If the compression of an engine is the only thing that determines the timing of an engine how does my old Saito 80 (the same model that Clarence Lee did a review on and measured the compression ration at 15:1) run at all? It also seems to love burning the high nitro fuels 15%+ too. I have also ran it quite lean with absolutely no knock (detonation, preignition). It has never once thrown a prop in the 15 years i've own it.

Fact: an engines combustion chamber shape and squish areas will play a big role in whether an engine will be prone to detonation or not. Look at the May "Fireball" head which allows a high compression engine to burn substantially leaner mixtures than the usually employed combustion chamber shapes.

I would say that an engines timing is a much more complicated affair than compression alone.