6.0L Heads - How much will these lower CR?
05-08-2006, 06:55 PM
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6.0L Heads - How much will these lower CR? Ive got a set of 6.0L GM heads that Im gettin ported here in the next week or so. They have 71.6 (est) cc Chambers. How much do these lower the CR? TIA
05-09-2006, 12:08 AM
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You want the LQ9 heads with the 317 CASTING #s which are the 72cc heads (the 317s casting #s being the 72cc boost friendly heads I am postive about)! 
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05-09-2006, 12:17 AM
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i am looking into the "317" LQ9 heads for my setup.. but there are two casting numbers i ahve here in my LS1/LS6 Will Handzel book..with only one number difference in them.. the exact numbers are #12572317 and #12562317 -the first number you see are suppoedly the "LQ9" castings, then the second # are the castings for the "LQ4" heads...anyone wanna back my info up here..jus wanna be 100% positive before i go double check the shitload of heads i saw yesterday with the 317# at the end of each casting # 
05-09-2006, 12:24 AM
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well stock ls1's should be approximately 10.1 not sure of the 10.5's ppl think but ya. as for the 317 heads they should drop it about 1 full point making it close to 9.1 so pretty boost happy range 
good luck
good luck
05-09-2006, 10:55 PM
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Does anyone have any idea of how much boost will decrese from where Im at now...I plan on running a smaller pulley to get my boost back around the 9psi area. I was wondering so I can try to figure out what pulley size Ill need to go with to regain my boost that is lost.
Im running a 4.0 with the MMS Overdrive Crank!
Im running a 4.0 with the MMS Overdrive Crank!
05-09-2006, 11:36 PM
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well i just installed my friend vortech v9 g-trim aftercooled setup(8-9psi) with FAST 78mm Manifold/TB, SLP LT's/Borla...and we're only seeing 5-6psi at most due to the improved flow of the headers/manifold/throttle body etc..technically it SUCKS but the power is definitely there.....anyways im assuming heads will drop ur boost levels even more so i'd shoot for the pulley size that was meant for 12psi or so on a "stock" motor...that should even things out a bit....
ALSO remember that you gotta accomodate everything else for the jump in power and boost...which im sure u probably already know by the looks of the mods in ur sig. Anyways yea im referring to fuel system/air fuel/ and a badass new TUNE or else something might
ALSO remember that you gotta accomodate everything else for the jump in power and boost...which im sure u probably already know by the looks of the mods in ur sig. Anyways yea im referring to fuel system/air fuel/ and a badass new TUNE or else something might
05-11-2006, 12:09 AM
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Yea thats what I was thinking a 12# pulley should be pretty close!
I figure with the MMS a 3.8 or 3.7 should be pretty close...I figure one of those would have made 12 psi before the heads...
I figure with the MMS a 3.8 or 3.7 should be pretty close...I figure one of those would have made 12 psi before the heads...
