Fieldlines.com || Ethanol Engine (Updates once again)

Front Page - [Homebrewed Electricity-- (wind) (solar) (hydro) (steam) (controls) (storage) (mechanical)] - Classifieds - Site News
Everything - Newbies - [Remote Living-- (housing) (heat) (light) (water)] - Reviews - Diaries - Our Products

Ethanol Engine (Updates once again)
By Andrew, Section Homebrewed Electricity Posted on Thu Jul 10, 2003 at 11:24:10 AM MST
Engines coming along perfectly

Hi,
Brian asked how the engine was coming along.
Well, I got the reamers 2 days ago, so now I up and back to production.
I have most of the parts machined, but I'm rinning into some problems....
How do I make or get rings that small?????
Also, I cannot drill and tap the top of the cylinder, until I buy a glow plug, because of the chance that I might get the thread wrong.
Its stainless piston, aluminum head, and crankcase, and I'm still working on the carburator, so that might be aluminum too.
-Andrew

Ethanol Engine (Updates once again) | 9 comments (9 topical)

Re: Etanol Engine (Updates once again) (none / 0) (#1)
by Demetri on Thu Jul 10, 2003 at 12:17:28 PM MST

Hey Andrew, great to hear things are coming along! Most engines that size(and slightly larger, like my Magnum) don't use rings at all. The piston tapers towards the crown, so the diameter at the skirt is bigger than the diameter at the crown. As the engine runs and heats, the crown gets hotter than the skirt, and expands more, bringing the piston out to fit the cylinder. I'm sorry if you know all this already, but maybe you could do something similar? Good luck.

Demetri
Uncommon sense required.

Re: Ethanol Engine (Updates once again) (none / 0) (#2)
by TomW on Thu Jul 10, 2003 at 01:19:58 PM MST

Andrew;

May I suggest that you post future updates on this ethanol engine to your diary rather than the front page?

It just seems to me that is a better place for it rather than posting it to the front page every time it gets down the queue a ways. After all this is exactly the kind of thing the diaries are for.

Cheers.

TomW

The Truth is the Truth, even if no one believes it; and a lie is a lie even if everyone believes it

Re: Ethanol Engine (Updates once again) (none / 0) (#3)
by Andrew on Thu Jul 10, 2003 at 06:18:38 PM MST

I suppose, but it seems no one really pays attention to diaries, and it takes weeks for me to get a response.

As far as the piston, demitri, I did not know that. It seems like an interesting idea, but woudn't it be pretty hard on the piston? Also, it seems like it could seize really easy.

-Andrew

[ Parent ]

Re: Ethanol Engine (Updates once again) (none / 0) (#4)
by Andrew on Fri Jul 11, 2003 at 04:34:59 AM MST

Well demitri,
I used your idea.

YESSSS!!!!

I put the tapered piston into the head, and.... I made a gas spring!
No leaks!!!!
It will work beautifully in the engine.

I'm leaving for Wisconsin tomorrow, so I woun't be able to machine or make any progress on the engine until I come back on Tuesday.

From now on, I will post my progress on the diaries page.

For the glow plug, I'll wait until Brian gets back to me on the heat range.

Until then,

All is good!

Everything is panning out perfectly!

I expect this engine to be sputtering along late next week!!!!

It should make an interesting battery charger (probably only like 10 watts),
I picked out a hoover vacuum motor that is 6v at 10.5A, and should work beautifully for this application.

Thanks!

-Andrew

[ Parent ]

Re: Ethanol Engine (Updates once again) (none / 0) (#5)
by Demetri on Fri Jul 11, 2003 at 11:15:32 AM MST

I'm glad it's working out, hope you have fun in Wisconsin.

Demetri
Uncommon sense required.

Re: Ethanol Engine (Updates once again) (none / 0) (#6)
by Brian on Sun Jul 13, 2003 at 12:35:19 AM MST

I agree a tapered piston would work well, but we all know metal expands as it heats up. If the clearance between the skirt and the cylinder wall is too tight when the engine is cold, you could end up with a seized piston and a busted crankshaft if the thermal expansion isn't taken into account. If you know the exact composition of the metal you're dealing with, it's possible to calculate the thermal expansion of the piston so you can machine for the proper clearances at normal operating temperatures to ensure the engine will operate at temperature without excessive wear....or worse. The one good thing about burning ethanol as opposed to gasoline is the fact that the engine should run close to 40 degrees cooler which could lessen the thermal effects.

I would hate to see your hard work go down the drain, so just something to think about.

Regarding the temp calculations, you haven't given me the exact dynamic compression ratio so any numbers would not be accurate. Have you actually machined the intake and exhaust ports yet? I can't run the numbers without it!! :-)

I didn't see any intake or exhaust ports in your drawings, nor did I see an internal passage which would allow the pressurized fuel to flow from the crankcase to the intake. How will the fuel get from the crankcase to the cylinder?

Brian

[ Parent ]

Re: Ethanol Engine (Updates once again) (none / 0) (#7)
by Demetri on Mon Jul 14, 2003 at 10:00:39 PM MST

I'm sorry Andrew, I had it backwards. The cylinder in the engine I spoke of is tapered, the piston is straight. The top of the cylinder is ever so slightly smaller than the bottom, and when cold the piston actually binds a little at tdc. The best way I can think of to achieve this would be to heat the cylinder on one end to operating temperature, bore straight, and let it contract as it cools. Hope I didn't goof up things too badly. You might try running that piston anyway, I believe aluminum would expand more than stainless steel, your cylinder would pull itself away from the piston, probably allowing excess blow by but I doubt it will ruin anything. I'm really sorry, good luck.

Demetri
Uncommon sense required.

Re: Ethanol Engine (Updates once again) (none / 0) (#8)
by Brian on Tue Jul 15, 2003 at 08:22:52 PM MST

Yes, aluminum does expand thermally more than steel does. Mild steel has a thermal expansion coefficient of around 0.0000126/deg C and aluminum is around 0.0000240/deg C. These numbers will obviously change depending on the exact composition of the steel and aluminum. The above numbers have no unit of length associated with them either. Here's a sample calculation of how you would calculate the expansion of a mild steel rod.

Length of rod= 50 mm
Change in temperature= 200 deg C
Thermal expansion= 50mm x 0.0000126/deg C x 200 deg C= .126 mm expansion in all directions.

Andrew, I noticed you said you used an aluminum head and steel piston. Did you sleeve the cylinder? The steel piston against the aluminum will cause it to wear out pretty quick.

Good luck, Brian.

[ Parent ]

Re: Ethanol Engine (Updates once again) (none / 0) (#9)
by Andrew on Wed Jul 16, 2003 at 04:06:26 PM MST

I'm back!

No, I do not have a sleeve.

It would wear pretty quickly now that I think about it.

I'm going to have to machine the cylinder head. I'll make the piston out of aluminum, and a slightly taper piston, top being biggest, and then have the head machined out of stainless. Since the aluminum will expand about twice as much as the steel, I'll have large heat sinks machined on the side of the head. The aluminum should expand ever so slightly in the cylinder, thus the top being a perfect seal, and the bottom expanding to fit. About the seizing, I'll probably have to heat up the engine a bit before I start it, just so I avoid this problem.

I'll get back to you on where the intake and the exhaust ports will be.

Thanks!

-Andrew

[ Parent ]

Ethanol Engine (Updates once again) | 9 comments (9 topical)

Menu

� create account
� How to use the board
� FAQs
� search the board
� Google search the board

Login

Make a new account

Username:

Password:

Total Views

��42 Scoop users have viewed this posting.

Related Links

� Also by Andrew

You must be a registered user to post here. It's easy and free, and the link is on the upper right side of your page.
All trademarks and copyrights on this page are owned by their respective companies. Postings are owned by the poster, but may be deleted or moved at the ADMIN's sole discretion. The Rest � 2009 Forcefield.
You can Email the board ADMIN here. PLEASE include the username you signed up with!