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Thread: Ls1 cr

  1. #1
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    Ls1 cr

    Just curious here, but what heads would one use to get about 9.5:1 CR on an LS1? 317's maybe? And what is the stock CR on an LS1?

    ~ Forged engine of some type ~ Ball bearing turbo of an unconfirmed size ~ 4L8000 trans ~ Beefy fuel system ~

  2. #2
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    Quote Originally Posted by jetmech View Post
    Just curious here, but what heads would one use to get about 9.5:1 CR on an LS1? 317's maybe? And what is the stock CR on an LS1?
    I am going to save all of us a lot of trouble. Here is a compression calculator. Google can answer any questions you have about the information it asks for.

    http://www.csgnetwork.com/compcalc.html

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


  3. #3
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    Quote Originally Posted by pl4yboy View Post
    I am going to save all of us a lot of trouble. Here is a compression calculator. Google can answer any questions you have about the information it asks for.

    http://www.csgnetwork.com/compcalc.html
    Thanks pl4yboy.
    "ALisSa1 Silverado"
    1990 Chevrolet RCSB 2002 Chevrolet Camaro LS1/4L60E
    Scrimpin Ain't Easy
    ( . Y . )


  4. #4
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    LS1 and 317 head with stock 6.0 gasket give you 9.2cr. That was my old set-up.
    Truck 2002 Chevy with
    old setup KB turbo kit MP70 LS1
    New setup stock for now

  5. #5
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    what are the stock values for that calculator playboy?
    blown transmissions are about as useful as 97% of the guys on this forum

  6. #6
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    Quote Originally Posted by aaronr View Post
    LS1 and 317 head with stock 6.0 gasket give you 9.2cr. That was my old set-up.
    Now that's the kind of answer I was looking for. Thanks dude. BTW, which heads will get an LS1's CR a little higher than 9.2?

    ~ Forged engine of some type ~ Ball bearing turbo of an unconfirmed size ~ 4L8000 trans ~ Beefy fuel system ~

  7. #7
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    Quote Originally Posted by jetmech View Post
    Now that's the kind of answer I was looking for. Thanks dude. BTW, which heads will get an LS1's CR a little higher than 9.2?
    I posted a calculator for a reason. Don't be lazy, you have the tools right in front of you.

    By the way, LS1 with 243s is 10ish. If 317s are 9.2, there is not really anything in between that is worth a damn. You can have the 317s milled to raise compression.

    1969 Chevy RCLB C10 350/TH400 SOLD
    2007 Chevy RCSB 4.8 4x4 LS SOLD
    2008 Chevy RCSB 5.3 4x4 LT SOLD
    2010 Chevy CCSB 6.2 4x4 LT SOLD
    2005 GMC CCLB DRW 6.6 Duramax 4x4 191,000 and counting
    2013 FORD CCSB F350 6.7 Powerstroke 4x4


  8. #8
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    Quote Originally Posted by pl4yboy View Post
    I posted a calculator for a reason. Don't be lazy, you have the tools right in front of you.
    I'm still looking for the rest of the info the calculator calls for.

    ~ Forged engine of some type ~ Ball bearing turbo of an unconfirmed size ~ 4L8000 trans ~ Beefy fuel system ~

  9. #9
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    you can play around with the gasket thickness and milling to get the exact CR that you want.

    old mod list: H/C/I/N/E/G 408
    new mod list: 5.3, gears/posi, mufler and tune : (

  10. #10
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    Quote Originally Posted by TXsilverado View Post
    you can play around with the gasket thickness and milling to get the exact CR that you want.
    True. While I don't mind using different thickness gaskets, I'd like to avoid milling heads because I don't want to have to get different length pushrods.

    ~ Forged engine of some type ~ Ball bearing turbo of an unconfirmed size ~ 4L8000 trans ~ Beefy fuel system ~

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