Engine Compression

**TransAm** · 03-26-2010, 05:30 PM

confused on what compression to build my motor. Some people say nothing over 8:1, some say get a little more horse power out of the motor and go 9.5:1. I have a D1sc ProCharger, set at 14lb of boost. Dont know alot about the system and this is the first time on this form. Thanks for any help I can get

**444** · 05-31-2010, 09:51 PM

I don't claim to know it all on this subject, but seeing as how boost artificially increases compression I don't see why you would want to lower one to increase the other. I'm setting mine up for 10:1 compression but with meth injection to keep detonation at bay. I would say it will also depend a lot on whether you're running iron or aluminum heads as well as combustion chamber design/efficiency/quench.

**DART340SC** · 06-02-2010, 05:32 AM

I run a stroked small block mopar (406ci) with a engine comp. of 9-1 and run 14lbs boost. I am also running a air to air intercooler and methanol injection. I have no detonation. I do know that it is a proven fact that a lower comp. motor running more boost will make more power than a higher comp. engine running less boost, also more reliable.

**TransAm** · 06-02-2010, 09:27 AM

Dart.
Thanks for the reply, That helps. I'm building a 383 stroker 9-1 14lbs boost. No intercooler or methanol

**69fury** · 06-20-2010, 01:36 PM

9:1 at 14lbs of boost has the net effect of a non boosted engine at 14.8:1 compression ratio, so you're gonna need to do something.

Planning on running corn or race gas?

-rick