Author Topic: Treadmill Dyno  (Read 123916 times)

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ghurd

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Re: Treadmill Dyno
« Reply #27 on: February 23, 2011, 11:40:49 AM »
"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!
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Bruce S

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Re: Treadmill Dyno
« Reply #28 on: February 23, 2011, 12:32:27 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
 
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taylorp035

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Re: Treadmill Dyno
« Reply #29 on: February 23, 2011, 02:14:55 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.






Madscientist267

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Re: Treadmill Dyno
« Reply #30 on: February 23, 2011, 03:24:34 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
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ghurd

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Re: Treadmill Dyno
« Reply #31 on: February 23, 2011, 04:39:04 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)
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« Last Edit: February 23, 2011, 05:24:57 PM by ghurd »
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Bruce S

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Re: Treadmill Dyno
« Reply #32 on: February 23, 2011, 04:50:49 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

 

 
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Madscientist267

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Re: Treadmill Dyno
« Reply #33 on: February 23, 2011, 08:36:51 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
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taylorp035

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Re: Treadmill Dyno
« Reply #34 on: February 23, 2011, 08:51:09 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.



« Last Edit: February 23, 2011, 09:00:25 PM by taylorp035 »

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Re: Treadmill Dyno
« Reply #35 on: February 24, 2011, 12:03:46 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.
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taylorp035

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Re: Treadmill Dyno
« Reply #36 on: February 24, 2011, 12:25:07 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.

 

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Re: Treadmill Dyno
« Reply #37 on: February 24, 2011, 01:18:57 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.
No one believes the theory except the one who developed it.  Everyone believes the experiment except the one who ran it.

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taylorp035

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Re: Treadmill Dyno
« Reply #38 on: February 24, 2011, 02:37:50 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.

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Re: Treadmill Dyno
« Reply #39 on: February 24, 2011, 07:24:42 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.

Madscientist267

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Re: Treadmill Dyno
« Reply #40 on: February 24, 2011, 08:10:46 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
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Re: Treadmill Dyno
« Reply #41 on: February 24, 2011, 08:32:17 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.

taylorp035

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Re: Treadmill Dyno
« Reply #42 on: February 24, 2011, 08:37:15 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.


taylorp035

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Re: Treadmill Dyno
« Reply #43 on: February 24, 2011, 09:26:09 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).

Madscientist267

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Re: Treadmill Dyno
« Reply #44 on: February 24, 2011, 09:29:51 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

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zap

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Re: Treadmill Dyno
« Reply #45 on: February 24, 2011, 09:36:02 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.

Madscientist267

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Re: Treadmill Dyno
« Reply #46 on: February 24, 2011, 09:39:34 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
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taylorp035

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Re: Treadmill Dyno
« Reply #47 on: February 24, 2011, 09:45:19 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.
« Last Edit: February 24, 2011, 09:55:09 PM by taylorp035 »

taylorp035

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Re: Treadmill Dyno
« Reply #48 on: February 24, 2011, 10:01:51 PM »
Here are the tires we bought today:

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

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.

Madscientist267

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Re: Treadmill Dyno
« Reply #49 on: February 24, 2011, 10:05:54 PM »
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...
« Last Edit: February 24, 2011, 10:10:41 PM by Madscientist267 »
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taylorp035

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Re: Treadmill Dyno
« Reply #50 on: February 24, 2011, 10:11:16 PM »
Well, I'll be back hopefully on Saturday night, if not by Sunday.  I'm always open to ideas!

Bruce S

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Re: Treadmill Dyno
« Reply #51 on: February 25, 2011, 09:32:30 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
 
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taylorp035

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Re: Treadmill Dyno
« Reply #52 on: February 26, 2011, 10:13:06 AM »
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.


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 ????


We had to lift the light bulbs off the table, since it was vibrating pretty bad.



Here are some pictures after the sanding, but before the glue was mixed up.








« Last Edit: February 26, 2011, 10:27:46 AM by taylorp035 »

taylorp035

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Re: Treadmill Dyno
« Reply #53 on: February 26, 2011, 11:33:27 AM »
Here is the first video of the electric dyno in operation.  Later, we added more bulbs.

http://www.youtube.com/watch?v=dErZDp20kSM