OK thanks Steph.

I am thinking this might be worth a try as long as the fuel system compatibility is OK. I am thinking as a first cut for tuning, I could scale the whole fuel map (richer) by the stoich AFR ratios between gas and E85, which is roughly 50% IIRC. That is easy to do in Megatune. Then after that, do the usual WBO2 based log/tune/log/tune testing to fine tune the fuel map based on target AFRs for E85. Then, after that, play around with advancing the timing while watching/listening for knock.