Quote:
Originally Posted by serialk11r
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.
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The form of fuel injection does not raise its octane rating because octane is its chemical resistance to detonation. Direct fuel injection of ethanol is more like mechanical resistance (not sure if I am explaining right so feel free to correct me). However you are completely correct in regards to significance.
Ford built such an engine, a 5.0 v8 if memory serves. They were able to get something like 1200 hp at 45 lbs. of boost (again from questionable memory) on pump gas. Of course, one cylinder of that engine could drive a standard size passenger car easily with a more advanced valve train and the lower friction. This is ethanol's future, as a supplementary fuel in a dual fuel setup. If you want bio fuel for an Otto cycle engine, make butanol.