I think it's fair to say that increasing compression creates a lot of mechanical resistance just to turn over an engine. THAT having been said - is the amount of energy liberated significantly higher so as to overcome the added mechanical loss?

How would that be figured... Cumulative mechanical resistance to engine turnover vice overall resulting power divided into eachother for the net efficiency?

How efficient is a deisel? (300 PSI compression) This sounds kind of similar.