Getting back to the acetone discussion . . . I see what you're saying somewhat, Sunder: gasoline blends with lower octane ratings can allow fuel-air mixture to combust during compression prior to the spark plug ignition in lower compression engines. But I am sticking to the concept that the energy release during combustion/oxidation can be called an explosion; it's these hot gases that result from the destruction of these moderately long carbon molecules that drive the piston back out of the combustion chamber.

94 YJ, SOA, 2-1/2 Alcans, ARB-front, Detroit-Rear, 4.56:1 gears, Oasis Trailhead compressor, 4:1 Terra Lo, 37x12.50x15 SSR's, 8000 lb Ramsey, & etc.