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11.0:1 compression on standard heads? is it possible?

   
Old 09-06-2012, 08:49 AM
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Default 11.0:1 compression on standard heads? is it possible?
was just wondering if it is possible for me to deck a set of standard ls1 heads to get my compression to 11:1

cheers
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Old 09-06-2012, 08:54 AM
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Very possible. Up to around 12.75:1
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Old 09-06-2012, 08:55 AM
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Depending on head gasket thickness and how much you mill
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Old 09-06-2012, 09:16 AM
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Very possible. Up to around 12.75:1
How much do you have to mill 241 heads to get an ls1 to 12.8 comp ratio?
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Old 09-06-2012, 09:35 AM
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Originally Posted by Glenno108
was just wondering if it is possible for me to deck a set of standard ls1 heads to get my compression to 11:1

cheers
What short-block are we working with, and which casting number heads are you about to mill?
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Old 09-06-2012, 09:49 AM
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I have my 241's milled down to 57cc chambers to give me 12.5:1 on my 408... On a 346ci I think that would put you around 11.75:1
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Old 09-06-2012, 10:10 AM
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i was wanting to know my compression i have a stock ls1 with 241s milled .030 and a stock head gasket can someone tell me what it is know and what i can do to get 11.5?
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Old 09-06-2012, 10:34 AM
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I have stock bottom end with 243 heads milled to over 13:1, with 4cc valve releifs
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Old 09-06-2012, 10:39 AM
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Originally Posted by 95_lt1formula
i was wanting to know my compression i have a stock ls1 with 241s milled .030 and a stock head gasket can someone tell me what it is know and what i can do to get 11.5?
Those heads milled .030" should give you about 61cc cambers. With GM head gaskets that should be about 11.1 CR. If you used Cometic .041" gaskets, that would put you around 11.4 CR.
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Old 09-06-2012, 10:43 AM
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Originally Posted by Grr
I have stock bottom end with 243 heads milled to over 13:1, with 4cc valve releifs
No way, even with .041" gaskets, you'd need to cut the heads down to 48cc chambers which would be nearly .100" milled on 243 heads. That's not gonna happen.
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Old 09-06-2012, 11:03 AM
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I definitely think its possible but you will want to make sure you have enough clearance with your cam, or just go ahead and flycut if you have a big cam.
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Old 09-06-2012, 12:13 PM
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Very possible. Up to around 12.75:1
I have stock bottom end with 243 heads milled to over 13:1, with 4cc valve releifs
I think some of you have no clue how to use a static compression calculator if that's what you think your stock bottom end engines are running with just a bunch of milled 241/243 heads.
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Old 09-06-2012, 02:29 PM
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Originally Posted by batboy
No way, even with .041" gaskets, you'd need to cut the heads down to 48cc chambers which would be nearly .100" milled on 243 heads. That's not gonna happen.
Originally Posted by redtan
I think some of you have no clue how to use a static compression calculator if that's what you think your stock bottom end engines are running with just a bunch of milled 241/243 heads.

My heads are milled over .100, they are 46cc

Figure it out before you look even less intelligent

My DCR is 9.75:1, I use E85
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Old 09-06-2012, 04:10 PM
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Originally Posted by redtan
How much do you have to mill 241 heads to get an ls1 to 12.8 comp ratio?
between .080 and .110, would need .040 gasket and around 53cc.
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Old 09-06-2012, 06:27 PM
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If you milled the heads that much, the intake would not fit right and the bolt holes would not line up. I highly doubt you could use the listed cam and not have piston to valve clearance problems.
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Old 09-06-2012, 06:44 PM
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well its all in there, like it or not. pistons are flycut .140,
and if the intake wouldnt fit right wouldnt you think I would just have milled it as well so it fits?
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Old 09-08-2012, 07:56 PM
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Originally Posted by Matt@Texas-Speed
What short-block are we working with, and which casting number heads are you about to mill?
241 heads i have some .040 gaskets and stock bottom end, just trying to do as much research before i attack it on the mill.
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Old 09-09-2012, 03:57 AM
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Also milling 30thou off and having .612 lift shouldn't have piston and valve troubles would I?
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Old 09-09-2012, 06:33 AM
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Originally Posted by Glenno108
Also milling 30thou off and having .612 lift shouldn't have piston and valve troubles would I?
peak lift doesn't affect PTV much, if at all. PTV issues happen within +/- 15-deg of TDC.
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Old 09-09-2012, 08:28 AM
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Originally Posted by redtan
I think some of you have no clue how to use a static compression calculator if that's what you think your stock bottom end engines are running with just a bunch of milled 241/243 heads.
ha, it's totally possible to shave .100 off the heads.... angle milling ftw.
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