E85 Compression Ratios

[U of S Engine]

Hey Guys

Not to pry for the alighty secrets of power making, but I am curious as to how high all you E85 burners have run compression ratios?

Also, with an F4, what size injectors would be advisable. We have 14.9lb for 100 octane, and by my calcs, the 19lb spares that we have lying around would work alright with ethanol.....

Any knowledge of what is involved in switching would be great. Thanks

Kevin
U of Sask

[U of S Engine]

Hey Guys

Not to pry for the alighty secrets of power making, but I am curious as to how high all you E85 burners have run compression ratios?

Also, with an F4, what size injectors would be advisable. We have 14.9lb for 100 octane, and by my calcs, the 19lb spares that we have lying around would work alright with ethanol.....

Any knowledge of what is involved in switching would be great. Thanks

Kevin
U of Sask

[Bam Bam]

E85 has an equivalent octane rating of about 100-104 octane meaning you would likely run into clearance issues on that engine (assuming NA) before detonation would be a problem.

[U of S Engine]

Just out of curiosity, would anyone be willing to share clearance numbers? We have been trying to measure piston to valve clearance, but are having troubles finding a suitable material to use for measuring with. The engine is a dead spare with 2 good chambers, so we are trying plasticine, with a coating of oil, and then try to measure the thickness after cranking it over by hand. We've only tried once so far, and we had too much , so it deformed excessively and left us with nothing to measure.

We'd like to mill the head .020" or so, still have to measure exactly to figure out how much we want to change compression. Any advice would be appreciated.

Thanks

Kevin Hall
University of Saskatchewan
Engine Guy
www.engr.usask.ca/~formula (http://www.engr.usask.ca/~formula)

[Charlie]

Sure, put in some lighter springs, turn to the TDC overlap stroke. Put a dial indicator on the tappet and push the valve into the piston, measuring actual clearance.

-Charlie Ping
Auburn University FSAE 1999-present

[Bam Bam]

For piston to head clearance your doin good. plasticine works well. however put in a couple small balls on the quadrants of the piston an then crank it slightly past TDC take the head off and measure. I use the depth gauge on the back of the verniers. It'll spear through the plasticine while it's still on the piston. Keeps you from screwing it up tring to take it off. If you wanna take the plasticine off dust the piston with a bit o baby powder or oil. is fine. As far as valves do what charlie said.

[U of S Engine]

I check out the piston to valve clearance, and I am finding about .042" on the intake side. I am curious as to what would be safe to run? How tight can we go with that? What are teams running for piston to valve clearance. I know for SBC, they say .040", but I think we are a bit more precise. Any feedback would be great, cuz i want to mill the head .020" maybe a bit less.

Thanks

Kevin Hall
University of Saskatchewan
Engine Guy
www.engr.usask.ca/~formula (http://www.engr.usask.ca/~formula)

[U of S Engine]

Has anyone changed compression ratios in the F4? If so how? Has anyone milled the head? How much is safe?

Thanks

Kevin Hall
University of Saskatchewan
Engine Guy
www.engr.usask.ca/~formula (http://www.engr.usask.ca/~formula)

[Charlie]

I was told Honda sells performance head gaskets to raise or lower compression. You mill the block and head, and use thier gaskets to achieve different compression ratios. Perhaps you can look into doing this and find out what thier minimum clearance is.

-Charlie Ping
Auburn University FSAE 1999-present

[Spike]

HRC makes "kit" headgaskets for the F4i and F4. That way you don't have to take any material off the head. It might be tough to get the HRC stuff because your local Honda dealer can't get it. HRC USA (http://www.hrcusa.com/hrc/hrcmain.asp) is the only place to get the kit parts in the US or Canada.