Some info from EB on Detonation for those interested:
"*Morning!

Detonation is a completely different thing from pinging, although typically
both can exhibit and pinging can lead to detonation. The other way around
cannot happen because of the cycle of when each occurs.

.Pinging is when the fuel and air are set off early, or when a hot spot in a
cylinder ignites the mixture along with the spark plug also setting it off.

The result is two flame fronts colliding, this noise is the crackling sound
we hear. The mass of metal surrounding dampens the noise, so it sounds a
bit like some marbles rattling in a tin can inside the engine.

Detonation happens after top dead center, the mixture reaches the
distillation point all at once instead of vapor layers igniting in a gradual
curve at the cylinder heats up.

Since it happens after top dead center and all of the fuel and air ignites
at once, there is no sound. There is only extreme pressure created. Well,
sometimes a sound, normally with the big cloud of smoke followed by
silence....*LOL**..

It is extremely rare for a street engine to go into detonation, this is
because we are on and off the throttle. When off the throttle, the cylinder
purges and the temperature drops, detonation stops. So we see the results
of detonation in racing engines held at full throttle, and this happens
typically below torque peak. The engine in this situation will never
recover from the detonation situation unless the throttle is lifted, then
recovery is instant.

We also see the results of detonation with engines used for hauling or heavy
loads, long pulls uphill using full or close to full throttle.

The result? Something breaks, and this is almost without fail.

Pinging can be present and not create a lot of sound. A sharp spot in the
cylinder, some carbon buildup that is glowing and igniting the mixture out
of time, tuning errors, etc. This creates heat, the damage will be
particles of aluminum pulled out of the piston head, the color of the
underhead of the piston will be a dark chocolate or black, and rings can
over heat and fail in time. Actual detonation looks similar.

It is far more likely you had a cylinder or more running too hot, this would
fail the rings.

What you didn't have...is "detonation." Just my opinon from your
description. This doesn't mean they are not telling you the truth, the term
"detonation" has become a catchall phrase for meaning, '"Piston got too
hot."

I hear it every day from very good techs who don't really have a complete
understanding of what it is.

Hope that helps, sorry, didn't mean to write an article, but it is a
complicated subject. You may post this if you like, it might help someone
else to understand.
Ted"