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LS3 Head Milling Questions

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Old Jan 26, 2016 | 02:15 PM
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Jarren_b's Avatar
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Default LS3 Head Milling Questions

Couple questions guys.

1. If you were to put a stock ls3 head (69.6CC) on an LS2, what would the compression ration be?

2. approximately how much would you have to mill off the same head to get it to 66cc?

Im trying to calculate my new compression ration after buying some heads

I bought used PRC LS3 heads that I was told were milled to 66cc. I then milled .004 off them to make sure they were flat.
Im using GM MLS headgaskets that are .051 compressed with a 4.080 gasket bore

I know that my stock ls2 compression was 10:9.1 with 64.45 CC 243 heads

Let me know what you guys think
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Old Jan 26, 2016 | 03:11 PM
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Originally Posted by Jarren_b
........If you were to put a stock ls3 head (69.6CC) on an LS2, what would the compression ration be?.............I know that my stock ls2 compression was 10:9.1 with 64.45 CC 243 heads.......
Jarren........Just a SWAG but I'd say about 10.3:1......

If you know the FULL specs of the LS2 engine (short block) you can Google up a Compression Ratio Calculator to get the correct/exact figure .

KW
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Old Jan 27, 2016 | 12:07 AM
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If heads are off just measure the cc
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Old Jan 31, 2016 | 07:43 AM
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Milling .006 off the head will get you 1cc.
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Old Feb 9, 2016 | 10:11 PM
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Originally Posted by Lead-head
Milling .006 off the head will get you 1cc.
That's correct, let me add mill .050 put them back and go check out your smile.
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