For high performance use, E85 (up to 85% ethanol) is poor mans race gas at appx 105 octane.

You can make serious power running E85 especially in forced induction applications.
I would clarify that this is when building an engine and writing a custom tune (if an ECM controlled engine) but would not be the results in a "street" engine thats designed for typical pump gas and E10. You would not want to run E85 unless you have a "flex fuel" vehicle and would not get a boost in performance running E85. Hell, I have a flex fuel tahoe and WILL NOT run E85. Corn is meant for whiskey not my gas tank.