[soutthpaw]

I was not trying to compare E85 to regular gasoline...What I was getting at was that you could have a more advanced timing and probably a longer injector "on" time to dump more fuel in the engine due to the Air/Fuel ration that E85 can burn at thus giving more power than running E85 on the factory stock settings. (this would probably negate any $$ savings compared to gasoline as it would use more e85 than the stock tune) As far as i am aware the engine cannot tell the pecentage of E85 vs gasoline in the fuel tank to make changes.. thus it would need to be done manually.. So from that perspective an E85 tune would be a great idea. Also, unless you run it exclusively or drain your fuel tank before filling you probably are running a mixture more like E50 or E60 for example.
I was not trying to compare E85 to regular gasoline... as I mentioned before I am aware of and pointed out that Octane only inhibits combustion.