Anyone running 11:1 CR using E85? Should make more HP on a stock IX turbo using E85? Any thoughts?

 

i wouldn't go any higher than 10.5:1... I haven't heard of 11:1 comp since I've owned a honda, thats more of an all motor comp. i think 10.5:1 is money and MAP carrys that in stock!

 

Would probably make good power, but at that high of a CR the cylinder pressures will be getting really high. I think a 10:1 to 10.5:1 engine would be a better option.

 

I run 11:1 on my hillclimb car. For a DD its likely too much of a compromise, as if you ever found yourself without an E85 station, you could be in trouble unless you have a backup tune that really pulls a bunch of timing & boost.

I think being at higher elevation also helps the high CR from being as much of an issue.

Dave

 

It is not a daily driver and I never plan on running 93 and If I do I'll just turn the boost all the way down and drive off boost. That being said are there any other reasons than those.

 

Already did it a long time ago. Works but for most applications there is no reason.

Luke- https://www.evolutionm.net/forums/ev...-ix-turbo.html
Luke (again)- https://www.evolutionm.net/forums/ev...turbo-kit.html
Mikey- https://www.evolutionm.net/forums/ev...hp+stock+turbo (this one is actually 10.5;1 compression)

 

What are your thoughts on running low CR vs high CR on E85?

Say 8.5:1 vs 10:1

The lower compression would make more power on spool right? You can throw more timing in.. but up top it will loose out a little?

 

I am at 9:1 and dont seem to suffer. The 10:1 2.2 was a little slower than I am now so it definitely didnt help more than the displacement. As far as peak power, the old hot rod rule is 4% per FULL point. Its close but not exact in turbo cars from what I have seen. Assuming its not a knock restricted fuel (such as E85) we get closer. But then again thats equivalent to saying (if it holds true at all levels) that my 794 would be 825 if it was one full point higher. Running high boost on pump then becomes alot more restricted.

aaron

 

Wouldn't an engine intended to be run on alcohol only benefit from running even up to a 12:1 or higher? N/A race engines run on alcohol have been known to run up to 15:1.

I understand that you wouldn't be able to run on pump, but if you're going to run only alcohol it seems like you'd benefit from more compression. Is that need for more compression to maximize power on alcohol negated in a way by the turbo pressure?

 

We are talking about 2 different kinds of alcohol now.

Ethanol (ethyl alcohol or grain alcohol) is what E85 is composed of with 15% gasoline. What you are describing is Methanol (methyl alcohol or wood alcohol). Methanol has no upper end octane rating more or less from the tuning aspect. In practice it might have a RON and MON number, but it doesnt relate at all what you can in the real world.

Example- Luke's motor was at the edge of octane sustainability with 11:1 and 40psi of boost and keeping it happy. Chris Rado runs a 15:1 methanol motor and 86psi of Boost from a 95mm turbo, Brent Rau does something very similar. The real upper limit of what can be done on Ethanol has been pushed. We have run 12.5:1 and 25psi on our quads (cheaper to experiment on), there are a few 12:1 E85 motors either running or getting built, and then there are Methanol drag motors (one rally motor we helped consult and sell parts for) of course floating around as well.

 

This is why we need this guy.

 

im going to run 10:1 and i wouldn't go any higher.. 9:1 or 10:1 on e85..

 

Spool is strong, no apparent issues or drawbacks. It only makes real sense however if your turbo setup is efficient at 4+ bar, and everything engineered around that. Don't ask me how I know.


It may as well carry no octane rating because it just plain doesn't knock, and that raises some interesting tuning considerations.

 

Top alcohol runs static timing across the board and then tunes by EGT with fuel. MBT isnt a problem

 

Aaron thanks again for such excellent advice. I have decided on 10.5:1 . with all my mods I expected to be in the neighborhood of 440whp which will make quite a stock turbo beast!