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Help with calculating skim amount to raise compression?

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Old 09-06-2013, 04:02 PM
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Default Help with calculating skim amount to raise compression?

Can anybody please offer any advice as to how to calculate the amount required to raise compression?

I have a 5.3 L33 which as standard has 9.9:1

I have the heads off and want to get the head skimmed to ensure it is flat before refitting and figured that rather than just remove the bare minimum I could remove a specific amount to raise the compression.

Ultimately I would like to increase it to around 10.2:1

The heads are still standard so I figure the heads measurement should be known (combustion chamber), and I presume I would therefore just need to know the head gasket thickness in order to calculate the required amount of material removal.

???
Old 09-06-2013, 05:47 PM
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Each .006 mill is about 1cc
Old 09-06-2013, 06:11 PM
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Originally Posted by PREDATOR-Z
Each .006 mill is about 1cc
Many thanks for the reply.

How do I use that information to calculate a new compression ratio increase?

I haven't found a definitive answer to the question of the 799 5.3 head CC but it appears to be around 64.

Last edited by TableLeg; 09-06-2013 at 06:18 PM.
Old 09-07-2013, 03:57 AM
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OK, so using this calculator I 'think' I've come up with the necessary figures to calculate the compression ratio (assuming all the details I found on the internet are correct!).

http://www.gtsparkplugs.com/CompRatioCalc.html

From this it would appear that 0.020 removed from the heads should equate to 10.37:1

0.010 should equal 10.13:1

0.015 should equal 10.25:1

Any body know if this sounds about right?
Old 09-09-2013, 01:23 AM
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Anybody know if that's sounds right or have any advice for calculating the amount?
Old 09-09-2013, 05:44 AM
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Google Wallace Racing Calculators they have a great selection of automotive calculators and a good compression ratio one.
Old 09-09-2013, 07:13 AM
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Originally Posted by baronsmith98
Google Wallace Racing Calculators they have a great selection of automotive calculators and a good compression ratio one.
Many thanks for the reply I'll check it out
Old 09-09-2013, 07:16 AM
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http://www.wallaceracing.com/Calculators.htm

Originally Posted by TableLeg
Many thanks for the reply I'll check it out

For anybody else who comes across this post

Last edited by TableLeg; 09-09-2013 at 12:41 PM.
Old 09-09-2013, 07:02 PM
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I found the single quench pad LS1 heads 806/853/241 are .001 more for a cc then the 243/799 chamber. thats going to 56-54 cc. then you start cutting into the chamber more, but I would weld them up as your cutting .100 more so have to cut the intake face then.
I can't remember but think it was .006 per cc for them and its .007 per cc for the ls1 style. if you search I bet your find it. but I think you L33 has 243s
Old 09-10-2013, 08:19 AM
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Originally Posted by studderin
I found the single quench pad LS1 heads 806/853/241 are .001 more for a cc then the 243/799 chamber. thats going to 56-54 cc. then you start cutting into the chamber more, but I would weld them up as your cutting .100 more so have to cut the intake face then.
I can't remember but think it was .006 per cc for them and its .007 per cc for the ls1 style. if you search I bet your find it. but I think you L33 has 243s
Thanks for the reply.

My heads are definitely 799's, as are my pal's who also has an L33.



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