from:
http://e-85.com.au/878/ethanol-e85-racing-fuel/
For example, if gasoline is run at its preferred max power air fuel mixture of 12.5/1, it will release approximately 19,000 BTU’s of energy, where ethanol run at its preferred power stoichiometric of 6.5/1 will release approximately 24,400 BTU’s. By comparison, methanol releases slightly more, about 27,650 BTU’s. The more ethanol there is in gasoline, the more powerful it is as a motor fuel. Typically, you can expect at least 5% more horsepower at the rear wheels of a vehicle running on E-85 than one burning gasoline only.