"J. Clarke" wrote in
:

Since the mention of Offenhausers was in the
context of power per cubic inch on pump gasoline
and the example used was an Offy with 15:1
compression it's very relevant that the example
did not run on pump gas.

OK, I must have missed that post. Anyway, yeah, the Offy
was usually 12:1 or 15:1 on methanol, since you can run
it real rich and there's no risk of detonation. Unless
it was a turbo motor, in which case the static compression
was much less (because the turbo more than makes up for it).

But then, no gasoline engine will run 15:1 compression
at full throttle on pump gas. You have to have some
trickery to change the effective compression ratio,
lower for full throttle/full power, higher for part
throttle/economy. Or run 110 octane pump gas, and plan
on fairly frequent rebuilds (some drag racers run that
high). On pump gas, 12:1 is about the max.

John