im buildin a very beefy 350. i want POWER!!! whats the best CR to aim at? i was thinkin anywhere from 13.1 - 10.1??? its a street/strip engine! ill be usin 91 octane pump gas

 

Lots of variables in that.

 

We have an understatement here


David

 

If TMI = Too Much Information and TLI = Too Little Information, this definitely is TLI. You really need to priovide LOTS of details before this can be intelligently discussed. Before even starting the discussion, I suggest you do a search of "dynamic compression ratio".

Very, very briefly: for a given set of conditions the later the intake valve closing point the more compression you can use without detonation. And (also very oversimplified) you should use as much compression as you can as long as there is no detonation. For a high-performance 350 running pump fuel, this can vary from as low as ~7.5:1 for a forced induction motor to ~12.5:1 with a NA setup and a big cam. Obviously, if race gas is used along with a huge cam, CR may be much higher - as high as ~17:1. Above ~17:1 there are some serious problems, so few combos run more than that sucessfully (unless they are diesels!).

Rich