cut and copied from every E-85 thread I read.
"I posted this deep in a BS thread and would like it to get more light that it did. For those of you that have access to this stuff give it a shot! Ethanol burns cooler which is great and all, but when you toss some more timing to the mixture it becomes great!!
Hell at the least it is a cheap race gas (locally about 2.50). I would run up to a 13.5 compression piston with out any problems. I had my predator with 12.5 compression piston tuned for it (yes you HAVE to tune for it) and it ran amazing!!! The exhaust smelled pretty cool. Kinda like vodka. I talked to my dyno guy and he said that you can have two maps made for your bike. One for gas, and the other for E-85 and switch maps on the PC3 on a handlebar mounted switch. If you ever have to run other fuels this would be great.
E85 is 105 Octane, and requires you to much much richer than gasoline.
Theres a few differences you'll have to note:
E85 has a lower energy content that gasoline. This means less power per gallon. 1 gallon of gasoline contains 114,132 BTU. 1 gallon on ethanol contains 76,000 BTU. 1 gallon of E85 has roughly 83,263 BTU. MOST E85 isn't a straight mix of ethanol/gasoline. Its 85% denatured alcohol (~95% ethanol, ~5% gasoline). Thats 27% less energy.
Another thing is the A/F ratios for E85. The Stoichiometric ratio of Gasoline is 14.7:1, while it makes max power around 12.5:1. E85 has a stoichiometric ratio of between 9.73:1 and 9.8:1 (based on pureness), while max power is made as rich as 7:1, although recommended around 8:1.
So, less power, and richer A/F mixtures? Not exactly. Consider the BTU/gallon vs. the A/F ratio required to run E85.
Compare the stiochiometric ratios of the two. Gasoline is 14.7:1, while E85 is 9.8:1. I think my math is a little off on this but thats 50% more fuel. 1.5 (150%) x 76,000 = 124,000 BTU. Thats slightly higher than the power produced by a gallon of gasoline. Now take the max power rich A/F ratio of gasoline and E85. Gasoline is 12.5:1, while E85 is about 7:1. Thats about 78.5% more fuel than gasoline. 1.785 (178.5%) x 76,000 ~ 148,000 BTU. Thats roughly 29% more power than gasoline!
What else does this mean? Just by switching from gasoline to E85 and adjusting it to the max power rich A/F ratio in your turbocharged engine, you could pick up roughly 15% power. Another thing to consider it the octane of E85. Its 105. Think about running 105 octane gasoline in your car with a 7:1 A/F ratio. Detonation? Probably none. This means you can severly raise boost or advance your spark for higher power and not have to worry about detonation.
Another thing to consider. E85 is about as cheap as 89 octane gasoline, which is even cheaper than the 93 most SRT guys run. The only downside is that you'll probably see roughly a 25% decrease in MPG if you adjust the A/F ratios to run at the stoichiometric ratio of the E85 (you still won't have to worry about detonation at this ratio). With the increasing gas prices and the ever decreasing ethanol prices (it IS a renewable resource), in the years to come it may become cheaper to run on E85 than gasoline. "
