GMP LS6 CNC Heads
Thread Starter
Instructor
Joined: Oct 1999
Posts: 179
Likes: 2
From: Somerville NJ
GMP LS6 CNC Heads
Anyone using the GM Performance LS6 cnc-ported heads? Wondering if they give much if any gains over the stock LS6 heads. Did a couple searches and didn't find any references to them. 
Burning Brakes
Joined: Jan 2002
Posts: 885
Likes: 0
From: The Woodlands Texas
I don't hink the heads will offer much in the way of actual performance gains by themselves. They can be ported to allow larger volumes of fuel / gas mix and waste exhaust to flow in / out but you will need a cam to bring the package together.
One advantage with the GM heads is that you would not void your GM warranty if you went with the factory Z06 heads / cam setup. Should be able to bolt-on around 60-70 RWHP and still stay warranty legal.
One advantage with the GM heads is that you would not void your GM warranty if you went with the factory Z06 heads / cam setup. Should be able to bolt-on around 60-70 RWHP and still stay warranty legal.
Drifting
Joined: Aug 2000
Posts: 1,253
Likes: 3
From: Chapel Hill NC
The GMPP heads are stock 02+ LS6 ported by LPE and were developed for competition use, like the World Challenge Vette Lou Gigliotti drives, and with a cam like the GMPP Grand-Am Cup cam the WC Vettes run. If you don't have a bigger cam you won't come close to realizing the head's potential, though you'd get some hp improvement. With the right cam, I'd guess they might be worth 40hp or so. Maybe more if you get the high comp. version. For better info, call LPE and talk to Ed Potter, Scoggins-Dickey, or try LS1tech.com.
Safety Car
Joined: Nov 2003
Posts: 4,979
Likes: 5
From: San Diego, CA "leaf" "tee" "e"
Originally Posted by tcmc5
The GMPP heads are stock 02+ LS6 ported by LPE and were developed for competition use, like the World Challenge Vette Lou Gigliotti drives, and with a cam like the GMPP Grand-Am Cup cam the WC Vettes run. If you don't have a bigger cam you won't come close to realizing the head's potential, though you'd get some hp improvement. With the right cam, I'd guess they might be worth 40hp or so. Maybe more if you get the high comp. version. For better info, call LPE and talk to Ed Potter, Scoggins-Dickey, or try LS1tech.com.
These are also the same heads that LG has been having problems with on his race car.
Drifting
Joined: Aug 2000
Posts: 1,253
Likes: 3
From: Chapel Hill NC
Originally Posted by leaftye
These are also the same heads that LG has been having problems with on his race car.
Drifting
Joined: Aug 2000
Posts: 1,253
Likes: 3
From: Chapel Hill NC
The heads were cracking from the stress of operating at up to 7500 rpm for 45min or so 
The extensive porting probably weakens them structurally. I'd guess they're quite reliable in less stressful use.
The extensive porting probably weakens them structurally. I'd guess they're quite reliable in less stressful use.
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Drifting
Joined: Feb 2002
Posts: 1,630
Likes: 125
From: Park Ridge Illinois
2022 C5 of the Year Finalist - Modified
2021 C5 of the Year Finalist - Modified
I ran these heads with great results. They flow over 306cfm at .550 lift with stock valves. On my automatic car I acheived 400rwh with these heads and the LPE GT2-3 cam, which is a very mild cam. With these heads and a 224 cam, 430+ is no problem on a manual car. I have these heads currently for sale only because I went forced induction. PM for details or pics. 
Drifting
Joined: May 2002
Posts: 1,607
Likes: 1
From: San Francisco CA
The problem with these heads, as I understand it, is that because of core shift during manufacture, the thickness of the port walls can vary. The when the heads are CNC ported, the area under the rocker arm stud can end up very thin sometimes. It is almost always not a problem with the supplied springs but can be if stronger springs are used.
The peak flow #s are great but they come at the expense of lower port velocity because of very large cc ports, which can mean a loss of low speed torque compared to other heads
The peak flow #s are great but they come at the expense of lower port velocity because of very large cc ports, which can mean a loss of low speed torque compared to other heads
