Quote: I am staying away from the ethanol on this engine
Have you tried richer mixtures in the carb on your other "E85" engine?
I did and it slowed down. All I did was took the carb off the old motor with the tune up that worked all year, and put it on the new one on the dyno. Also used the same fuel I used all year. So that is the weird thing, that it detonated.
