(Disclaimer: I'm not an engineer or an expert. Just a fiction writer. But this is what I've been told.)[/QUOTE]
Jack, Somehow I find a dash of humor in your disclaimer.
Lower octane fuels burn Faster than higher octane fuel.
To offer a visual explanation, if you had a glass tube and put a couple of drops of lower grade fuel inside, shake to atomize the fuel and ignite one end, you would see the flame front travel or flash to the end opposite end of the tube. Explode if you will. Now, same exercise with higher octane fuel will show a slow, smooth flame front that gently travels the length of the tube.
Octane retards the burn, which actually results in a cooler combustion temperature. Compression also contributes to detonation combined with the higher cylinder temps generated with low octane much like a diesel engine operates.
(Disclaimer: WHAT JACK SAID)