Quote:
Originally Posted by TheEnemy
I think 100% ethanol has an octane that is something like 110.
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I think it depends on delivery. When direct injected strategically to provide maximum cooling effect before ignition, it could be even higher (much much higher), and the efficiency will improve because you are using some of the cooling effect to reduce work required for compression rather than allowing the heat of combustion to provide the necessary heat for evaporation. Done correctly I think I read that you can get better mpg for certain blends despite the lower heat energy in the ethanol fuel.
I believe there is an MIT study where they were able to get the "equivalent" of 150 octane by injecting E85, and supplementing with 87 via port injection.