PRC Heads
Dec 31, 2007 | 12:49 PM
#11
Go with the 5.3 PRC heads and mill them .045, but you will probably need a shorter pushrod. If you are going to put heads might as well and raise your compression. I think PRC takes some meat off the combustions chamber. What is the chamber size?
Dec 31, 2007 | 12:51 PM
#12
these heads are DESIGNED for the 5.3. the specifics on these heads are to raise a 5.3's cr to 10.75:1. yes, the f-body guys use these heads aswell to raise compression, but they will raise it more than 10.75:1, being that it's already at 10:1, and the added smaller combustion chambers on these 5.3 heads would most likely raise it to over 11:1.
Dec 31, 2007 | 01:46 PM
#13
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you are incorrect in this statement.. a stock ls1's compression ratio is already 10:1.
these heads are DESIGNED for the 5.3. the specifics on these heads are to raise a 5.3's cr to 10.75:1. yes, the f-body guys use these heads aswell to raise compression, but they will raise it more than 10.75:1, being that it's already at 10:1, and the added smaller combustion chambers on these 5.3 heads would most likely raise it to over 11:1.
these heads are DESIGNED for the 5.3. the specifics on these heads are to raise a 5.3's cr to 10.75:1. yes, the f-body guys use these heads aswell to raise compression, but they will raise it more than 10.75:1, being that it's already at 10:1, and the added smaller combustion chambers on these 5.3 heads would most likely raise it to over 11:1.
Dec 31, 2007 | 03:17 PM
#15
you are incorrect in this statement.. a stock ls1's compression ratio is already 10:1.
these heads are DESIGNED for the 5.3. the specifics on these heads are to raise a 5.3's cr to 10.75:1. yes, the f-body guys use these heads aswell to raise compression, but they will raise it more than 10.75:1, being that it's already at 10:1, and the added smaller combustion chambers on these 5.3 heads would most likely raise it to over 11:1.
these heads are DESIGNED for the 5.3. the specifics on these heads are to raise a 5.3's cr to 10.75:1. yes, the f-body guys use these heads aswell to raise compression, but they will raise it more than 10.75:1, being that it's already at 10:1, and the added smaller combustion chambers on these 5.3 heads would most likely raise it to over 11:1.
Dec 31, 2007 | 03:20 PM
#17
The only way to know for sure is to find out what the combustion chamber size is. The reason is that If it is an original 61cc and they made it a 63cc or 64cc you're dropping your compression. Regardless if they were left at 61cc then your compression would not change. You would have to mill them a lot to get to 10.75:1 because your truck has 9.5:1. Unless you have flat top pistons.
i know the combustion chambers have been reduced considerably.
Dec 31, 2007 | 03:27 PM
#18
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I have done some research and calulations. If you find any of my numbers incorrect please let me know. This is with the stg 2.5 heads.
................................LM7 5.3........1998-2000 LS1......2001-2002 LS1
.................................................. .flat top piston
Bore..........................3.779............3.8 98..................3.898
Stroke.......................3.622............3.62 2..................3.622
Rod Length.................6.098............6.098..... .............6.098
Deck Height................-.006............-.006..................-.006
Piston Dish.................+2................0.......... ..............+2
Gasket Thickness........ 0.055............0.055..................0.055
Cumbustion Chamber... 63cc............63cc...................63cc
SCR..........................10.00:1.........10.76 :1................10.5:1
That is how I see them getting 10.75:1 SCR from an LSX with a flat top piston LS1.
BTW, this is just a friendly techincal discussion. Not trying to prove anyone wrong. This is just what I think TSP is getting their numbers from.
................................LM7 5.3........1998-2000 LS1......2001-2002 LS1
.................................................. .flat top piston
Bore..........................3.779............3.8 98..................3.898
Stroke.......................3.622............3.62 2..................3.622
Rod Length.................6.098............6.098..... .............6.098
Deck Height................-.006............-.006..................-.006
Piston Dish.................+2................0.......... ..............+2
Gasket Thickness........ 0.055............0.055..................0.055
Cumbustion Chamber... 63cc............63cc...................63cc
SCR..........................10.00:1.........10.76 :1................10.5:1
That is how I see them getting 10.75:1 SCR from an LSX with a flat top piston LS1.
BTW, this is just a friendly techincal discussion. Not trying to prove anyone wrong. This is just what I think TSP is getting their numbers from.
Dec 31, 2007 | 03:30 PM
#19
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The only way to know for sure is to find out what the combustion chamber size is. The reason is that If it is an original 61cc and they made it a 63cc or 64cc you're dropping your compression. Regardless if they were left at 61cc then your compression would not change. You would have to mill them a lot to get to 10.75:1 because your truck has 9.5:1. Unless you have flat top pistons.