Causes of detonation?

moper said

Pinging is not the same as detonation. Pinging is caused by heat in the chambers, or lower octane. I asked for timing curve info and the condition of the heads because oil coming down guides can also make an engine ping even on higher octance fuel. What are your cylinder pressures?

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True about the possibility of oil causing it.....but I always considered pinging and detonation as the same thing, whatever the causes.

Knocking (also called knock, detonation, spark knock or pinging) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. It should not be confused with pre-ignition (or preignition), as they are two separate events.

http://en.wikipedia.org/wiki/Engine_knocking