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Thread: Engine Compression

  1. #1
    Junior SCH Member
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    Mar 2010
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    3

    Engine Compression

    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

  2. #2
    Junior SCH Member
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    Apr 2009
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    36
    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.

  3. #3
    Junior SCH Member
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    Apr 2010
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    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.

  4. #4
    Junior SCH Member
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    Mar 2010
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    Dart.
    Thanks for the reply, That helps. I'm building a 383 stroker 9-1 14lbs boost. No intercooler or methanol

  5. #5
    SCH Member
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    Nov 2009
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    Lawrence, KS
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    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

  6. #6
    SCH Member
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    Nov 2009
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    Lawrence, KS
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    http://victorylibrary.com/mopar/blower-engine5.htm

    scroll down to the big charts......

  7. #7
    Junior SCH Member SScott's Avatar
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    Jul 2010
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    Alabama
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    Some great info here. Thanks everyone.
    "The older I get, the more I realize how little I knew when I knew it all."

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