[bobcowan]

If you're planning on using pump fuel, you can bump your dynamic compression up a bit, but don't go crazy. There's a lot of variability from pump to pump, and at different times of year. E85 may be anything from e80 to e90'ish.

The other issue is that they use some pretty cheap gasoline for the other 15%. It's really low octane unleaded stuff from the bottom of the tank. It can get up under the first ring land and detonate. It looks like a scene from "Alien". If Photobucket still worked, I'd show you a picture of that.

If you really want to go racing with high cylinder pressures, you'll need to use real e-85 race fuel. Otherwise, keep dynamic compression below about 8.5-9.0ish.