[Stan Weiss]

Originally Posted by Formulajones

Just for giggles, and I'm sure someone here may know the answer.

There are formulas available to plug numbers in and figure your dynamic compression, which is useful for figuring octane requirements.

Off the top of my head, a 9.7:1 455 with the RAIV camshaft will probably have a dynamic compression of somewhere in the mid 7's which is easily safe on pump gas (camshaft install position plays a roll) If it started to get up in the lower 9's for dynamic it starts to become a problem.

Cranking compression can be another clue.

X2. But remember cranking compression on the same engine will vary. It is less in Denver than it is at sea level.

Stan