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Thread: wrong combo???

  1. #1
    Junior Member SHOW GUEST
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    wrong combo???

    My 454 bbc has 11 to1 closed chamberd pistons and square port open chamberd heads (990 casting).Is this really hurting my HP or should i go after closed heads?I race this engine and turn mid 11s in a 3500# monte ss.Trying not to break the bank on a total rebuild because engine has low miles on it.Thanks gene.

  2. #2
    Senior Member RACING JUNKIE
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    IMO, you are losing atleast 2 points in the compression, with the open chamber heads. I think the easiest way out would be to change to some 13.1 open chamber pistons. i don't know how much you would pick up but i would think close to 2 to 3ths. ofcourse you would have to rebalance the engine with these changes.

    JMO

    Zip.

  3. #3
    Senior Member RACING JUNKIE
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    Quote Originally Posted by zipper06
    IMO, you are losing atleast 2 points in the compression, with the open chamber heads. I think the easiest way out would be to change to some 13.1 open chamber pistons. i don't know how much you would pick up but i would think close to 2 to 3ths. ofcourse you would have to rebalance the engine with these changes.

    JMO

    Zip.
    I second that>
    ***IN GOD WE TRUST***

  4. #4
    Senior Member RACING JUNKIE
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    I 3rd that.
    You want to keep the open chambers , they are a better head in my opinion.

  5. #5
    Senior Member RACING JUNKIE
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    I 4th that, keep head, more compression on piston.

  6. #6
    Junior Member SHOW GUEST
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    well i think im going to get BIG PISTONS Thanks guys.I also thought that these heads were better.

  7. #7
    Member JOURNEYMAN
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    You have ~9:1, your set up is exactly what GM did to the '71 LS-6 454. It lost 25HP and a little more TQ.
    "Good people sleep peacefully in their beds at night, only because rough men stand ready to do violence on their behalf."

  8. #8
    Senior Member RACING JUNKIE
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    Just jerk the top end off and put a set of aluminum heads on that baby. Thats easier than pulling the engine out and apart and the additional cost may weight out after you consider all the additional time you spend tearing her down.


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