[J4nn3R]

So far this is just theoretical, I don't think that I'm going to have budget, time or place to do anything concrete any time in near future, but I'd like to know if I'm after something. There is so much technical knowledge here, that someone got to know or have a relevant argument's at least.

This hypohesis is mainly for ethanol fuel, I think. As we know, ethanol's energy content is lower than petrol. But, because of that it burns a bit cooler. It have a higher octane number too, so it's possible to use higher compression ratios.

So, if a engine running with ethanol is turbocharged with relatively low pressure, let say 7-8psi/0.5bar and no cooling is used, we have a warmer intake air, better fill in cylinder and part of the wasted energy in exhaust gasses is used to produce power, is it going to be better average mpg?

Most of the small modern engines have turbo, but that's maybe mainly to have efficiency benefits of small engine but the power of a bit bigger engine, to make customers happy? But is it possible to charge an engine only to use lesser fuel? Or has it got to be done with longer gear ratios to have any benefits?