Quote:

Quote:

I did have one correction, with E90 the stoich A/F would be slightly lower than E85. A rough check:
Stoich Ethanol 9.0
Stoich Gasoline 14.7

E85: 0.85(9.0) + 0.15(14.7) = 7.65 + 2.21 = 9.8
E90: 0.90(9.0) + 0.10(14.7) = 8.10 + 1.47 = 9.6

Published numbers for E85 I have seen were 9.76. And I don't know if the stoich for the Maximal is different than 14.7 (maybe 14.5).

So, for max (safe) power, I would want to see richer than stoich, in the range I mentioned. And perhaps the dyno operator just has seen max power close to stoich on gas (but I would want to be richer to be safe). Use the cooling effect of the ethanol and put more fuel to it. But that may only be a secondary issue with the rings, not the prime cause.

Good luck.


I may have too much cylinder pressure as a result of the cam having 112 lobe center. I am staying away from the ethanol on this engine, and staying with race gas to be safe. But on my next build, I think I'll try to build one specifically for the E85 and match the camshaft specs to that combo. Do you have any idea about what effect mixing leaded race gas with ethanol has? Some people on this thread say it doesn't raise the octane level like you would expect, and that would account for the detonation.



I copied this from a thread on Innocate's forum:

“You guys need to know that the metallic additives used to raise the octane of gasoline lower the octane of the alcohols. TEL, TML, and MMT are pro-knock in behavior with methanol and ethanol and probably the other alcohols as well. I don’t know for a fact, but I strongly suspect, that MMT is significantly pro-knock in alcohols. I’ve seen and been told of engine wrecks that I know had methanol and MMT involved (and TEL in one).

In Obert’s book he shows the R/M octane numbers of methanol as 106/92 and ethanol as 107/89. The addition of 3ml TEL per gallon of ethanol lowers the 107 to 102. You decide what this means to you when you mix leaded race fuel with alcohol.

The octane behavior of alcohols, like any fuel except pure isooctane, is affected by the AFR. Leaner AFR = lower octane behavior. Good race fuels have well over 100-octane behavior at the worst possible AFR conditions for knock. The alcohols obviously have very low octane behavior at lean AFR’s”


One man's point of view on mixing leaded fuel with Ethanol. Hope this might help explain or get you pointed in the right direction.

Disclaimer: I found this on the internet, so take it with a grain of salt!!