I have been searching for hours and have conflicting data. Basically if engine A has 18:1 CR and 0psi boost and engine B has 13:1 CR and 8.5psi boost, the pressure at TDC-Compression is the same or rather the "effective CR" is the same. However, engine A is 16.7% hotter at TDC but has 43.7% less moles of air. On gasser forums they seem to concur that effective CR is the ticket. On diesel forums they concur that moles of air (density) that gets into the combustion chamber is the ticket. Being that fuel needs air to burn and that there is a 43.7% difference in the amount of air between the two, I would think engine B would have much more power. I realize the higher CR means it needs less boost because the energy density being in such a small area gives it a kick in efficiency that does the same as low compression high boost. But what is the truth? Thanks for any help guys.