Calling all LS2 Experts
Tech Contributor
Joined: Jul 2002
Posts: 14,949
Likes: 263
From: St. Louis, MO
St. Jude Donor '08
Gee, what does CNC ported Mean???
From http://www.gmperformanceparts.com/Pa...input=12564825
For those that have the 799 head and the rumor of GM dumping out these old Ls6 head, you may just be the lucky ones. The old ls6
Cylinder Head - Cnc Mach Showroom Stock Version Of 2002 LS6 Head
CNC-ported aluminum racing head
2.00" Hollow stem intake, and 1.55" sodium filled exhaust valves
.570" max valve lift
250 cc CNC'd "Cathedral port" intake ports
85 cc CNC'd D-shaped exhaust ports
61.9 cc CNC'd combustion chambers
Bare head p/n 12564825
The super good hollow valves.... small combustion chamber.
WOW
From http://www.gmperformanceparts.com/Pa...input=12564825
For those that have the 799 head and the rumor of GM dumping out these old Ls6 head, you may just be the lucky ones. The old ls6
Cylinder Head - Cnc Mach Showroom Stock Version Of 2002 LS6 Head
CNC-ported aluminum racing head
2.00" Hollow stem intake, and 1.55" sodium filled exhaust valves
.570" max valve lift
250 cc CNC'd "Cathedral port" intake ports
85 cc CNC'd D-shaped exhaust ports
61.9 cc CNC'd combustion chambers
Bare head p/n 12564825
The super good hollow valves.... small combustion chamber.
WOW
My buddy has the GMperformance CnC heads on his car. I have a call into him to check on his car and I'll report back what #'s he has.
Tech Contributor
Joined: Jul 2002
Posts: 14,949
Likes: 263
From: St. Louis, MO
St. Jude Donor '08
He called back. He's got 243's. These were purchased from GM Performance a couple of years ago when GM CnC Ls6 heads were pretty hot, before AFR's were so popular.
Racer
Joined: May 2004
Posts: 370
Likes: 0
From: Orlando FL
The 799 on the passenger side is stamped at the firewall end, and the 243 on the driver's side is stamped on the firewall end as well, with nothing stamped in the same location on the forward end of either.
Jim
Team Owner
Joined: Oct 2001
Posts: 56,377
Likes: 79
http://forums.corvetteforum.com/show...post1559680674
243 vs. 799 heads talked to GM research tonight.
I talked to Bob (Gohard777) and Mr. X. There is no difference between the two heads. The numbers tell what original mold the casting came from. 243 mold was done at GM Research, the 799 mold is used by other vendors. The same vendor will have 243 and 799 molds. The numbers are just a GM system for when the mold was made. If a head had a problem it helps them track down where the problem started. The only difference between the heads is production variance. Case closed. Thanks to Bob and Mr. X. Mr. X machined the first 243 heads himself at GM Research.
243 vs. 799 heads talked to GM research tonight.
I talked to Bob (Gohard777) and Mr. X. There is no difference between the two heads. The numbers tell what original mold the casting came from. 243 mold was done at GM Research, the 799 mold is used by other vendors. The same vendor will have 243 and 799 molds. The numbers are just a GM system for when the mold was made. If a head had a problem it helps them track down where the problem started. The only difference between the heads is production variance. Case closed. Thanks to Bob and Mr. X. Mr. X machined the first 243 heads himself at GM Research.
Melting Slicks
Joined: Oct 2005
Posts: 3,053
Likes: 0
From: NorCal
http://forums.corvetteforum.com/show...post1559680674
243 vs. 799 heads talked to GM research tonight.
I talked to Bob (Gohard777) and Mr. X. There is no difference between the two heads. The numbers tell what original mold the casting came from. 243 mold was done at GM Research, the 799 mold is used by other vendors. The same vendor will have 243 and 799 molds. The numbers are just a GM system for when the mold was made. If a head had a problem it helps them track down where the problem started. The only difference between the heads is production variance. Case closed. Thanks to Bob and Mr. X. Mr. X machined the first 243 heads himself at GM Research.
243 vs. 799 heads talked to GM research tonight.
I talked to Bob (Gohard777) and Mr. X. There is no difference between the two heads. The numbers tell what original mold the casting came from. 243 mold was done at GM Research, the 799 mold is used by other vendors. The same vendor will have 243 and 799 molds. The numbers are just a GM system for when the mold was made. If a head had a problem it helps them track down where the problem started. The only difference between the heads is production variance. Case closed. Thanks to Bob and Mr. X. Mr. X machined the first 243 heads himself at GM Research.
Now that is solved we can focus on the problem of low dyno numbers. First, that is pretty good numbers for the mods you have done, would be nice to be a little better. I would look at the problem in this order.1. Your tuner and the software he used, not all are alike (or good) I race a LS1 and only HPTuners software is used.
2. Fuel - Injectors and fuel pump could be a small marble in the funnel.
3. Go back and check everything on the air in take system you installed. And understand on a dyno the intake system is not going to do you much good as there is no ram air effect. (forced air)
Good luck.
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Heel & Toe
Joined: Apr 2007
Posts: 18
Likes: 0
From: Springfield Missouri
After reading this I checked my SS Silverado when I was washing it earlier and the passenger side iss 317 and drivers side started with a 2. I have a bad back and could not reach to move the hose out of the way blocking my view.
Drifting
Joined: May 2001
Posts: 1,936
Likes: 0
From: Clemmons NC
Gee, what does CNC ported Mean???
From http://www.gmperformanceparts.com/Pa...input=12564825
For those that have the 799 head and the rumor of GM dumping out these old Ls6 head, you may just be the lucky ones. The old ls6
Cylinder Head - Cnc Mach Showroom Stock Version Of 2002 LS6 Head
CNC-ported aluminum racing head
2.00" Hollow stem intake, and 1.55" sodium filled exhaust valves
.570" max valve lift
250 cc CNC'd "Cathedral port" intake ports
85 cc CNC'd D-shaped exhaust ports
61.9 cc CNC'd combustion chambers
Bare head p/n 12564825
The super good hollow valves.... small combustion chamber.
WOW
From http://www.gmperformanceparts.com/Pa...input=12564825
For those that have the 799 head and the rumor of GM dumping out these old Ls6 head, you may just be the lucky ones. The old ls6
Cylinder Head - Cnc Mach Showroom Stock Version Of 2002 LS6 Head
CNC-ported aluminum racing head
2.00" Hollow stem intake, and 1.55" sodium filled exhaust valves
.570" max valve lift
250 cc CNC'd "Cathedral port" intake ports
85 cc CNC'd D-shaped exhaust ports
61.9 cc CNC'd combustion chambers
Bare head p/n 12564825
The super good hollow valves.... small combustion chamber.
WOW
Safety Car
Joined: Feb 2007
Posts: 4,684
Likes: 107
From: Opelika Alabama
hp
2006 mn6 243 heads just pulled 364rwhp with just a predator 93 octane tune with 91 octane fuel, just put new 91 tune in the other day it feels like that gave it even more, car is bone stock!!
Instructor
Joined: Apr 2009
Posts: 194
Likes: 0
From: Portland OR
St. Jude Donor '10
Instructor
Joined: Apr 2009
Posts: 194
Likes: 0
From: Portland OR
St. Jude Donor '10
