Doubt CR is very high on a 2 stroker outboard running 1 cu in per hp. High compression engines have pre detonations or engine knock on timing advances (distributors had centrifugal advance weights) during acceleration as found in 4 stroker ignition systems of the point-coil days. Back in those days 12:1 had to have "Ethyl" high test whereby everybody running everyday cars got by on "Regular" running under 10:1 compression.
I had a '56 Buick Special 3 on the tree with a Hammer Head V8, plane jane, small block and Gulf Oil company had a purple premium fuel running just over 100 Research Octane when everything else was running 91 (all best I can recall).
I was just in the service (young and naive) trying to compete with my buddies and their 265 Chevy V8 hot dogs of the day with their short stroke and fast acceleration without much luck. The Buick hammerhead was either square or slightly under and the stroke was quite a bit longer and it couldn't wind up as fast.....but I thought the premium fuel would help.......it didn't. I didn't have a pre-ignition problem.
I had an '88 115 Direct Charge and I ran it on a 17' Ranger pad hull at 6000 rpms, pushing 50 mph (instrument) when wound out and it was on the cheapest gas at the pumps at the time.
