From my research, E-85 should make more power as long as the fuel system can deliver the extra amount of fuel needed.
The E85 BTU is lower than Gasoline, but you burn more of it with the same amount of air, so you end up with more BTU per unit of air. It looks like maybe around 5% more power on E-85 (I need to re-run my calculations, the original ones I did showed 3.3%, but I used a too low a BTU rating for the E85.)
Here is what I was looking at:
1 pound of air will burn 1/(air/Fuel ratio) to get amount of fuel. So 1/14.7 = 0.06803 pounds of gasoline, and 1/9.7 = 0.10309 pounds of E85. Using 6.2 pounds/gallon for gasoline, and 6.59 pounds/gallon for E85, this equates to 0.421769 gallon of gasoline, and 0.679381 gallon of E85.
Using 116,090 BTU/gallon for gasoline, and 85,000 BTU/Gallon of E85 (E85 varies in BTU depending on the blend, but the ranges given are between 73% and 83% of gasoline?) So the 85,000 value is near the low end.
Multiplying the amount of fuel in gallons burnt by one pound of air by the BTU per gallon results in:
Gasoline = 48,963 BTU per pound of air.
E85 = 57,747 BTU per pound of air.
This probably is not the correct way to do the conversions, but it makes some sense to me.
From the Stoichiometry wiki page:
https://en.wikipedia.org/wiki/StoichiometryPercent of fuel by mass:
Gasoline = 6.8%
Ethanol (E100) = 11.1%
