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    Author Topic: compression ratio  (Read 765 times)

    Offline BIG MIKE

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    compression ratio
    « on: May 13, 2008 - 10:09:16 PM »
    what would be the best for street/strip....i always heard 10 to 10.5..
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    Offline 73Chally

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    Re: compression ratio
    « Reply #1 on: May 13, 2008 - 10:12:36 PM »
    10.5 would probably be about right.  Maybe 11 if you have good cooling.
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    Offline The Cuda Guy

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    Re: compression ratio
    « Reply #2 on: May 13, 2008 - 10:19:26 PM »
    Quote from: 73Chally on May 13, 2008 - 10:12:36 PM
    10.5 would probably be about right.  Maybe 11 if you have good cooling.

     :iagree:
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    Offline 72hemi

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    Re: compression ratio
    « Reply #3 on: May 13, 2008 - 10:19:54 PM »
    Whether you are running iron or aluminum heads makes a difference. The general rule of thumb is you can run 1 point higher compression with aluminum heads. I am running 10.5:1 on my 440 with iron heads. A friend of mine with aluminum heads is running 11.7:1 ratio.
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    Offline BIG MIKE

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    Re: compression ratio
    « Reply #4 on: May 13, 2008 - 10:24:42 PM »
    i heard that about alum. heads..i was talking about iron
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    Offline Chryco Psycho

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    Re: compression ratio
    « Reply #5 on: May 14, 2008 - 02:08:23 AM »
    Maybe we have crap gas for $5 / gallon but I seem to have to stay under 10:1 with iron heads
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    Offline moper

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    Re: compression ratio
    « Reply #6 on: May 14, 2008 - 12:13:54 PM »
    There is no perfect one for every setup. Each setup has it's perfect one. Dont worry aboutt eh static ratio. It's irrelevant now. Use teh dynamic ratio, which takes ionto account the rod ratio and camshaft. Stay below 8.25:1 dynamic, and it wont ping when set properly. Aluminum I run between 8.5 and 8.75:1. With a long stroke and small cam that means the static number will be lower. With a shorter stroke and bigger cam that cam be much higher. the 440 I have for sale is 10.8:1 with open chamber irons, but the dynamic ratio is 8.3:1. Well within 89 octane w/10% ethanol. The 422 just delivered has a smaller cam, so the static is 9.5:1.
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