for sure.  The hard part of a female mold is how to cut the sharp end of the wheels skirts and tail.  I guess you could add them in later if you wanted to.  Also, a female mold requires a lot more foam and depending how you make it, a bigger CNC machine.  This is definitely something that could be improved upon in the future (many local companies have this capability).  The gain might only be 5 lbs over our current method, but it might be worth it.  More use of a carbon fiber tube frame for the engine mounts and main support structure could yield another pound or two.  Then even rebuilding the engine block to make it lighter (carbon fiber bottom end, smaller and lighter crank shaft...) is another option.  Time, money and creativity.... luckily we have at least a medium amount of each to work with this year.
Title: Re: Treadmill Dyno
Post by: Frank S on December 18, 2012, 01:44:10 PM
I may be looking at it from the wrong perspective. But consider this just as a penny farthings worth of thought
 You already have your master for a female mold
1/4 it end to end along girth at the widest point the  make the second slice end to end vertically straight down the center. Calculate the desired body outer dimensions. take the 2 top 1/4 pieces and place a thickness shim between them coat with a release agent then spray on a mold gel coat, now lay up several layers of fiberglass over this adding a  enough struts of wood to make a sturdy frame  glass them to the mold body.
 do this for the bottom 1/4 just as the top
 afterwards remove the shims and maybe have to cut some of the foam core to allow the master blanks to be removed.
 Now yo would have a top and bottom female mold  the 4 1/4 pieces become your Male cores without using the shims you now apply your release agent spray the gel coat lay in and roll the resin & carbon then insert the 1/4 mold male pieces wedge tightly then pull your vacuum the end result hopefully if you did everything correctly will be your 1 to 3 layer thick carbon body shell in an upper and a lower easily joined together
 It is possible the lower male master may have to be cut into as many as 4 pieces and shimmed accordingly
 If you can find a book or a video on how a Boston Whaler boat is constructed they are the absolute Gods of fiber-glassing  second wold be glass craft 
 A short step to this would be to forgo using the 1/4 molds in the final molding process and just vacuum press it like you did for the outer
 Like I said just a penny farthings worth
Title: Re: Treadmill Dyno
Post by: Frank S on December 18, 2012, 02:02:38 PM
And no I was not referring the the high wheel bicycle in this case I and using it as a half cent LOL
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 02, 2013, 11:56:00 PM
For anyone who has been following my car on a closer level for a decent amount of time and a posting I made in the pub a few weeks ago, you will really like my latest CFD video(s).  You can look on my youtube channel to see the other videos.
http://youtu.be/fudI8lNxCZE (http://youtu.be/fudI8lNxCZE)

And the supermileage Christmas presents arrived.  We now have a set of the radial tubeless tires that will greatly reduce our rolling resistance.  It has taken me ~3 years to get these and are absolutely priceless to us.  We are very grateful for the team who let us purchase them.
(http://i45.tinypic.com/343t24k.jpg)
(http://i49.tinypic.com/143q5ck.jpg)
(http://i46.tinypic.com/2v2uob6.jpg)

Edit:     I wonder what kind of performance gains could be made if these tires utilized carbon fiber for all the strands.  It might be pointless, since super high inflation pressures mean that even an 1/8" rock can cause a blow out.  Anything above ~80 psi starts to cause issues..... but anything goes in a supermileage competition when trying to break records :).  Maybe if a super flat and smooth polished concrete surface that is over a mile long could be found.... maybe a space shuttle landing strip?

Title: Re: Treadmill Dyno
Post by: SparWeb on January 03, 2013, 02:39:00 PM
Your channel has more views than some episodes of Top Gear (which are getting suggested by Youtube in the right-hand bar now).  Congrats!

Something about CF in a tire doesn't sound right...  can't put my finger on it.

How about some of the AFB's in your area for a nice long straight runway?  (a little closer to you than Edwards AFB)
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 03, 2013, 09:07:51 PM
Quote
Your channel has more views than some episodes of Top Gear (which are getting suggested by Youtube in the right-hand bar now).  Congrats!
Thanks!  I have over 200 videos of all the fun things I do, so I guess the total should be fairly large.  My most viewed video is one right after we port and polished the intake on a stock briggs engine.

Quote
How about some of the AFB's in your area for a nice long straight runway?
  We were thinking Presque Isle State Park, which is concrete and 13 miles around with a speed limit of 25 mph....  It would require some special arrangements.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 20, 2013, 11:19:19 AM
Attempt #2 of doing to top carbon fiber.  This time there was no vacuum bag.  We also used a twill weave on the visible layers, so it draped over the mold much better and we were able to eliminate all of the relief cuts.  A slight modification to the location of the middle layer was done after inspecting the stiffness of the first attempt.

(http://i49.tinypic.com/709vn8.jpg)
Title: Re: Treadmill Dyno
Post by: DamonHD on January 20, 2013, 02:17:48 PM
I like the high-tech cellulose-based multi-legged temporary support structures (ie wooden stools)!

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 20, 2013, 06:03:32 PM
I like the high-tech cellulose-based multi-legged temporary support structures (ie wooden stools)!

Rgds

Damon
LOL!

They also make handy portable workbenches.... if you run out of space to put your tools down, just grab another stool.  At one point, we had 6 stools surrounding the car with various tools, including 5 sets of allen wrenches and 3 sets of socket wrenches... that was a nightmare trying to find our single 9/64" allen key, which most of the socket head cap screws in the car used.

The stools also come in handy since we technically don't own the table in the middle of the room, so permanently putting the car on it would result in that much more space that we don't really have.
Title: Re: Treadmill Dyno
Post by: Frank S on January 21, 2013, 03:36:20 AM
 Your top shell is looking good, but! and I'm not trying to be too critical but wouldn't a drop sheet of some sort on the floor have been a good idea? I think can see an outline of resin on the floor all around the model, that stuff is hard to get up. About the only way I have found was after it is dry is to grind it.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 21, 2013, 03:40:11 PM
Your top shell is looking good, but! and I'm not trying to be too critical but wouldn't a drop sheet of some sort on the floor have been a good idea? I think can see an outline of resin on the floor all around the model, that stuff is hard to get up. About the only way I have found was after it is dry is to grind it.
Yep....  I used a hammer and a chisel to get the carbon strands that were glued last time.  Last year, we put down a 12'x10' sheet of plastic, but all of the glue just migrated to the edge of the sheet, so there is now a clear outline of the sheet on the floor.   It also made it extremely slippery (wet glue on plastic) and people fell down multiple times.  A DA sander with 60 grit should take care of anything left over.... but we will hold off on that until we are done with the carbon.  After the body is done, we have to glue in the frame rails, roll hoop, steering assembly, front wheel covers/stays, and possibly an engine mount (still thinking if we should go with an aluminum sub-frame or just use some 3/4" round or square C.F. tube stock.)

I haven't had the opportunity to check on the body yet.... I should have an update by later tonight.  I'm curious to see how heavy this is going to turn out.  The first try only weighed 4 lbs.... this one has more carbon and will have a lot more glue in it, so if it's less than ~7 lbs, I will be happy.  I was hoping for a total body weight of less than 12 lbs, with no windows, but anything under 15 will be good.  My goal is to get the car under 70 lbs total... and there isn't that much to make lighter from last year.  We had even swiss-cheesed the fuse box, so some serious creativity will have to come into play this year to cut weight from the internal components.  I believe the body was 22 lbs last year with no windows.  I think we will save ~3 lbs on the frame, 1+ lbs on the seat belt, 1 lb on the fire extinguisher, 0.5 lbs on the windows, 50 grams on the starter ESC, 0.75 lbs on the axles......   but the tires are going to weigh an extra 900 grams.  And depending on which engine we run, it may lighter or heavier and which size starter motor we have to use. 

Based on a few team websites, it looks like a bunch of the teams who skipped last year's competition should be there this year.  I saw several teams with perfect carbon fiber bodies made with CNC cut female molds.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 22, 2013, 09:28:51 PM
I'm back give an update like I said I would on the body (a day late b/c of some crazy snowfall in the last 48 hours).

The body turned out really good.  I would rate it at a 9.5/10 considering that we did a wet layup with no vacuum and probably a 8/10 overall compared to any carbon fiber job, including vacuum set ups.  There are only a handful of spots where the carbon didn't sit down flat on the mold.  Luckily, many of those spots are where the windows go, so they will be cut out anyways.  Due to the wavy nature of the fabric, some spots may need to be filled in, but mostly likely a light sanding that just gets to the fibers and a bunch of primer should get the job done.

The tricky part for this Friday will be how to clean up the glue that dripped on the lower part of the mold before adding more carbon to the bottom of the car.
Title: Re: Treadmill Dyno
Post by: SparWeb on January 25, 2013, 01:14:00 AM
Random thoughts:

I can't see the release film all the way around.  It's visible on the wheel "pants" but nowhere else.  Problem?

Cardboard on the floor instead of plastic sheet?  Surely you can find a few empty pizza boxes, Mister Pizza Man!

Will the bottom lay-up be one big piece like the top, or will you try covering the wheel fairings separately from the lower shell?
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 25, 2013, 10:13:56 AM
Quote
I can't see the release film all the way around.  It's visible on the wheel "pants" but nowhere else.  Problem?
;D   The clear spots are actually packaging tape to hold the larger green sheets on.  I would say ~30% of the surface is covered in 2" wide packaging tape.  The glue doesn't stick to the back side of the tape.  We ended up doing the entire nose of the car with tape, since the green stuff doesn't lay down very well on two axis curved surfaces.  We liked to compare it to numerical integration....

Quote
Cardboard on the floor instead of plastic sheet?  Surely you can find a few empty pizza boxes, Mister Pizza Man!
Maybe,....  could be a little greasy, hence still slippery.  I have worked in fast food places with cardboard boxes covering the floor, and it does help some.

Quote
Will the bottom lay-up be one big piece like the top, or will you try covering the wheel fairings separately from the lower shell?
Probably not.  We can mostly likely get the insides of the wheel skirt, the bottom, most of the nose, and the rear wheel skirt in one piece, but the sharp edges+ curves of the wheel skirts/fairings would be impossible to drape the carbon fiber over all the way around.  The lower part of the wheel skirt on the outside is going to be interestingly non-structural for this car, unlike out last car.  The belly of the car and upper corners above the side windows need to be decently stiff.  If it is as strong/stiff as the cardboard in a cereal box, then I say it should be good enough.  Mounting the windows to a floppy surface is difficult, as we found out last year.  The bottom of the car will have our pre-made frame rails laminated to it, and we are counting on the carbon fiber


From last week, we were able to use a knife to peel off all of the messy glue drips and carbon strands that were on the lower part of the mold, so tonight we will definitely finish off the bottom of the car.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 27, 2013, 12:47:30 PM
Photo Update:

(http://i47.tinypic.com/jjmays.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 28, 2013, 09:11:55 PM
Photo Update #2.    Not too bad considering our limited resources and only gravity (or lack of it in the vertical sections) was holding the fiber on.  We were seriously thinking about doing the bottom in 3 stages by rotating the car on it's shish-kabob axis every 90 degrees, but the thumbtack idea seams to have worked quite well.

Most of the bottom is only 2 layers thick of 3K twill, with 3 layers on the very bottom where the main frame rail will be.  The bottom of the wheel skirts also have at least 3 layers, due to our super special wheel skirt design and the fact that we bottom out the car a lot (go figure!).  We are concerned that if our frame/suspension/steering snaps, the car would come crashing to the ground onto the wheel skirts.... which has happened many times with our previous cars.  If that happens in this car, the wheel skirts will collapse and the wheels will rip through the inside wheel covers and the top of the car, causing some serious damage and probably scare the living daylights out of the driver before coming to a grinding halt.

I hope to make the rear parts of the tail and wheel skirt more pointy when we add the filler to the surface.  In general, I am pleased with how the shape of the car turned out, especially how the tight radius above the front wheels turned out and progresses to the round tail area.  Looking at that curve on the computer was not easy and the white drywall had very little contrast to it to see the shape.   

(http://i49.tinypic.com/2lm6ntj.jpg)

(http://i50.tinypic.com/2whkwpk.jpg)

(http://i49.tinypic.com/2dchhmb.jpg)

Title: Re: Treadmill Dyno
Post by: electrondady1 on January 29, 2013, 07:43:05 AM
the shape is vaguely orca like.
should slide through the air nicely.
congrats.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 02, 2013, 05:40:06 PM
the shape is vaguely orca like.
should slide through the air nicely.
congrats.
Mother nature knows best.  We think the new design will be ~40% more aerodynamic than last year's car.  I think the design gets close, if not rivals the best cars in the European competitions.  30% of this increase comes directly from the change in shape of the body (smaller cross section, much better wheel skirts, longer body, more bluff nose) and the other 10% (estimated) comes from improvements from a better construction (correct window shape, smaller seams), a more aerodynamic exhaust pipe, spoke covers, and a lot of secret stuff in the front wheel skirt area that I have never seen in a supermileage car.


Here is a close up of the lightweight filler we put on the bottom half of the car last night.  This was after we sanded out all of the high spots and dry spots from the surface.
(http://i46.tinypic.com/21axnop.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 04, 2013, 02:41:54 PM
Round 2 of of filler, plus some side by side photos.
We measured the car this morning and it's 4" longer in length, 1.5" shorter in height, and it should be 2-3" narrower in width.

(http://i50.tinypic.com/24ovvk8.jpg)
(http://i47.tinypic.com/2qs5ct3.jpg)
(http://i50.tinypic.com/2a9xxf7.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 10, 2013, 02:14:46 PM
Excavation of the foam  ;D

The body is much thinner than last year, but still plenty stiff enough since we didn't sand through any of the carbon strands this time.  We don't have the nose excavated yet, but I would say the lid is at only 1/3-1/2 as heavy as last year's.  It's also a bit shinier than last time, since we didn't use plastic food wrap that gets stuck in all of the folds.  I should have an awesome time lapse video of the excavation some time soon.

Sorry for the lack of a good inside picture.... I'm sure there will be plenty of those in the future.  Also, note that there was eventually about a foot of foam chunks under the car by the time we finished.  There was also 8' long 80-20 aluminum bar running the length of the car that we had to carefully work around and pull out.

(http://i46.tinypic.com/2h3zj0h.jpg)

(http://i49.tinypic.com/160ygh.jpg)

(http://i49.tinypic.com/1z3p4zq.jpg)

(http://i46.tinypic.com/213ooco.jpg)



Title: Re: Treadmill Dyno
Post by: taylorp035 on February 13, 2013, 10:32:35 PM
14.2 lbs total with all of the carbon, which beats our goal of 15 lbs set by Laval.  http://alerionsupermileage.ca/blog4.php/2011/05/26/a-little-gift (http://alerionsupermileage.ca/blog4.php/2011/05/26/a-little-gift)

Considering we used no vacuum and a wet layup and had to add filler, I would say we did a really good job.  I think the absolute limit would be close to 8-10 lbs for the shell, with approximately 5 m^2 of surface area if done perfectly.  It's certainly a lot lighter than any aluminum or steel body could ever be for the same stiffness.

Pictured here (just the body) weighs 11.4 lbs.
(http://i45.tinypic.com/1qkdmq.jpg)

Title: Re: Treadmill Dyno
Post by: SparWeb on February 14, 2013, 12:00:52 AM
Slick.

Will the driver be lying on his/her back or stomach?
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 14, 2013, 10:26:38 AM
Quote
Will the driver be lying on his/her back or stomach?
On his/her back.  Going head first would be extremely dangerous and very hard to steer the wheels.  Not to mention it being extremely uncomfortable and it would take too long to exit the car (10 s limit).  Yet I get asked this question by ~50% of the people who see the car for the first time.  Only the single person bobsleds do I think you go head first..... luge boarding has the person laying on their back.  The feet fit better in the small area of the nose than a racing helmet.

If the car crashed, it would be from the nose or a side rollover.  Our 2010 car hit a solid object at ~8-10 mph during testing.... and the nose deformed in about 6" and then bounced back.  Having your feet down there in that situation would be a lot better than your head.  Hence the 4 point safety belt to keep the driver in place.  A roll over happens less that you would think.... our cars tend to drift and slide before rolling over.  In the 34 years of the SAE competition, only one car has rolled over, and I think it was because it went off the edge of the road.... a a combination of a narrow wheel base, 26" tires and a high center of gravity.  I'm not sure, but I also think that was the car that caused the "natural" steering direction rule.... turning left requires turning the wheel to the right can be very confusing.  Not to say that Behrend hasn't done this before :)
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 23, 2013, 10:17:05 PM
The frame rail(s?) are now in the car, along with the roll hoop.  The entire frame rail weighs 1.76 lbs.... lighter than I bet any other team.
(http://i50.tinypic.com/142y68l.jpg)


Here it is after the glue and C.F. was applied, along with a generous helping of gravity to bend the rails down to the body.
(http://i49.tinypic.com/2myz2o3.jpg)


The only frame setup that could be any lighter would probably be a properly designed C.F. tube frame.  But spatial issues with having the frame around the driver would make this difficult and probably decently uncomfortable.  The 6" wide, 1/16" thick plate on the square tubes alone weighs 0.50 lbs.... making a hammock style seat with a tube frame would most likely be heavier, unless you very carefully used the bottom of the car as the hammock, and then use the tubes in compression to keep the car from collapsing.... just too many issues.  I like the simple 1" square tubes... if we need more stiffness, there are lots of ways to make it better without adding too much weight.
Title: Re: Treadmill Dyno
Post by: Frank S on February 24, 2013, 01:41:07 AM
Injecting high density foam into the tubing will stiffen them without much weight. High density urethane foam weighs 41 kg per m^3  2 tubes 1" by 1" by 6ft could hold only a couple of liters or about .082 KG.
  High density and low density foam injected into spars, ribs, booms & masts have been used on racing sail boats and aircraft structures for years to stiffen the members by as much as 300% in some cases depending on design shape.
 Without the use of foam in a leer jet it would need an engine from a 727 just to get off of the ground and the A380  could have never gotten off the ground no matter how many engines could have been strapped on to it   
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 26, 2013, 10:32:05 AM
There is some foam under the frame rail, mainly so the driver doesn't break the top panel when they step on it.

After reading through the last 8 pages of this thread, I noticed you guys never saw a picture of my big sprocket I machined for the drive of this car.
Specs: 180 teeth, 17.98" diameter, 2.2 lbs, 7075 Aluminum, good for 600+ lbs of tension on the belt.  Used with a  12mm wide Gates carbon fiber stranded timing belt that has Teflon coated teeth.
(http://i46.tinypic.com/31502vt.jpg)
(http://i50.tinypic.com/2wbt05u.jpg)
(http://i48.tinypic.com/1q03tw.jpg)
Title: Re: Treadmill Dyno
Post by: Frank S on February 26, 2013, 02:04:22 PM
Nice!
Title: Re: Treadmill Dyno
Post by: SparWeb on February 27, 2013, 12:13:39 AM
That is a beauty.
Is the intent for the spokes to be in tension or in compression when the engine drives the belt?

Oh, wait.  I forgot.  The answer to that is "yes".  Poorly worded question.  Try again:

"Which way is it supposed to turn?"


Do not tell us how much that belt cost.
Title: Re: Treadmill Dyno
Post by: Frank S on February 27, 2013, 12:41:34 AM
you just got ta love those programmable machining centers with their auto selection tooling carriages
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 27, 2013, 08:39:18 PM
Quote
Do not tell us how much that belt cost.
It's not that bad... about $50 shipped.  We have two just in case we snap the carbon strands or shred it on our clutches' bell housing.  Even though the belt is good for many times more power than we can put out, we feel it's the best belt because it springs back to shape when you bend it.... aka the energy is not just being absorbed by the rubber and being lost (nylon belts don't spring back).

Quote
"Which way is it supposed to turn?"
CCW, looking at the front side of the sprocket..... but I think we are mounting it backwards for the new car to get it closer to the tire.

Quote
you just got ta love those programmable machining centers with their auto selection tooling carriages
It took 8 days to machine it, on a mill with only 12" of travel in the Y direction.... so it had to be done in two halves and lined up perfectly (there is no room for error with the teeth alignment when working with large sprockets).  In total, there were 34 different g-code programs run.  To make things more interesting, the sprocket shifted twice while it was being machined.... so I had to sort out how far it moved and then I had to re-draw the sprocket to accommodate the change.... hence one spoke is 1.78 degrees out of alignment.

If a large enough CNC mill was used, the sprocket could be cut out in one day easily, with just one program (depending on how many lines of code it can accept...).

Quote
Is the intent for the spokes to be in tension or in compression when the engine drives the belt?

Oh, wait.  I forgot.  The answer to that is "yes".  Poorly worded question.
LOL.   It's a valid question.... we tried symmetrical spokes and they didn't seem to perform as well as this design.  We tried 3,5 and 6 spoke designs as well.  The best performer was a thin solid disk... but I don't feel like it would be stiff enough in the sideways direction.... which is a very real concern when dealing with our set up(we proved this by mounting a GoPro camera to the roll bar of the car and pointing it towards the drive belt while the car was driving to see what was really going on... the results were scary  ;D). http://www.youtube.com/watch?v=xerLzUMVG7o (http://www.youtube.com/watch?v=xerLzUMVG7o)
Title: Re: Treadmill Dyno
Post by: Frank S on February 28, 2013, 02:23:42 AM
it took 8 days to machine it, on a mill with only 12" of travel in the Y direction.... so it had to be done in two halves and lined up perfectly (there is no room for error with the teeth alignment when working with large sprockets).  In total, there were 34 different g-code programs run.  To make things more interesting, the sprocket shifted twice while it was being machined.... so I had to sort out how far it moved and then I had to re-draw the sprocket to accommodate the change.... hence one spoke is 1.78 degrees out of alignment.

If a large enough CNC mill was used, the sprocket could be cut out in one day easily, with just one program (depending on how many lines of code it can accept...).

I know full well about machines not being large enough LOL
  Once I made a proto type injection mold for a special tire. The rubber company didn't want to spend the $100k for a mold for their production machine and the tool & die maker would not consider making a mold to fit a 60 year old machine. I could lathe out the inner mold parts but for the main cavities I had to use my Bridgeport mill and a turn table.
 The 2 mold halves  had to mate up to .0005" not easy on a 40 year old 3 hp Bridgeport with a 12 x 60" table
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 04, 2013, 03:04:38 PM
I think it's finally time for the world to see the new engine design (two years in the making).  It is in the process of being machined right now and should be up and running in 2-3 weeks.  The only description I will give you right now is the left side is the intake.  We probably have 800-1000 hours of time into this so far.

(http://i49.tinypic.com/66l0fs.png)
Title: Re: Treadmill Dyno
Post by: Bruce S on March 04, 2013, 03:11:30 PM
Ah, double over-head cam with timing belt:).
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 04, 2013, 03:31:40 PM
But no poppet valves   ;D
Title: Re: Treadmill Dyno
Post by: Frank S on March 04, 2013, 03:45:50 PM
What about the heat transference from the exhaust tube to the timing belt? 
 Or am I looking at it wrong?
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 04, 2013, 07:23:20 PM
"What about the heat transference from the exhaust tube to the timing belt?" -  Yes... it can happen.  But the engine runs for only 5-10 seconds during normal operation, so the exhaust pipe hardly gets got.  On our testing dynamometer, it is designed to run for 2 minutes straight..... we bought two belts, so if one fails, at least we will have an idea of what we can and cannot do.  The engine sits under an air vent, so there should be plenty of cooling.  We will probably swiss cheese the living daylights out of the sprocket, so that should increase the cooling surface area.
Title: Re: Treadmill Dyno
Post by: Frank S on March 05, 2013, 05:56:12 AM
"What about the heat transference from the exhaust tube to the timing belt?" -  The engine sits under an air vent, so there should be plenty of cooling.  We will probably swiss cheese the living daylights out of the sprocket, so that should increase the cooling surface area.
I was just wondering because a friend of mine rotary cam valved an Olds quad 4 gear drove a super charger for the intake and hung a turbo off the exhaust.
 over 900 hp on the dyno but the entire exhaust side would get glowing red.
 but he was only looking at power out versus displacement for a few seconds of engine life.
 I only saw it run once for a few seconds and never saw it run up to full power or RPMs, but it sounded like a small turbo prop engine. but others were getting 900 to a 1000 hp using conventional valves. I always thought a pair of de-tuned quads to 500hp each would make an excellent  twin engine  light aircraft
Title: Re: Treadmill Dyno
Post by: SparWeb on March 05, 2013, 02:56:11 PM
I'm guessing there's a slot at the "left-hand" end of the exhaust tube, over the manifold.  As it turns its opening aligns with the cyl head allowing the exhaust gas out.  Counting teeth from crank to exhaust sprocket, I'd say it turns 1/2 as fast as the crank, just what you'd expect in a 4-stroke with 1 exhaust stroke every 2 revolutions.

I'll have to scroll back about 10 pages to see how this compares to the hints you were dropping last year.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 05, 2013, 04:37:16 PM
Quote
m guessing there's a slot at the "left-hand" end of the exhaust tube, over the manifold.  As it turns its opening aligns with the cyl head allowing the exhaust gas out.
There is a slot on the intake side and a slot on the exhaust side.  It is a 2:1 ratio.  The larger diameter pipe on the right is just an extension of the exhaust side, and is there so the exhaust pipe does not rotate.  There are 4 bearings in the design... two of them are obvious.

The previous hints would be located around page 7-8....
Title: Re: Treadmill Dyno
Post by: SparWeb on March 06, 2013, 02:59:54 PM
Quote
The previous hints would be located around page 7-8....

No way.  You never let on that you were considering a rotary intake/exhaust valving system.  That cyl head from last year had poppets just like any other.  This is totally new.  You will do away with the cam but you have to deal with sealing around the tubes against 100 atmospheres combustion pressure.  Heat is a transient problem, like you say, at least. 

Title: Re: Treadmill Dyno
Post by: taylorp035 on March 06, 2013, 03:42:52 PM
Maybe I should of said just page 7, before the overhead rocker setup.  And you're right that I haven't given out too much info on this before.

Quote
You will do away with the cam but you have to deal with sealing around the tubes against 100 atmospheres combustion pressure.
Yep.... a 16:1 compression ratio is a blast to deal with.  It's safe to say that the spark timing will be fairly close to TDC, else too much pressure could develop.  Our current prediction is sitting around 7 MPa for peak pressure.  The design allows for the combustion chamber to leak excess pressure if it gets too high.

Quote
Heat is a transient problem, like you say, at least. 
Heat and seal wear are the two main issues that make this hard to put into a production car (but both are certainly manageable).  That's why it's so cool that we found an application (supermileage car) that we can effectively not care about these issues.  Design life of the engine is less than 20 hours... more likely just one hour. 

Hopefully I will have a few pictures of the components soon... the block and rotary valve have not been started yet.

These examples should keep the curious minds spinning for a while:
http://ralphwatson.scienceontheweb.net/rotary.html (http://ralphwatson.scienceontheweb.net/rotary.html)
http://home.people.net.au/~mrbdesign/PDF/AutoTechBRV.pdf (http://home.people.net.au/~mrbdesign/PDF/AutoTechBRV.pdf)
Title: Re: Treadmill Dyno
Post by: SparWeb on March 08, 2013, 12:48:48 AM
Awesome.
Here's to Taylor and his team bringing a very cool idea to life!  (http://www.rigel.ca/gifs/cheers.gif)
Title: Re: Treadmill Dyno
Post by: DamonHD on March 08, 2013, 04:13:36 AM
Seconded.

And I raise my (virtual, it's a little early here) beer too!

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 08, 2013, 11:00:52 AM
Quote
Here's to Taylor and his team bringing a very cool idea to life! 
I can't wait.   There is going to be a lot of attention drawn to this once it runs.

Here is the progress so far.... carburetor mount, bearing spring assemblies, large sprocket and the exhaust pipe.
(http://i46.tinypic.com/qsqz4z.jpg)

(http://i48.tinypic.com/1o11dz.jpg)

It's scary to see how small the parts really are and how ridiculously stiff the springs are.... peak load on the valve from the cams will be in the ball park of 500 lbs!
Title: Re: Treadmill Dyno
Post by: SparWeb on March 09, 2013, 12:39:02 AM
And... They will hold a set of conrad bearings, which are clamped down on the turning shaft by the bolts.  Rather than pushing the conrad bearing against the bare shaft tube (which would crush it) you will have a reinforcing ring around it (not made yet).  The springs allow expansion (not that your motor will have much heat) and vibration and even leakage, like a pressure-relief valve, if necessary.  Those look like 1/4" socket-head capscrews.  Probably 60 ksi steel, so in tension only good for 1000 pounds...   ... I guess if the load is spread across the 4 of them there won't be any problems.  Again you avoid worrying about certain problems because heat doesn't build up (bearing grease, etc.).

Title: Re: Treadmill Dyno
Post by: taylorp035 on March 09, 2013, 11:55:54 AM
Quote
Those look like 1/4" socket-head capscrews.
They are 5/16, with no threads where the aluminum will be sliding.  The max loads were assuming a worst case scenario for the pressure on the valve (port + seal).  We will probably try out a series of less stiff springs until it stops sealing, which of course will greatly reduce our frictional losses and make the engine run smoother (if a 16:1 compression ratio with an ultra-light flywheel at low rpms could ever run smooth.....)


Quote
Rather than pushing the conrad bearing against the bare shaft tube (which would crush it) you will have a reinforcing ring around it (not made yet).
Correct.  The valve itself has a 1/8" wall thickness, so it shouldn't crush.  The exhaust pipe on the other hand is designed to be very light weight, so it could be crushed with just your hand.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 16, 2013, 04:05:22 PM
Super lightweight steering and suspension.  Everything is carbon fiber, except for the ball joints, thrust bearing, nylon bushings, and the shaft clamps.  The suspension part isn't quite done yet.

(http://i47.tinypic.com/4m540.jpg)

(http://i47.tinypic.com/2571wg0.jpg)



The front window is going to be thermoformed on Monday :)

Here is an awesome time lapse of making the body.  ~12,000 photos in total over 4 weeks.
http://youtu.be/UVbKQQ1BkuU (http://youtu.be/UVbKQQ1BkuU)
Title: Re: Treadmill Dyno
Post by: DamonHD on March 16, 2013, 04:51:41 PM
Good video, good teamwork, and good fun it would seem!

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 20, 2013, 12:29:41 PM
We tested the power draw for our new dual spark ignition system and it only pulls 1 watt while running.  The old coil system was using up to 150W while running.   We also sorted out some low voltage cut off limits for our brushless speed controller for the starter motor, so now we can run our 1100 mah LiFE cells.  At full power, the starter pulls about 30A, which is asking a lot from those cells since the A123 cells never really did perform to their specifications.

Here is the steering in the car.  It fits just like the CAD model said it would.... with basically no clearance.  Currently, the axles rub on the outside of the body, so that will have to be adjusted a little bit.  Else, the firewall and side windows should be cut out this week.
(http://i49.tinypic.com/2wns680.jpg)

The first attempt at the front windshield did not work out very well, so a bigger thermoforming machine and a larger piece of plastic will be tried next week.  The hard part is obtaining the plastic in the first place since it is so thin.  This is turning out to be a very expensive proposition to get this thing made.... three orders for plastic and three nose molds have had to be made and resurfaced multiple times  :P  But it will be worth it to have a properly curved windshield, both for looks and aerodynamically.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 30, 2013, 04:03:55 PM
Picture of the wheel skirts cut out, along with the giant areas for our wheel flaps.  There will be doors that cover the holes when the car is driving straight.  Tire changes will be a lot easier than last year, with it taking only about 10 seconds vs. 1/2 hour.
(http://i50.tinypic.com/1051v1z.jpg)


I guess the rest of the new stuff is still not ready for pictures, like our paint scheme and the visibility from inside the car.  The rotary valve engine should be assemebled by late next week.

Here is a video of the suspension being tested.
http://youtu.be/K-E2IrESWnA (http://youtu.be/K-E2IrESWnA)
Title: Re: Treadmill Dyno
Post by: bart on March 30, 2013, 06:05:23 PM
   Hardly ever post on this thread, but ALWAYS look!
To cool and great work!
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 30, 2013, 07:47:16 PM
   Hardly ever post on this thread, but ALWAYS look!
To cool and great work!
Thanks!  Major changes to the car should come more rapidly over the next few weeks as we get the rear sub frame, drive wheel and engine in the car.  Then we get to test drive it to see if all of our new ideas were good ones :)

And I decided that you guys could see our visibility situation and show you why a taller driver like me isn't going to drive.  As you can't see, my knees are directly in my line of sight forwards LOL!
(http://i48.tinypic.com/2nl5m60.jpg)

Things will be much brighter inside once the very long side windows are cut.
Title: Re: Treadmill Dyno
Post by: SparWeb on March 31, 2013, 11:44:28 PM
Maybe (just maybe) the wheel fairings can be covered with a transparent material, which would allow much more side visibility.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 01, 2013, 09:45:49 AM
Maybe (just maybe) the wheel fairings can be covered with a transparent material, which would allow much more side visibility.
They were clear in the last car, and they worked quite well.  The tricky part will be the new spoke covers for this year, which will probably be clear red due to a lack of choices where we bought the heat shrink material.  That will have to be evaluated later.

Here is what it looked like last year.  Obviously there is issues with everything getting dirty and reducing our visibility.
https://orgsync.com/22440/photos/albums/22949/photo/446349 (https://orgsync.com/22440/photos/albums/22949/photo/446349)

Two years ago, it rained and our windows became very foggy, reducing visibility to almost zero..... the RainX and anti-fog wipes didn't help.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 08, 2013, 07:11:40 AM
Shell Ecomarathon was just completed and it looks like Laval has raised the bar yet again with a spectacular finish of 3587 mpg, breaking the old record set at SAE supermileage of 3169 mpg.  I would also like to note that they did this on a track that in my opinion is worse for fuel mileage than at supermileage.

I think our car will be able to match theirs, since I think our aerodynamics will be better and we should weigh about 20 lbs less.  I would say they will probably have the more efficient engine, but we will have to see how the rotary valve engine does by the end of this week once we get it running.  Everything else should be equal, but who knows..... some of the finer details can be very important, of which I'm sure they are well aware of.
Title: Re: Treadmill Dyno
Post by: Bruce S on April 08, 2013, 07:58:12 AM
WOW! and here I am enjoying the hypermilage tricks I use to get above the 36/mpg in my 2010 Chevy :).
A point of curiosity? How long would the engine last merely sitting and running? not stop /start stuff but running. Say as a stress test of the heating/cooling of the engine and components.
Awesome stuff! 
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 08, 2013, 08:57:16 PM
Quote
A point of curiosity? How long would the engine last merely sitting and running? not stop /start stuff but running. Say as a stress test of the heating/cooling of the engine and components.
A stock L-head, air cooled with the vent not over the fins: ~30 minutes of dyno testing.  At which point the oil starts to steam out of the crank case and the head temperature reaches 425F +.... not good for an aluminum engine.
A stock L-head with no oil: ~30 minutes before the cylinder lining and crankshaft surfaces are completely scored and ruined.  Then the rings will break....
Last year's OHV rocker 12.3:1 C.R. engine: about 1 minute at full  throttle (~3.3 hp) and it was up around 270F from room temp.
This year's rotary valve: ?  I'm guessing maybe 30-60 seconds.  The teflon in the exhaust bearing will melt first when it gets up above 500F.  The graphite port seal should  hold up well.  The piston will probably melt first due to the very high combustion temperatures and lack of cooling.... of which may be compromised if we decided to eliminate the oil in the crank case.  The new engine will also probably have all of its fins cut off and wrapped with insulation to keep it warmer ( as if a 150F engine compartment with no airflow wasn't enough...).  I think we should study the effects of a cold air intake by putting our 1500W heat gun up to the carb.....

If you had a stock engine with it just sitting, running say at 1 hp, then it would probably run forever until the oil turned into sludge or the spark plug gets fouled or dirt gets into the carburetor jets.  Or in our case last year, the points wear out b/c we were running the ignition on 16v and 150W for a single spark plug.

Quote
WOW! and here I am enjoying the hypermilage tricks I use to get above the 36/mpg in my 2010 Chevy :).
Today, I tried my best going to work and improved my mileage by 20% over the previous day with 20.7 mpg in my Jeep.


We ran into yet another problem with thermoforming the windshield.... this time, we put the plastic sheets in a dryer to get the moisture out over the weekend and when we opened it up today to use it, the plastic was all melted together in a big mess.  So, attempt #3 with mold attempt #4 will be tried this Thursday.  On the plus side, the rotary valve head should be done, so I hope to personally assemble it tomorrow afternoon.

Here is the rotary valve :)
(http://i50.tinypic.com/n3llpg.jpg)

And the unfinished assembly as of late last week:
(http://i47.tinypic.com/25gqo9e.jpg)
Title: Re: Treadmill Dyno
Post by: SparWeb on April 09, 2013, 02:53:59 PM
Are you sure you want to be showing pictures of the top-secret DARPA-sponsored ITAR-restricted engine valve?  ;)   Those foreigners at Laval might steal your technology!! 

More seriously, I'm a little worried about your schedule.  The engine's almost ready, but any dyno testing to tune it will take time, and exams are on about now.  Installing the engine, finishing the assembly, and shipping off to the racetrack all in the month of MAY is going to take some overtime shifts.
They're gonna call you Mr. Coffee Man by the end of this.
Title: Re: Treadmill Dyno
Post by: DamonHD on April 10, 2013, 05:11:28 AM
But universities *are* places for converting coffee into technology, yes?

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: electrondady1 on April 10, 2013, 07:44:46 AM
hard to believe, this is the same motor as my 1973 snow blower !
keeping my fingers crossed for successes .
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 10, 2013, 04:39:16 PM
Quote
Those foreigners at Laval might steal your technology!! 

Good luck trying to sort out all of the problems in just a month and then test it.  Let alone trying to obtain the parts that went into it.

Today, we glued in the port seal and the rest of the machining should have been finished... last I saw, the head was getting milled down to thickness and all that was left was the spark plug holes... of which are not going to be fun.  It's really cool to be able to see light through the inside of the carburetor :)  Before the engine runs, it will need some pins in the cams and a belt tensioner will need to be designed/made.

(http://i47.tinypic.com/hvdic7.jpg)

(http://i45.tinypic.com/24vmqzn.jpg)


Quote
More seriously, I'm a little worried about your schedule. 
I say we are on schedule for driving the car around in about a week.  Today, we finished the tabs for the front wheel flaps and they turned out really good, so the body will be smooth up front.  Everything else is pretty much built.... just the final wiring and attaching the little things to the car.  The front wheel covers should go in this Friday, along with some final body filling and sanding.  The side windows were cut out last week and the front window is still being worked on, but it's looking like next Thursday for that.  I think this year, we have decided to not use marine epoxy for the windows, just packaging tape on the inside.

Quote
hard to believe, this is the same motor as my 1973 snow blower !
Yeah, it's a really old engine design.  They haven't really changed the shape of the L-head much, but over the years, Briggs has updated the internals, like the piston and the crank bearings.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 13, 2013, 08:41:55 PM
Update:
The engine is almost ready to run.  The belt tensioner is halfway done and we received two new sets of springs to play with that are a 2-3 times less stiff to keep the valve in place.  We also installed the larger starter motor for initial testing (obvious reasons :) ), with plans to run the super mini starter later.  The rotary valve seems to be holding compression to some amount, so that's good news, which also must mean the head gasket and spark plugs are sealed.
(http://i47.tinypic.com/2enuv5s.jpg)

On the rest of the car, the supports for the internal front wheel covers were installed, along with some work on the front steering and the rear tail light windows.  The computer for the car should be done this week too.

(http://i50.tinypic.com/delic9.jpg)


I was doing a little math, and it looks like we only need 1.2 hp at 20 mph to get the acceleration that I was looking for and still be at approximately half of the available traction on the rear wheel.  The cool thing is that the calculations suggest about 1.2 hp at 3k, so let's hope they are right.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 14, 2013, 08:07:10 PM
The day has finally come!


EDIT:
More info will come once we put a load on the engine and get some numbers out of it.  It took us 3 hours today before it even kicked once.  I was surprised by how smooth and quite it was.  It sounds just like a normal engine... I was thinking the hollow pipe would make a funny sound, but it didn't.
Title: Re: Treadmill Dyno
Post by: bart on April 14, 2013, 09:21:32 PM
   Sweet!
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 16, 2013, 09:54:45 PM
Video #2 from today, with some more rev's this time around and  visible tachometer (x10 scale) on the right that works 30% of the time.


It was going well initially today and then it decided that it didn't want to start anymore.  So after 2 hours of cranking it over, we ripped the whole thing apart and found this:
(http://i46.tinypic.com/2efpdol.jpg)

The graphite seal should reach all of the way to the top of the aluminum head.... hence we had a giant vacuum leak.  The graphite was only 0.025" thick there and it was the leading edge, so I was actually surprised it lasted this long.  A new seal will be made from oil impregnated bronze ASAP, but until then, we filled in the gap with some JB Weld, so it should run tomorrow.  Then it should get hooked up to the dyno for some WOT runs :)

For scale, the head is about the size of a deck of cards, maybe a touch longer.  This picture was after we had cleaned the vast amounts of oil and graphite dust off of it.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 17, 2013, 03:29:25 PM
The JB Weld and a combination of super glue worked for about 30 seconds for the 3 times we made it run today.  But then the JB Weld would crack and we would have a vacuum leak.  A bronze seal should be made tomorrow.

Here is today's video, with even higher rev's and a view from the backside and up close.

Title: Re: Treadmill Dyno
Post by: SparWeb on April 18, 2013, 02:50:47 PM
Did you also mention "Teflon" a few pages back, or am I thinking of something else?  I'd examine that too.
Agree with the choice of brass.  If fact, here it is in the BOM on a drawing right beside me!

Any other scoring or damage worth mentioning so far?
Title: Re: Treadmill Dyno
Post by: Frank S on April 18, 2013, 03:43:16 PM
in looking at your design I think I understand the idea of using a cam action on your rotary valve. Correct me if I am wrong but in your application you are using the lobes of the cams to increase the sealing capability. If this is the only reason for having them then it appears you are creating a percussion effect on your seal which if this is the case any material with a density substantial enough not to be effected will create  higher friction and cause wear.
 would it not be better to reduce the lobe height and round out the apex of the lobes to a larger smoother radius?
 A friend of mine about 15 years ago was working on a rotary valve for a 4 cylinder engine
at first he tried a pure cylindrical tube valve he eventually wound up with a complex system but it worked
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 18, 2013, 05:38:46 PM
Quote
Did you also mention "Teflon" a few pages back, or am I thinking of something else?  I'd examine that too.
Agree with the choice of brass.  If fact, here it is in the BOM on a drawing right beside me!

We did mention teflon.  We could still use it, but I was worried that it would wear too fast.  I would also have to check for thermal and bending stresses.  And the operating temperature is a little on the low side.  We are making a seal out of oil filled brass right now - SAE841 grade.

Quote
Any other scoring or damage worth mentioning so far?
Surprisingly no.  The wear rate was very low too, considering the amount we have run it.

Quote
Correct me if I am wrong but in your application you are using the lobes of the cams to increase the sealing capability.
Kind of.  The cams are there mainly to counteract the changing cylinder pressure, so the valve doesn't just fly off the top of the head.  Hence the actual force of the pipe on the seal is relatively low.

Quote
A friend of mine about 15 years ago was working on a rotary valve for a 4 cylinder engine
at first he tried a pure cylindrical tube valve he eventually wound up with a complex system but it worked
Interesting.  I have only seen 3 other 4-stroke engines with the valve shaped the same way as ours.  And all of them utilized a split head design with beefy bearings holding it firmly in place.  We obviously decided to skip the bearings and the top half of the head.  This greatly simplified the sealing situation.  But it also required a lot more calculations to make sure the valve was going to stay in place..... trying to accurately calculate the pressure inside the cylinder with no real world data was a lot of fun.........but a challenge I was happy to take up.  Spark timing and the volumetric efficiency play huge roles in the peak cylinder pressure.

I think I can also safely say that this engine is the highest compression ratio of any rotary valve engine at 16:1.  We might even try to go higher, but the calculations don't seem to support higher efficiencies.  Doing a rotary valve diesel engine would be interesting.

EDIT:
Thermoforming attempt #4 went a little better today.  The results were a windshield that was free of bubbles and about 70% formed in terms of shape.  The vacuum on the machine didn't get sealed around the plastic, so we had to make some modifications to the machine.  I have high hopes that it will work when we make the window early tomorrow morning.  We are also hoping to finish making the new port seal tonight.

EDIT2:
A serious thermoforming set up right here  ;D
https://d1q9wbuypc40mm.cloudfront.net/jx51e2zfzmsipf4.jpg (https://d1q9wbuypc40mm.cloudfront.net/jx51e2zfzmsipf4.jpg)



Title: Re: Treadmill Dyno
Post by: SparWeb on April 18, 2013, 07:24:43 PM
Quote
...oil filled brass right now - SAE841 grade...

That could crack under the action of the cams, too.

I was thinking of 36000 or 54400 grades (the "free machining" kind).


Quote
...A serious thermoforming set up right here  ;D

I've always wanted to build one of those.  The world needs more curvy shaped windows.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 20, 2013, 06:54:50 PM
Quote
I've always wanted to build one of those.  The world needs more curvy shaped windows.
Now the world has a few more:

The final product turned out halfway decent.  It's the right shape, but there are a few marks from the mold and it's slightly fuzzy due to a million microscopic bubbles.  I would give it a 7.5/10.  But from a functionality standpoint, it meets all of our requirements, including being super lightweight.
Title: Re: Treadmill Dyno
Post by: taylorp035 on April 21, 2013, 04:43:41 PM
This morning we managed to get the engine to run once with the dyno hooked up and it put out ~0.9 hp at 4100 rpm for about 5 seconds.  It was not at full throttle, and we have no idea what the AFR was.  But, if you scale the the stock honda gx-35 performance at 4k of 0.6 hp *53cc/35cc = 0.9 hp.  So we must be doing something right.

In this video, I would say the peak RPM was about 5,000.

Title: Re: Treadmill Dyno
Post by: taylorp035 on May 09, 2013, 06:56:04 PM
Sorry for the lack of updates the last few weeks.

After testing many glues to seal the main seal into the head, we finally settled on some copper infused RTV, which is good for 700F.  The real break through was how we applied the RTV and making sure there was enough in the cracks to actually seal.  Previous attempts showed areas where there was no glue.  The result of a well sealed engine is shown in the video, where the engine idles much better now and much more reliably.



In other news, all three wheels are now mounted in the car, and we decided shortly thereafter that the suspension was a too soft in the front and in the back.  So, some modifications have been made to make things a bit stiffer.  We also aligned the wheels such that they track properly and so that we can make the required 50 ft radius turn in both directions.  Next up will be testing the brakes, of which we may install a support to make sure the whole assembly doesn't just snap off the main frame rail.  This added support may also be designed to simultaneously act as an anti-sway bar, of which the car needs very badly.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 25, 2013, 11:39:20 AM
The new car driving for the first time.  I think this is the best supermileage video we have ever made.

Title: Re: Treadmill Dyno
Post by: bart on May 25, 2013, 01:03:47 PM
   Congratulations! Must be nice to see all that work paying off.
So when are the race (s)?
Title: Re: Treadmill Dyno
Post by: electrondady1 on May 25, 2013, 04:42:28 PM
it looks wicked Taylor , congratulations to you and your team.
Title: Re: Treadmill Dyno
Post by: taylorp035 on May 25, 2013, 05:20:34 PM
   Congratulations! Must be nice to see all that work paying off.
So when are the race (s)?
The competition is June 6th and 7th at Eaton's Proving Grounds in Marshal, MI.

it looks wicked Taylor , congratulations to you and your team.
  Thanks from the both of you!   I hope it works out the way we planned.  After last night's work session and testing, I think the aerodynamics and rolling resistance are as good as we have been planning for.  The tubeless radial tires are going to work.... we were very concerned that our large drive sprocket was going to be too large in diameter, but it looks like the belt clears the ground by ~3/16"   ;D  Next is to make one of the 3 engines we have work better than a stock engine.  Else, a stock engine will have to be fitted.  We also need some more starter batteries, as we have worn out / killed off too many of the ones we own.

As you can see, the correct shape from the thermoformed window is going to help a lot compared to last year.
(http://i39.tinypic.com/1z1tn6c.jpg)

To go along with some giant blue stripes going over the top, we are going to include a nice logo of our design on the side of the car :)  It will get spray painted on later this week.
(http://i44.tinypic.com/314fp7k.jpg)

Title: Re: Treadmill Dyno
Post by: Bruce S on May 28, 2013, 11:55:00 AM
Did you due a rolling distance ? how far after the engine is turned off does it roll even on standard roads?
Sounds wicked too!
 I like seeing the blue flame from the exhaust.  ;D

Title: Re: Treadmill Dyno
Post by: taylorp035 on May 29, 2013, 07:14:19 AM
Did you due a rolling distance ? how far after the engine is turned off does it roll even on standard roads?
Sounds wicked too!
 I like seeing the blue flame from the exhaust.  ;D


Well, on the test track, you drop 4 feet in elevation, starting at ~21 mph down to 10 mph, the car rolls for about 1.2 miles, but that could be farther with the new tires and aerodynamics.
Title: Re: Treadmill Dyno
Post by: SparWeb on May 30, 2013, 07:02:43 PM
That's a pretty blue flame!

Tell the kids you get thrust from afterburners.  :)
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 02, 2013, 10:41:43 AM
We made page 1B in the news paper!

http://goerie.com/behrend-students-build-ultrahighmileage-car (http://goerie.com/behrend-students-build-ultrahighmileage-car)

Today, we hope to have the new mini OHC engine running!
Title: Re: Treadmill Dyno
Post by: DamonHD on June 02, 2013, 12:13:41 PM
Good write-up, and a familiar-looking lab!

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 03, 2013, 07:13:05 AM
I thought it was an excellent article.  The layout in the newspaper looked really good.

Here is some action shots of the car driving.


Title: Re: Treadmill Dyno
Post by: electrondady1 on June 03, 2013, 07:50:54 AM
you call it "the sea cow" ?
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 09, 2013, 05:28:15 PM
We won yet again!   ;D   This time with a score of 1,290 mpg and a good design report score.  We actually took 2nd in terms of fuel mileage, where BYU achieved an impressive ~1,330 mpg, but they didn't fair so well on the design report score.  We believe this to be the first time the design report has actually swayed the 1st place winner.

you call it "the sea cow" ?
  Yes, it's nickname is the sea cow, since it looks like a manatee when it's upside-down. 


Here is a picture when we entered it into the "Most Visually Appealing Vehicle Contest":
(http://i44.tinypic.com/6r2djc.jpg)
Title: Re: Treadmill Dyno
Post by: Frank S on June 09, 2013, 05:44:10 PM
Great job  and congrats
did you use your rotary valve engine or the conventional head design?
would be interesting in reading about an after race tear down evaluation
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 09, 2013, 06:34:30 PM
Great job  and congrats
did you use your rotary valve engine or the conventional head design?
would be interesting in reading about an after race tear down evaluation
We used last year's 12.3:1 CR rocker push rod engine with the stock 148 cc block.  The rotary valve and our mini OHC engine did not run well enough to be put into the car.

As for an evaluation, I would say the car was only rolling at about 60-70%, due to poor steering alignment and us having problems with our tires all day (we went through 4 tires, mainly due to not having rim tape on one of our rims).  The engine was also not being very efficient, as I would guess in the 5-6% range.  We checked the AFR and it was exactly where we wanted it.  The weather was actually quite good, with 5-10 mph winds and 60F and minimal sunshine.  Given another shot, I bet we could break 2000 mpg no problem.  At the beginning of the day, we had guessed 2507 mpg, of which we thought was the most likely score for us since there was a $100 prize involved.

We had plenty of other problems to contend with also, including smoking our ESC for the starter, exploding a starter pinion gear, and fighting a brushless starter motor that the coils had been overheated.  It didn't want to turn the engine over very well.  We also had to replace our front windshield, as we couldn't see worth anything out of our thermoformed one.  The ground clearance between the drive belt and the ground was only ~1/16", which  made it hit a lot of little rocks while driving.  We later switched to a larger diameter tire to fix this problem.  We made of total of 6 runs, with 3 being good.  The 3 failed runs were caused by a flat tire, a broken starter pinion, and another flat tire.

Here is a video of the mini OHC engine in action.  You can read more about it in the description on the video.
Title: Re: Treadmill Dyno
Post by: Frank S on June 09, 2013, 09:52:10 PM
Thanks; Will you be involved again next year or is it time for you to pass the torch on
Title: Re: Treadmill Dyno
Post by: bart on June 09, 2013, 11:26:25 PM
   Congratulations to you and your teammates!
Great to see all that hard work pay off with a win.
Title: Re: Treadmill Dyno
Post by: DamonHD on June 10, 2013, 05:43:49 AM
Yes, congrats!

Rgds

Damon
Title: Re: Treadmill Dyno
Post by: SparWeb on June 11, 2013, 12:16:26 AM
I think Taylor is too modest to post this photo of his teammate hoisting the trophy:

(https://d1q9wbuypc40mm.cloudfront.net/zmrns1gikxw1r7d_710.jpg)
(I found it on the teams' website).

Earned with all the perspiration and inspiration that the great Edison valued.  Way to go guys!   :D
Title: Re: Treadmill Dyno
Post by: Bruce S on June 11, 2013, 09:44:06 AM
CONGRATS!!
Yet more proof and persistence will pay off!
I also like the Safety banner in the back ground  :).
3 CHEERS!
Bruce S
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 11, 2013, 08:35:13 PM
Hmm... I wasn't expecting someone to post my own pictures LOL.  We are still trying to upload all of the photos, of which me with the trophy is not up there yet.

Thanks; Will you be involved again next year or is it time for you to pass the torch on
No, I graduated a few weeks ago, so no more supermileage for me.  There are lots of great students who will have the chance to do even better.

The cool part is that the up and coming students get to start off with a great car, unlike when I started and the car was a tank.  Now with that being said, the engine department has a lot of potential to be made better.... an easy 200-300% I would say.
Title: Re: Treadmill Dyno
Post by: SparWeb on June 14, 2013, 01:13:38 AM
Quote
... We are still trying to upload all of the photos, of which me with the trophy is not up there yet...

Yes I didn't think it was you - unless you've gained weight and shaved your head!!!

So you never mentioned your major through all this - M.E. I assume? ...or EE?  IE?  CE?
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 15, 2013, 04:16:30 PM
Quote
So you never mentioned your major through all this - M.E. I assume? ...or EE?  IE?  CE?
I am a mechanical engineer.  About half of the team is also M.E.  We also had a few E.E.'s and computer engineers.  The club used to be almost entirely MET's, but that stopped around when I started 4 years ago.  I think the MET's valued more the high horsepower tuned engine designs  than the now tiny, fuel efficient engines we put in the car today (the cars used to weigh 200-400 lbs).  It was a very strange shift, because the adviser is a MET faculty member.  In my opinion, the MET's are just as capable as the ME's when it comes to making a car.

The team members who end up staying with the club are of the type who like making their own projects and like to work with their hands.  As you guys are probably well aware, it's hard to find people like that today.
Title: Re: Treadmill Dyno
Post by: SparWeb on June 16, 2013, 07:20:28 PM
Then you may be facing the work-place soon.  Totally different set of challenges.  Good luck to you there, too. 

I'm thinking of my situation upon graduation.  I also needed a bit of time to finish the heavy-lift aircraft competition I was in (like the SAE comp.), before getting to my first "career" job.  I count myself lucky to have landed where I did, a near-perfect match, but most of my classmates weren't so fortunate.  That was back in the 90's, and I don't think anything is much easier for graduates these days, either.  Over the years I helped 2 other guys from my school hired into the company I was working at, but it was very hard keeping track of the rest.

Title: Re: Treadmill Dyno
Post by: taylorp035 on June 17, 2013, 09:17:00 PM
Quote
Then you may be facing the work-place soon.  Totally different set of challenges.  Good luck to you there, too. 
I landed a full time job 3 months ago at the place I wanted to work.  My good grades, the supermileage car and several good references inside the company made things easier (but by no means a walk in the park).  A 3.9 or 4.0 GPA does not get you into the company I work for.... they were looking for a particular type of person/engineer.

The job fairs for the engineers were pretty good once I became a senior.  I would say that most people got a job of some sort.... many of the jobs required re-locating down south where they need a lot more engineers than up here (Exxon, FMC,....).  All really good paying jobs if you wanted to re-locate.  Some of the local job offerings were much lower on the pay scale.  Non-engineering majors definitely had a much harder time getting a job.  PLET's all pretty much have three job offers without even submitting a resume. 

Having "Penn State Behrend" on the top of my resume holds a lot of weight when compared to other schools, even University Park students.  If I couldn't find a job at one of the ~130+ companies that came up for the fall and then spring career fairs, then I could go to UP where they have somewhere around 1,000....


Here is a picture of why we didn't get as many MPG as we were hoping for...   I have another super blurry picture showing the flame extending about 12" past the end of the ~10" exhaust pipe.  As you could imagine, this is not very efficient  ;D  But cool, most definitely!
(http://i41.tinypic.com/2jayp13.jpg)

And a video looking into the combustion chamber while it was running...... just like looking directly at the sun, you should only do this with the proper safety attire on  8)  <--- AKA safety glasses and/or do the looking with a camera!


Title: Re: Treadmill Dyno
Post by: SparWeb on June 20, 2013, 01:13:47 AM
Quote
I landed a full time job 3 months ago at the place I wanted to work. 

Then I guess it's time for you to join the big leagues:   www.eng-tips.com 
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 03, 2014, 11:26:38 PM
It time to bring this thread back :D  The rotary valve engine 2.0 will be made soon.  This will be completely homemade, based on a 1940-1950's B&S model N 2 hp engine.  2" stroke X 2" bore.  The new rotary valve head has been designed and the parts have just arrived.  1" diameter rotary valve, which is very large.  9.5:1 compression ratio and a single spark plug.  There are a lot of design improvements and several simplifications that have been made.  The end goal of this engine is to prove the design, not necessarily for high rpm or high horsepower.  If the head works well, a new lower end to the engine will be figured out so speeds can hit 10-12k rpm, from 3600 rpm for the current design.  The valve and carburetor have been sized to handle the future increase in power.
Title: Re: Treadmill Dyno
Post by: Bruce S on January 04, 2014, 10:44:17 AM
This looks like it's gonna get interesting!
Is it once again for school competition?
Title: Re: Treadmill Dyno
Post by: SparWeb on January 04, 2014, 11:32:46 AM
Welcome back, Taylor   (http://www.rigel.ca/gifs/wave.gif)

I look forward to seeing this.  And hearing it: somewhere between the piston pulse and the valve whirr.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 04, 2014, 11:59:10 AM
Quote
Is it once again for school competition?
Nope.  Personally funded and no rules to go by  ;D

Quote
Welcome back, Taylor   
Thanks!  It's been a while since I have had the luxury to play with a windmill.  A new generator will have to be procured for double duty as a dyno and a windmill again.  I might go the extra large brushless outrunner motor route since I own a lot of large scale RC equipment.  I'm thinking of a motor doing double duty as a starter motor and generator, all while being controlled by a radio controller.  That way I can hook up a servo to the throttle on the carb and vary the load without standing too close to the engine... as well as being really cool.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 12, 2014, 08:46:19 PM
Time for some progress photos.  This shows about $200 invested and about 40 hours time of machining (~9 days so far) between my brother and I.  I'm waiting for the carburetor to show up (19mm Mikuni) and I need to get a half link for the #25 chain and probably a new spark plug.  Having a working ignition system is always nice when you are making an experimental engine and don't have a starter motor.


There is a cross bar with some springs and bolts that is missing in this photo.  They will hold down the end of the two side brackets.
(http://i39.tinypic.com/2iraghw.jpg)

Combustion chamber with high temp o-ring.  You can see the mesh size from making the g-code.  It's actually quite smooth.  The peak of the combustion chamber is 0.300" from the deck of the engine.  2" piston diameter.
(http://i39.tinypic.com/2lm7yf8.jpg)


The lack of ball screws on our mini mill left the half-pipe shape about 0.005" too narrow, so we used the remainder of the precision ground steel and about 1/3 of a tube of valve lapping compound to go the rest of the way on a lathe.  Very smooth surface and most importantly, it is straight.
(http://i41.tinypic.com/2mx4pqx.jpg)


Here is the valve.  The two port holes are 110 degrees apart, causing 5.6 degrees of "valve overlap".
(http://i44.tinypic.com/2z4a3yr.jpg)


Breathing capacity is enormous when compared to the stock engine.  This shows the stock intake valve 100% open
(http://i40.tinypic.com/35irdxc.jpg)




Title: Re: Treadmill Dyno
Post by: SparWeb on January 13, 2014, 03:59:10 PM
Any thoughts about a lubrication system?  I know that it's meant to run sporadically, but if wear starts to show up (presumably on the half-pipe channel first) do you have a plan to lubricate?
Title: Re: Treadmill Dyno
Post by: electrondady1 on January 13, 2014, 07:31:03 PM

i see one port in the head
i see one diagonal  port in the rotating valve.
does this one angled port do both intake and exhaust?
looking forward to seeing the intake /exhaust manifold perhaps that will enplane
Title: Re: Treadmill Dyno
Post by: Frank S on January 14, 2014, 01:02:11 AM

i see one port in the head
i see one diagonal  port in the rotating valve.
does this one angled port do both intake and exhaust?
looking forward to seeing the intake /exhaust manifold perhaps that will enplane

 If you look at the pic where he is holding the valve you will see that it has 2 ports . the way a rotoray valve of this design functions would be for  the intake on one end and the exhaust the other.
Title: Re: Treadmill Dyno
Post by: electrondady1 on January 14, 2014, 08:45:41 AM
oh. ok. so the gasses enter/exit through the ends of that rotating shaft.
Title: Re: Treadmill Dyno
Post by: Frank S on January 14, 2014, 01:01:55 PM
oh. ok. so the gasses enter/exit through the ends of that rotating shaft.
  That would be how it is done works fine for a single cyl engine on an engine with more cylinders it would require a separate
 rotary shaft for intake & exhaust or a combination valve shaft per cylinder.
 Or that is how I see it.
   
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 15, 2014, 10:21:42 PM
That's correct Frank.  For multi-cylinder engines, the rotary valves would have to be perpendicular to the row of pistons/crankshaft.  Or, you can do two long valves, one being the intake and one being the exhaust.  I have seen both and they both have major advantages and disadvantages.  Obviously I haven't tried to take on such a challenge.


I finally got the last of the half links and two master links to finish off the chain drive tonight, along with a new spark plug.  Minus the carb, here is the finished product:
(http://i43.tinypic.com/dgs9q8.jpg)



We tried getting it to fire by spraying some gasoline into the intake, but it didn't do anything.  After a bit of inspection, we couldn't seem to get the spark plug to fire, even though it would shock you if you touched it.  Then I broke my pull cord.


Quote
Any thoughts about a lubrication system?
For right now, we just drip a bit of 5W-30 on the valve to get it wet.  If it needs more, then we might bevel the leading edge in the aluminum head a bit to hold more oil.  We could also essentially have an oily brush that gets dragged on top of the valve (slightly dangerous with the possible exhaust flames being present....).  My senior design project just had a graphite block with some tiny cross drilled holes and an oil reservoir.  That actually worked really well.   If all of that fails, then some tiny grooves in the surface of the half pipe or even pressurized oil could be done.  I don't think it will a huge problem given our experience with the first design.  Then again, we used 6061 for this head instead of the QC-10 aluminum, so it's a lot softer.
Title: Re: Treadmill Dyno
Post by: SparWeb on January 17, 2014, 12:42:52 AM
Quote
...we couldn't seem to get the spark plug to fire, even though it would shock you if you touched it.

Checked the electrical conductivity across interfaces - plug - head - cylinder body?
Title: Re: Treadmill Dyno
Post by: Bruce S on January 17, 2014, 08:19:45 PM
AND grounding!Aluminum always was an issue with spark plus even on 351 Cleveland "wedge: engines.
Try holding the spark plug on the iron part of the casting then see if you get a spark.
 
Title: Re: Treadmill Dyno
Post by: Frank S on January 18, 2014, 02:00:08 AM
I don't know what you are using for your ign system but if you are using the old contact points & condenser type the spark has always been tenacious at best on Briggs engines. I started using an EI  on all small engines after it came on the market . A far more powerful spark and reliable
 the link is a similar unit to the ones I've used in the past and I am sure there are better on the market
http://www.ebay.com/itm/Briggs-Stratton-394970-OEM-Magnetron-Electronic-Ignition-Conversion-Kit-/181294409276?pt=LH_DefaultDomain_0&hash=item2a35fd263c
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 26, 2014, 07:17:42 PM
It turns out the wires that I thought were to short out the ignition as a kill switch actually needed to be connected together.

So, once the carburetor was bolted, here are the results  ;D

http://www.youtube.com/watch?v=BUgktsKAOeM&feature=youtu.be

http://www.youtube.com/watch?v=oR26T07tPwM&feature=youtu.be


We broke a plastic elbow in the fuel line and the carburetor probably was getting too cold for it to run any more, so it never ran after this.  The 80 seconds in the 2nd video doubles our record for run time over our senior design engine.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 26, 2014, 09:48:01 PM
Some photos of the test rig.

(http://i42.tinypic.com/hs3inn.jpg)

(http://i42.tinypic.com/2912gqg.jpg)


Quote
Any thoughts about a lubrication system?  I know that it's meant to run sporadically, but if wear starts to show up (presumably on the half-pipe channel first) do you have a plan to lubricate?
After the initial runs today, just having the valve wet was enough for it to run for the 80 seconds without any signs of things getting dry.  I'm thinking a slightly heavier oil than 5W-30 will improve sealing.  Maybe some 80W-90 gear oil would be more appropriate as we get the engine up to temperature (what ever that turns out to be).  After 80 seconds, the exhaust and center of the valve was only 105-110F according to my IR temp gun.  Granted, it was probably 40-50 F when it started, so.....

Title: Re: Treadmill Dyno
Post by: taylorp035 on January 30, 2014, 09:34:48 PM
A video of the exhaust flames and a new record run of ~2:40.

http://youtu.be/f30jm4fZ64M (http://youtu.be/f30jm4fZ64M)
http://youtu.be/XmS5Y7dMQ1o (http://youtu.be/XmS5Y7dMQ1o)

After the long run, we disassembled the head and performed an inspection.  There were some burrs that had smeared around the valve in two places, but nothing too bad.  We shall see how it looks after a bit more running and if we need to make any changes to the oiling pattern.

We also re-balanced the flywheel by knocking off a fin since it was missing one.  In the long video, we tried to make it go faster, but the vibration went from almost nothing to quite bad in just a few hundred rpm's as we accelerated.  And then if you gave to much gas, it would 'pop' and loose it's combustion pressure.  On later runs, we cranked the springs down all of the way, but by then, the carburetor was too cold and it wouldn't start.  The exhaust was 200F after the long run.

Here is a frame from the exhaust video highlighting the flame inside the valve.  You can see the jet of fire shooting out 8)

(http://i61.tinypic.com/ohpkky.png)

If I can get my hands on a camera that does ~240 FPS or better, then I could actually see what's going on halfway decently.
Title: Re: Treadmill Dyno
Post by: SparWeb on January 30, 2014, 10:44:29 PM
Taylor,
I've been looking at the hinge arrangement you have on the head for a while.  Just mulling it over...

If I was to make a diagram of the valve tube, as if it is a beam (warning this is gonna sound like school again) I think it would look like this:

\/                              \/               -Bearing
------------o------------              -Tube
    /\^^             ^^/\                   -Head Journal


The bearing pillow blocks push down on the extreme ends when the screws are tightened, while the journal provides support inward from the ends.  The journal support is rather widely distributed, but I think you'd agree that the maximum concentration of the journal's force is just beside the bearings.  So that leaves the center portion unsupported, except for the stiffness of the valve tube.  And if you tighten the bearings down, doesn't the center of the valve tube move up?  That would increase the clearance, not tighten it.

Title: Re: Treadmill Dyno
Post by: taylorp035 on February 01, 2014, 07:13:21 PM
Yes, I agree 100%.  But I don't think the problem with it leaking has to do with deflection of the valve or head.  The problem is that the force caused by the cylinder pressure is actually greater than the springs.  I need springs that are 2-3X stiffer at least.... with the springs cranked down 50% of their length, it is only providing ~300-400lbf for an area of .77 in^2.  I have a feeling that the cylinder is actually very well sealed, so the 9.5:1 C.R. is actually happening.  This also doesn't account for any force caused by the oil between the sliding surfaces.

The 1" diameter valve has 1/8" walls and is exceedingly stiff since it's only spanning 4.5".  Deflection I believe should be less than 0.001".  The head is also very stiff, one of the reasons why I made it so thick.  The first version of the head was not very stiff and it was deflecting 0.010-0.020" once the head bolts were tightened down.  I believe the cylinder pressure and the springs made it deflect another 0.004".  The spark plug location for this head is much better too for stiffness.
Title: Re: Treadmill Dyno
Post by: SparWeb on February 01, 2014, 11:21:32 PM
OK
So a 10:1 CR will give 147 psi in the cylinder, without combustion, and the valve opening is (I guess) 2" x 1" rectangular area, then the force pushing up on the valve body (when not open) is 147*2*1= 294 Lb or roughly 300 pounds.  Springs are doing fine, then.  But when the engine is running, I thought combustion would cause a significant rise in pressure - about 5-10 times higher momentarily.  Memory fuzzy on details.  You must have factored that in, right?

What would happen if you weren't using springs? 
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 02, 2014, 01:35:22 PM
To start with, no-heat added pressure at 10:1 C.R. is not air pressure x 10.  It's much closer to an exponential equation using PV=nRT.  With no heat, it should be 342 psi @9.5:1.  With the fuel, it should be 441 psi.  The area for the valve opening is .77 in^2, so that works out to 441*.77 = 340 lbf on the valve.  With a richer air fuel ratio and depending on the spark timing, that pressure could be much higher.  Hence the reason engines knock when you get the spark timing too early.  For low speed and small diameter pistons with high compression ratios, advancing the timing from 5 deg BTDC to 10 deg could increase the pressure by 50-100% since the flame covers the whole piston area so quickly (relative to crank rotation).

We could skip the springs, but it would probably be harder to get a consistent force on the valve.
Title: Re: Treadmill Dyno
Post by: SparWeb on February 04, 2014, 12:27:34 AM
Right. It's been a long time since I've used "adiabatic" in a sentence.    :-[

Any risk to the engine if you do remove the springs?
Have you been adjusting the spark timing?

Now you're going to need a dynamometer!
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 01, 2014, 08:54:38 PM
Made it back to see the mini OHC engine run, after it experiencing poor performance right before competition last year due to an improperly sized carburetor and leaking poppet valves.  Now with all of that was fixed, a bunch of dyno runs were made and the results were pretty amazing.  The specs on it are 53 cc's, 14:1 C.R., nickel-chrome bore, and dual spark plugs with a SOHC.  Peak power recorded was 1.4 hp at 3,900 rpm.  With no load, it was able to idle down to ~550 rpm, which is pretty amazing for an engine that small.  At power levels above 1 hp, we were able to record efficiencies of 18-19%, with a peak of 19.7%, which is a record for us. Some more runs at the RPM's that it will see at competition need to be completed, but an average of possibly 11-13% seems to be where it's at right now.  Last year's engine averaged about 5% for comparison.  So far, we have not hooked up an O2 sensor for AFR measurements, so maybe there is a bit more efficiency to be found.  Adding an exhaust will probably help too.

Here is a video of it with no load.  Closer to the end of the video, we turn down the idle until it finally stalls out at ~500 rpm.  We really liked the sound that it makes.
http://youtu.be/hU5pT8_dWGY (http://youtu.be/hU5pT8_dWGY)



Title: Re: Treadmill Dyno
Post by: taylorp035 on June 15, 2014, 06:08:16 PM
The results from this year's competition was 1020 mpg and 5th place.  The car was rolling very well based on our calculations, which meant we finally have validated Michelin's rolling resistance numbers and our drag coefficient.  Unfortunately, the engine was running super rich, most likely due to the increased engine bay temperature when compared to our testing.  Our calculations figure a 5% average engine efficiency, which is way lower than we were hoping for.  Peak efficiency on the dyno maxed out at 21.7% before competition.  Our estimated engine efficiency should of been 11-15% for the race, but the carburetor wasn't tuned very well for the conditions.  Two blown tires halfway into the afternoon hampered the efforts to adjust the AFR.  For the last run of the day, the team gambled on putting the best tires on the car and it unfortunately didn't yield a better result (the engine was probably even hotter by that time).  Interestingly, it seemed like all of the other teams were having similar issues, as the best score was 1211 mpg... a very, very close set of scores by the top teams.

Penn State Behrend's car is the white one on the far right.  76.5 lbs weight, ready to run with fuel.
(http://i62.tinypic.com/54ccn5.jpg)
 
Title: Re: Treadmill Dyno
Post by: SparWeb on June 16, 2014, 12:41:54 AM
A good result even though not close to last year's high point.  Were there attempts to adjust A/F ratio by "shot in the dark" or did you stick to a gradual adjustment plan?
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 16, 2014, 07:04:44 AM
Adjusting the AFR is difficult, because during a burn, it varies widely, from super rich to super lean.  This causes the engine not to want to start.  Also, it's impossible to tune the AFR without the correct load.  The carb has an AFR screw for the low end and the main needle for the high end.  The carb needed the needle moved a bit, but once you do that, the AFR and idle screws need tuned a lot, making this a risky decision in the middle of a race day.  You can only drive the car on the track, so you wouldn't get many chances to tune the engine if you messed it up.   Also, the low end AFR screw is super sensitive, so it's hard to play with.  Varying air temperature for the intake also makes things a challenge, as the car heats up once the lid is put on.... this year, the nose of the car got so hot under where the front window was, that it was getting soft.  Some teams put aluminum foil under the driver's feet... I can't imagine that helps visibility out of the already sketchy windows.
Title: Re: Treadmill Dyno
Post by: SparWeb on June 16, 2014, 12:55:11 PM
So... next year's race will be in Nome Alaska?  ;)
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 16, 2014, 09:34:10 PM
It's interesting, because every year, the weather conditions are different, from windy to calm and then from cold to hot and sunny to stormy.  Yet most teams aren't prepared for varying situations.  Being able to have your car run at it's best in any weather condition is important.  In the 5 years I've been there, I bet the insides of the cars has varied from the coldest to the hottest by 100F+.  Just goes to show, learning how to make the best supermileage car takes more than a year or two...  it really takes several generations of students to pass on the knowledge of all of the lessons learned.

And another thing that is so great is that there is no perfect answer for a car and that there is always room for improvement.  A perfect car in the perfect conditions could achieve 6-10,000 mpg... yet only two teams in SAE history have cracked the 3,000 mpg barrier and only a handful to break 2k mpg. 
Title: Re: Treadmill Dyno
Post by: SparWeb on June 17, 2014, 01:28:48 AM
Did you install any sensors to help set it - oxygen / air flow / throttle position, etc.?

Did the unique valve system perform well?
Title: Re: Treadmill Dyno
Post by: taylorp035 on June 17, 2014, 07:15:04 AM
No, No, No, and No.  We had an external O2 sensor that we could clamp to the end of the exhaust pipe, but that's it.  Throttle position was up to the driver.  On our EFI test engines, we have MAF's, but not on the carbureted engines.  I have seen teams who have attempted a servo controlled throttle to vary the throttle % during a burn... fairly complex to effectively do so.

The engine in the car this year was the 53 cc SOHC ~14-15:1 CR custom head with dual spark plugs.  It ran very well and experienced no problems that we know of, just that the AFR was way too rich. 

The rotary valve for the SAE car has not been tried again.  It needs to be re-sealed and glued to be run again.  The only reason to do this is for the satisfaction to see it run, since no one would risk running it at competition.  My homemade rotary valve still needs some attention and probably a bit of tuning on the AFR front..... which is hard to do with no O2 sensor and a coil wrap pull start.
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 05, 2015, 08:29:23 PM
Here is a video of my personal rotary valve 3.0 design running.  Probably my best engine video yet.  Completed the whole thing over Christmas break.  This version of the engine already has more run time on it than all of the previous versions combined.  I can't wait to make a dyno for it.


https://www.youtube.com/watch?v=iW7MRZB7Ris&feature=youtu.be (https://www.youtube.com/watch?v=iW7MRZB7Ris&feature=youtu.be)

Version 3 has a floating bronze seal in the center that gets pushed up by the combustion pressure.  The springs are there to lightly pull up so it doesn't fall down during the intake stroke and cause a vacuum leak.  The engine was designed to be a 10.2:1 compression ratio, but currently is about 8:1 since the seal is up in the air a bit.  A compression test revealed a healthy 135 psi.

(http://i61.tinypic.com/2a4v81s.jpg)


In other news, we also found the reason(s) why our mini 53 cc engine wasn't very efficient at competition.  Basically, it was severely worn out, with the valves, valve guides, and valve seats pretty much past their usable lifespans.  A new set of valves, seats and some sleeves for the guides will get it back to new again.  This explains the halfway decent efficiency at high rpm's and very low efficiency at lower rpms.
Title: Re: Treadmill Dyno
Post by: SparWeb on January 10, 2015, 11:25:02 PM
Hey thanks for the update Taylor.
Gotta love the brass for journal bearings and the like.
But is it exposed to the combustion side of the chamber?
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 13, 2015, 07:16:17 AM
The brass piece is a cylinder that goes all the way to the combustion chamber.  It has the sparkplug, half-pipe journal surface, the port and the combustion chamber milled into it.  On the outside, there is an o-ring and some teflon backers for sealing.

The brass piece floats and is pushed up by the combustion pressure.  The springs prevent it from dropping back down.

(http://i61.tinypic.com/2ewzdy9.png)
Title: Re: Treadmill Dyno
Post by: SparWeb on January 15, 2015, 12:46:58 AM
The pipe is more complicated than I thought.  How hard is it to make?
Is it machined as one piece?  Can the machining of each path be completed from the port side, or do you have to do some tricky things at the bottom of the hole bored into the bar?  Now that I see the way the passages are separated, I wonder if maybe an insert that pushes in from one end would be easier to make.

Title: Re: Treadmill Dyno
Post by: SparWeb on January 15, 2015, 12:48:06 AM
You have too many files open Taylor.
If I did that on my computer, Inventor would crash!
:)
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 20, 2015, 05:36:25 PM
Last Friday, we clamped the engine to a table and let it run for 73 minutes straight!  The previous record was 6 & 1/2 minutes.  It was idling at 1100 rpm with a few minutes of goosing the throttle (up to 4k) and low as ~800 rpm.  For the last 10 minutes, we upped it to ~2k rpm... it finally got a bit hot on the exhaust end and I think burned the oil off the edge of the seal, which then greatly increased the friction and lead the end of the valve to turn blue (measured at 400F).  You could hear the #25 chain start to groan under load, so I shut it off.  The head/ block were about 260F, which isn't too bad considering the complete lack of cooling.  There were some bubbles in increasing intensity coming around the seal near the end, which leads me to question how well the o-ring held up.  I can't wait to tear it apart.  Next step is to put it on my friend's go-kart.

The pipe is more complicated than I thought.  How hard is it to make?
Is it machined as one piece?  Can the machining of each path be completed from the port side, or do you have to do some tricky things at the bottom of the hole bored into the bar?  Now that I see the way the passages are separated, I wonder if maybe an insert that pushes in from one end would be easier to make.

We've made two valves at this point.  Both started with precision ground steel, which takes care of the OD.  It is machined as once piece, drilled from both ends and then each of the openings in the center get milled on a mill or 4-axis lathe.  Generally, you can't mill the transition between the drill operation and the mill operation to be very smooth, so some dremmel work is required.  You can make the path better for air flow, but it increases the machining complexity.  A nice multi-axis lathe could do a better job... kind of like how custom intake runners are machined in normal engine heads for race cars.

Here is a video of my mini 4-axis mill cutting the valve.  The rest was done with a 3/4" drill bit.
https://www.youtube.com/watch?v=qBgn5FxVOYs (https://www.youtube.com/watch?v=qBgn5FxVOYs)


You have too many files open Taylor.
If I did that on my computer, Inventor would crash!
:)
That's nothing.  Running CFD, I pushed my laptop to 59 Gb of RAM used (16 Gb actual ram).  A solid state disk drive helps in that endeavor.  At work, at times I have had 40+ applications open at once (I do a lot of data mining across different programs) and it only has 4 Gb of ram and the motherboard tends to only allow me to use 2.2 Gb of it... the rest of it gets swapped to an encrypted  disk drive, which is really slow.
Title: Re: Treadmill Dyno
Post by: SparWeb on January 21, 2015, 11:11:15 PM
I fear you'll find a mess where the o-ring once was.  Hope the insert isn't too hard to get out.
Maybe a piston ring would work?


Title: Re: Treadmill Dyno
Post by: taylorp035 on January 22, 2015, 07:03:29 AM
I tore the head apart last night and everything looked just fine.  O-rings were good and the sealing surface wasn't too worn or had any major scratches.  There was some gooey tar in the combustion chamber and smeared around the valve, so we are going to advance the "cam" timing by a few degrees and see if that helps.  On the plus side, any carbon or tar build up helps seal it better.  While we had it apart, we machined the spark plug countersink so it's now flat, which should stop some of the leaking.  The exhaust was nice and clean, but the intake had some of the tar, so we believe some of the charge is going back into the intake while running.
Title: Re: Treadmill Dyno
Post by: SparWeb on January 23, 2015, 08:40:58 PM
Again, I'm impressed!  I really didn't think the o-ring would survive.

Have you given any thought to the air exchange process and how complete the burning may be?  Air/fuel mix swirling about the chamber - you seem to be equipped to do CFD analysis, so have you done any for this subject?  Have you done any exhaust gas analysis?  (Maybe you've mentioned it before...  this thread is getting really long!)
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 08, 2015, 06:06:48 PM
https://www.youtube.com/watch?v=8P_YTQQUN3A&feature=youtu.be (https://www.youtube.com/watch?v=8P_YTQQUN3A&feature=youtu.be)
Today's run.  Now about 2.5 hours of run time total, and approximately 1/4 gallon of gas total.

I haven't hooked an AFR gauge to any of my rotary valve engines yet.  I have done some CFD on version 1.0.  This afternoon, I just set up version 3.0 in CFD, so I shall see what it looks like, especially with a computer that is 3X faster and 4X more RAM to play with.

Mixing of the fuel and the air should be very good compared to a poppet valve configuration.

Version 1.0 theoretically had a volumetric efficiency of 107% at 3,000 rpm based on my basic simulation.  Here is a screen shot from it and a video of some particles from the end view.
https://www.youtube.com/watch?v=uG0dRqNiBQk (https://www.youtube.com/watch?v=uG0dRqNiBQk)
(http://i62.tinypic.com/2mzz8nm.png)
Title: Re: Treadmill Dyno
Post by: Mary B on February 09, 2015, 05:34:06 PM
Wonder if a timing chain might be better than that belt(looked like a belt anyway)? Looked a bit sloppy.
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 09, 2015, 07:13:58 PM
My current engine uses a #25 chain and a 2:1 ratio for the drive to the rotary valve.  Version 1 used a Kevlar stranded timing belt and we broke several nylon stranded belts due to the high loads from the aggressive cams that held the valve down.

(http://i58.tinypic.com/9fnpd0.jpg)

(http://i61.tinypic.com/2enaq76.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on February 21, 2015, 02:02:47 PM
Finally hooked the rotary valve engine up to the dyno and was able to do two runs.  Both were at full throttle.  The first one was just to measure peak horsepower, which yielded 2.4 shaft horsepower at ~3800 rpm.  Not bad considering the stock engine is only rated for 1.5 hp.  The second run, we did a fuel economy test and it yielded 13.4% efficient at 2.3 hp.  That kind of efficiency is comparable to a stock 3.5 hp briggs.  Both the peak power and efficiency numbers could of been higher due to a pretty large groove that was forming in seal and was causing it to leak.  After those runs, it was misfiring and not holding idle very well... so it looks like it is time build a new seal and possibly a new valve.  The current "valve overlap" between the intake and the exhaust is 5 degrees.  I plan on making that a bit more aggressive.  The question is how much.  I also need to question the heat transfer ability between the seal and the head, as it was pushing ~330F after the dyno runs.
Title: Re: Treadmill Dyno
Post by: SparWeb on February 21, 2015, 08:37:38 PM
That's excellent Taylor! 

The production of 60% more power implies the production of more heat (even considering any improvement in efficiency).  Many parts could be running hotter than they did, even the stock components.
Title: Re: Treadmill Dyno
Post by: taylorp035 on March 11, 2015, 07:05:24 AM
https://www.youtube.com/watch?v=RjvYnzo0Qe0 (https://www.youtube.com/watch?v=RjvYnzo0Qe0)

We designed and machined a new seal, now with 36 degrees(crankshaft) of valve overlap between the intake and exhaust vs the previous 11.  Now it sounds more like a performance oriented engine and shoots a few more flames.  It definitely seems to have more power,  and we can't wait to put it back on the dyno.  We also swept the shape of the port for better flow on the intake stroke.

Last night, we replaced the hoses and fittings on the fuel system so it stopped leaking, so we tried to use all the gas in the tank.  Managed to get the center of the valve up to ~550 F, at which point it decided it didn't want to idle much more.  I think the gooey oil that cakes itself to the valve and seal started to melt and caused more leaks.  The intake gases do a good job of cooling the one side of the valve and the part between the chain and the seal was about 350F.

(http://i58.tinypic.com/dxh53p.jpg)
Title: Re: Treadmill Dyno
Post by: taylorp035 on October 30, 2016, 11:14:46 AM
Bringing back this thread to show off the next stage of the rotary valve engine development!

Now in a 1999 BMW 328is 2.8L inline 6 engine.  A first in many respects, including converting a modern production car, an Inline 6, and a BMW. It has some fun features including muffler bearings, exhaust bearing coolant, coolant running through a floating seal around the sparkplug, contra-rotating valves, 6 velocity stacks with no obstructions going right into the cylinder, custom double bevel gear box with homemade "cam lobe", multi-tiered oiling system, and a fully re-mapped cooling system that has many clear hoses.

Over 700 components, fully integrated into the stock engine bay.......... so bolts right up to the exhaust, all the sensors and hoses and stock intake.  No programming of the ECU has taken place yet (many people said this would never work).  We machined about half the components ourselves to save cost, but the bigger ones exceeded the capacity of our tools so they had to be sent out.

I'm getting really close to taking it back to the dyno to see how she fairs.  Still working out some kinks, but it has over an hour of run time on it and about 3 miles of hard driving in my back yard and up and down my driveway.  There have been moments where it seems like it has more power than the stock engine.  Sealing seems to be much better than the ego-kart engines and it has good compression and spark.

And I have to give some congratulations for BMW making such a robust starter motor.....

https://www.youtube.com/watch?v=GdmzrVj9n7s (https://www.youtube.com/watch?v=GdmzrVj9n7s)

https://www.youtube.com/watch?v=_3egpax5sZI (https://www.youtube.com/watch?v=_3egpax5sZI)

https://www.youtube.com/watch?v=W7x-3fukxhE (https://www.youtube.com/watch?v=W7x-3fukxhE)

https://www.youtube.com/watch?v=gVU1jK0yono (https://www.youtube.com/watch?v=gVU1jK0yono)

https://www.youtube.com/watch?v=BYpECSaNMhE (https://www.youtube.com/watch?v=BYpECSaNMhE)

https://www.youtube.com/watch?v=10xnE8W3Qe0 (https://www.youtube.com/watch?v=10xnE8W3Qe0)

https://www.youtube.com/watch?v=-8iTKxYdLb4 (https://www.youtube.com/watch?v=-8iTKxYdLb4)

Title: Re: Treadmill Dyno
Post by: SparWeb on November 04, 2016, 01:30:51 AM
HAha!
If there was ever a reason for your "check engine" light to be on...

I'm glad I clicked on the last vid first:  Smoke and fire and blue flashes, oh my!
Title: Re: Treadmill Dyno
Post by: taylorp035 on January 29, 2017, 09:44:23 PM
A picture of the engine bay when it was a bit warmer outside.  It's waiting for timing belt #4 to be delivered and installed. 

(http://i67.tinypic.com/jiz9d5.jpg)