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The whole topic of "quench" give me hives. The name is all wrong, it was called that by someone who didn't understand what it really does.

The subject is properly called SQUISH. That's what Sir Harry Ricardo called it when he developed it and actually patented the idea back around 1919.

If you understand about flame travel it'll help. If the mixture isn't moving around much, the actual flame travel is on the same order of magnitude as piston speed. That's slow. While the slow burn is heating the contents of the combustion chamber, the fuel in the farthest out places is turning into compounds that self-ignite much more easily than the original fuel. So how to get the mixture to burn quicker?

By bringing two surfaces together very closely, a high speed jet is expelled and physically mixes the flame through the chamber. Thus the burn completes faster than the knocking compounds can form.

So the good idea is speeding up the burn. The wrong idea is that somehow the surfaces are "quenching" the knock. But it is the speed that the burn is completed that makes the difference.

If one could get the piston to come within 0.001" of the head every single time it would be better.
Check out www.theoldone.com for more.

R.

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So with this explanation, does that also mean because of a "faster burn", timing can be dialed back?

I was mentioning to 383 last night a question about thermal coatings interfering with the heat absorption based on the earlier explanation of the nearby surfaces cooling the fuel air mixture preventing pre ignition. Seems to me if coating reject heat from being absorbed by the piston, etc, the coating would also retard heat being absobed from the mixture.