This means if you were to run E85 in an 11:1 or 12:1 compression engine, E85's higher octane would prevent detonation, which would allow you to run this higher compression ratio and take more advantage of the reduced Btu heat output by squeezing the existing air and fuel a little harder to make more power.

Is E85 good for high compression motors?

Plus, E85 reduces inlet air temperatures which improves power by cooling the air entering the cylinder. Cooler air is denser, which adds power. There will be significant tuning changes necessary when using E85 instead of gasoline, but high-compression engines can especially benefit from E85.

At what compression ratio do you need E85?

According to Wusz, even given the cooling effect of E85, his recommendation would be to limit the static compression ratio to 13:1 on a 4.00-inch bore small block and slightly lower in a larger bore engine like a big block Chevy.