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Thread: Compression Ratio with pump gas??

  1. #1
    Senior Member MASTER BUILDER
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    Apr 2009
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    175

    Compression Ratio with pump gas??

    What is the max comp. ratio if I still wanna run pump gas??

  2. #2
    Senior Member RACING JUNKIE
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    I have ran 11 to 1 with premium gas with no issues. Most will tell you that's too much and maybe it is...but I got away with it.

  3. #3
    I am the same as TOD running 11.0 to 1, but 10.5 is a safe number to shoot for.

  4. #4
    Junior Member JOURNEYMAN
    Join Date
    Jan 2005
    Posts
    26

    compression ratio-pump gas

    I have a 355 sbc with 10.5 flat tops. It previously detonated when I ran some old steel 64cc turbo Chevy heads, #340292. We replaced them with a set of 68cc AFR alum heads with 180 runners and the detonation went away. I don't know if it was more from the larger chambers or the alum head material, but I suspect it was more from the aluminum since it dissipates heat better. It's may be easier and cheaper to swap heads than pistons. JMO Mep

  5. #5
    Senior Member RACING JUNKIE
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    let me rephrase...mine was 11 to 1 on paper, I never measured anything and did the math. It was a flat top piston 406 with 5.7 rods and it had a small hyd cam .507 lift dur @ .050 was about 244 I think. It had a set of the original sportsman cast iron heads with 64 cc chambers( advertised I didn't measure them)

  6. #6
    Senior Member MASTER BUILDER
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    is there any way to measure comp. ratio with the engine in the car???

  7. #7
    Senior Member RACING JUNKIE
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    Quote Originally Posted by whitey70ss
    is there any way to measure comp. ratio with the engine in the car???
    NO

  8. #8
    Senior Member RACING JUNKIE
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    Jul 2007
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    Independence, Missouri
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    Oh, Boy :!: :lol:
    No matter where you go, there you are.
    **IN GOD WE TRUST**

  9. #9
    Senior Member RACING JUNKIE
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    are we going to use that magical compression guage again!! :lol: :lol:

  10. #10
    Senior Member RACING JUNKIE
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    4,143
    Quote Originally Posted by MEMRACING62
    are we going to use that magical compression guage again!! :lol: :lol:
    I almost went there but decided against it...lol


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