Originally posted by Stu Cool
I would be interested in an explanation of the difference between the two

Pat
Hmm, actually, in this context there isn't any real difference, I misspoke, I was thinking about pre-ignition.

That being said, spark knock is the result of detonation, it is the sound of the fuel/air mixture exploding (instead of burning) and echoing off the cylinder walls, piston and combustion chamber.

Once the burn goes supersonic it is detonated so it's a matter of burn rate and the myriad of materials, geometries and processes that affect that aspect of the combustion process.