ques on ls6 heads
Race Director
Joined: Feb 1999
Posts: 19,659
Likes: 34
From: Lenoir City Tennessee
Ci 6, 8 & 10 Veteran
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15
The heads will have the casting number 243 in them just at the front edge. Let me see if I have a pic that shows the number.
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
No you don't.
Although many parts are shared between the LS1 and LS6, the heads and cam are the two main ingredients that make the difference between 405hp and 350hp.
Your 2001 heads should have the 241 casting number,
LS6 heads are 243.
Although many parts are shared between the LS1 and LS6, the heads and cam are the two main ingredients that make the difference between 405hp and 350hp.
Your 2001 heads should have the 241 casting number,
LS6 heads are 243.
Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
20vette, the 241's flow pretty well compared to the older 853 (like what came on my 1997). The 243's have slightly higher compression than the 241's, but with careful head gasket and cam selection, you can probably get very similar performance out of your 241's that you would with the 243's. Ex, a friend had a Magic Stick 3, Ls6 intake, LG Street LT's, and stock 241's put down 430rwhp in his 2000 MN6 C5. I have a 228/232 (milder grind than the MS3), Texas Speed ported 243's, LS6 intake, and LG Street LT's and I put down 412rwhp/394tq. We were on different dynos, but the point is that he still put down great hp/tq #'s without investing $1000+ into heads.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
and there are or were two different 243 castings. Difference of 4-7 hp between the two different 243 castings.
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of the three casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads. View Related Article"
General Motors Gen III Engine Heads
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of the three casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads. View Related Article"
General Motors Gen III Engine Heads
Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
AU n EGL knows his stuff, listen up!
Of course if people are looking into aftermarket porting I would guess this casting difference would make less of a difference because its all getting hogged out anyway (as in my PRC 243's).
Of course if people are looking into aftermarket porting I would guess this casting difference would make less of a difference because its all getting hogged out anyway (as in my PRC 243's).
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Porting is a fine art. Some 243s have high flow numbers at .400, .500 and .600 lift, but poor air flow at .200 and .300 lift.
Some heads have great flow at .200, .300 and .400 and OK flow at .500 and .600 lift.
If you want SOTP, push yourself deep into your seat on take off, lots of under the curve torque, pick heads that have great flow at the .200 to.500 lift. If you want great HP numbers for bench, bar or forum racing, pic a high flow .500 and .600 lift and are big arz cam.
What it really comes down to IMO, figure out want you want your car to do? Drag race, weekend cruzer, DD, road race / track days or what ever.
Find and talk to a highly respected engine builder and tell them your needs. Have a budget, ( then double it) and let the engine builder do his magic.
Some heads have great flow at .200, .300 and .400 and OK flow at .500 and .600 lift.
If you want SOTP, push yourself deep into your seat on take off, lots of under the curve torque, pick heads that have great flow at the .200 to.500 lift. If you want great HP numbers for bench, bar or forum racing, pic a high flow .500 and .600 lift and are big arz cam.
What it really comes down to IMO, figure out want you want your car to do? Drag race, weekend cruzer, DD, road race / track days or what ever.
Find and talk to a highly respected engine builder and tell them your needs. Have a budget, ( then double it) and let the engine builder do his magic.
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Drifting
Joined: Dec 2005
Posts: 1,720
Likes: 3
From: East Hampton CT
I just logged onto the texas speed site (since I knew they posted flow rates) and it looks like their ported stg1 243 intake valves flow within +-5cfm of an AFR 205cc head between .200 and .500 lift. Of course exhaust might be another story (couldn't find that easily) but it goes to show you don't always have to spend $$$$$$ to get decent performance. That said, I'm not going to start a war here by saying that X head is as good as an AFR....there have been plenty of members that have proven that AFR makes an excellent head for almost any setup. Lastly, you need to read between the numbers....many people claim much better drivability with the AFR's regardless of the #'s that they claim.
I've been happy with my PRC 243's and the extra $$$ I saved was put toward other mods that I felt were more worthwhile for what I'm trying to accomplish.
I've been happy with my PRC 243's and the extra $$$ I saved was put toward other mods that I felt were more worthwhile for what I'm trying to accomplish.
Team Owner
Joined: Sep 2003
Posts: 43,084
Likes: 33
From: Raleigh / Rolesville NC
Burning Brakes
Joined: Jul 2000
Posts: 1,134
Likes: 1
From: Arlington Texas
and there are or were two different 243 castings. Difference of 4-7 hp between the two different 243 castings.
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of the three casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads. View Related Article"
General Motors Gen III Engine Heads
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of the three casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads. View Related Article"
General Motors Gen III Engine Heads
Melting Slicks
Joined: Jun 2007
Posts: 2,172
Likes: 1
From: Sartell Minnesota
That's GREAT info to know about the 243 heads because that's the style i have
i bought them off a guy from another forum for $275. i didn't think it was too bad. Only thing wrong with them was a header bolt hole was slightly stripped so i Helicoiled it and that's fixed now. COOL COOL. man i JUST noticed those triangles today and now i read this
Made my day~Cole~
i bought them off a guy from another forum for $275. i didn't think it was too bad. Only thing wrong with them was a header bolt hole was slightly stripped so i Helicoiled it and that's fixed now. COOL COOL. man i JUST noticed those triangles today and now i read this Made my day~Cole~
MFIC
Joined: Aug 2005
Posts: 1,997
Likes: 14
From: Charlotte, North Carolina
Lucky me ! thats the ones I got for my car, I'm cleaning them up right now.
and there are or were two different 243 castings. Difference of 4-7 hp between the two different 243 castings.
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of the three casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads. View Related Article"
General Motors Gen III Engine Heads
"Here's a secret: If you want the best heads for performance, make sure your heads have these small triangle marks below every spark plug hole. The marks are left by "chills" used during the casting process in GM's semi-permanent mold (SPM) tooling. Of the three casting facilities that make Gen III cylinder heads, two use SPM tooling, the other heads are sand-cast. The SPM tools produce heads with very smooth, consistent ports and chambers which consistently dyno at least 4 to 7 hp better than the sand-cast heads. View Related Article"
General Motors Gen III Engine Heads
Safety Car
Joined: Aug 2007
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