Nix - I think that has to do with compression ratio, about 18:1 in diesels [around 600psi nowadays I believe] and the
fuel charge pressurestill hafta do the math Dave, and experimental observations as in the l1nk above to figure the "push" of the explosion, it's a thermodynamics thing

that's part of investigations for diesels by the makers, to improve fuel efficiency and reduce emmisions, especially Nox, which increases with temperature
Bill