[rattlesnakepete]

I believe there are two forms in which combusion can physically occur, 1) weak defligration and 2) strong detonation.

In defligration the preheat comes from radiation/conduction of the previously combusted material. Almost all forms of combustion common to us are weak defligrations, even including the discharge of a firearm cartridge.

In detonation the preheat comes from a propagating shock wave and not radiation or conduction. Detonations involve very large magnitude pressures, millions of psi. It is ubiquitous to use the term detonation in context with I/C engines but I believe it is technically incorrect.

In interesting subject and thread nontheless.