[dangerdoc]

The higher octane level in Etoh would allow an ethanol fueled engine to run at diesel compression levels allowing an engine that runs at about 40% effiency rather than 30% of typical gasoline engines. It would require an engine redesign with beefier components but not really any different than the engineering required for diesel.

Going from 30% to 40% is about a 30% improvement in effiency which would largely mitigate the lower energetics of the fuel.

Other than disagreeing with me, do you have a point to make?

[thackney]

Other than disagreeing with me, do you have a point to make?

Yes. Increasing compression will NOT make an increase in MPG that you are implying. Many other inefficiencies within an automobile make up the total.

Are you going to reject less ratio of heat to delivered power? Decrease friction? But you will increase weight with a stronger engine to handle the increased pressures.

High compression engines are not new, and they are used in performance vehicles, not low MPG vehicles.

If your claim was true, why doesn't diesel vehicles, using a fuel with an energy content ~60% more than ethanol, have more than double the MPG of gasoline vehicles?