The detonation margin is pretty good with the 7.5:1 CR. That's why they did it.

A large part of the detonation margin is CHT. Cars use a water-cooled engine that keeps CHTs very cool. It doesn't always work too well. The ping we've all heard is detonation. Remember those are seldom aluminum heads! Also, detonation isn't all that bad on the engine. It's very hard on spark plugs which are a source of pre-ignition which is VERY bad on an engine.

Walter


On May 12, 2005, at 2:09 PM, colyncase on earthlink wrote:

Walter,  so how narrow is it on a TSIO-550 with 7.5 CR?
How is that cars can run 10.0 CR?