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Mixture is a major player in all this. Changing the mixture changes the speed of combustion (the speed of the flame front), as well as the temperature and pressure of combustion. For any given conditions, moving away from about 50 ROP in EITHER direction (rich or lean) will typically increase the margin from detonation. This does NOT mean that detonation can occur only at 50 ROP, only that it is most likely there.
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You can see this for yourself, for all the old radial charts show it, and both Lycoming and TCM produce charts that show CHT peaks at about 30 ROP, while maximum power occurs at about 80 ROP. The 15:1 ratio occurs, essentially at what we all know as our familiar "peak" EGT on our engine monitors.
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What this is telling me is that we are making a big mistake by disconnecting our 02 sensors and setting our mixtures richer than peak EGT with the idea that richer is cooler when just the opposite is happening. At 30 degrees rich of peak, cylinder head temps peak, moving richer to 50 degrees ROP is a danger zone for detonation, and richer yet you finally get max power at about 80 degrees ROP.
What a price to pay for a little more power, a risk of more detonation and abnormally high cylinder head temps.
Cheers,
Joe