Best Heads for C6
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Instructor
Joined: Feb 2006
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Best Heads for C6
I want more power from my c6 but i wanna keep it naturally aspirated.
I already have Longtubes, predator, and air intake and was wondering which heads make the most power and where can i order them? I dont wanna change the cam cause i like the way the car drives now and i hear by changing the cam it wont be as reliable. correct me if im wrong. Thanks
I already have Longtubes, predator, and air intake and was wondering which heads make the most power and where can i order them? I dont wanna change the cam cause i like the way the car drives now and i hear by changing the cam it wont be as reliable. correct me if im wrong. Thanks
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
I want more power from my c6 but i wanna keep it naturally aspirated.
I already have Longtubes, predator, and air intake and was wondering which heads make the most power and where can i order them? I dont wanna change the cam cause i like the way the car drives now and i hear by changing the cam it wont be as reliable. correct me if im wrong. Thanks
I already have Longtubes, predator, and air intake and was wondering which heads make the most power and where can i order them? I dont wanna change the cam cause i like the way the car drives now and i hear by changing the cam it wont be as reliable. correct me if im wrong. Thanks
Race Director
Joined: Oct 2004
Posts: 10,516
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From: Virginia Bch VA
Cruise-In VI Veteran
Cruise-In VII Veteran
St. Jude Donor '06
Spin is right on but his price quote may be a little off.
CARTEK preaches that the stock heads Ported are the best. I went in there planning to spend big bucks on AFRs, TrickFlow, or RHS/ET heads. They talked me out of that. The RHS/ETs with 4 degrees less valve angle are attrictive. Cam choice is another story.
I strongly recommend that you go with a proven package rather than a mix & match approach.
CARTEK preaches that the stock heads Ported are the best. I went in there planning to spend big bucks on AFRs, TrickFlow, or RHS/ET heads. They talked me out of that. The RHS/ETs with 4 degrees less valve angle are attrictive. Cam choice is another story.
I strongly recommend that you go with a proven package rather than a mix & match approach.
Racer
Joined: Dec 2006
Posts: 322
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From: Alexandria Louisiana
St. Jude Donor '08
N/A vs Boosted
Spin is right on but his price quote may be a little off.
CARTEK preaches that the stock heads Ported are the best. I went in there planning to spend big bucks on AFRs, TrickFlow, or RHS/ET heads. They talked me out of that. The RHS/ETs with 4 degrees less valve angle are attrictive. Cam choice is another story.
I strongly recommend that you go with a proven package rather than a mix & match approach.
CARTEK preaches that the stock heads Ported are the best. I went in there planning to spend big bucks on AFRs, TrickFlow, or RHS/ET heads. They talked me out of that. The RHS/ETs with 4 degrees less valve angle are attrictive. Cam choice is another story.
I strongly recommend that you go with a proven package rather than a mix & match approach.
I have some ported Stage 2 heads on my F1-R'ed 383 & every time I talk about kicking the boost up from its' present 14# my tuner ( who didn't build the car ) tells me that the heads' thin decks R gonna allow headlift. 
I'm considering moving up to AFR's ( any advice for a street driven car - 205's or 225's? ) but not if I really don't need them. 
I'd like to step up to 17# ( about all the Michelins can MAYBE handle 
) but not at the expense of problems. Thanks & everyone can chip in here!! 
Gene
Melting Slicks
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From: Acton MA
Race Director
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From: Virginia Bch VA
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St. Jude Donor '06
JF - Does the Cartek rule of thumb also apply to boosted cars, IYHO? I have some ported Stage 2 heads on my F1-R'ed 383 & every time I talk about kicking the boost up from its' present 14# my tuner ( who didn't build the car ) tells me that the heads' thin decks R gonna allow headlift. I'm considering moving up to AFR's ( any advice for a street driven car - 205's or 225's? ) but not if I really don't need them. I'd like to step up to 17# ( about all the Michelins can MAYBE handle ) but not at the expense of problems. Thanks & everyone can chip in here!!
Gene
I have some ported Stage 2 heads on my F1-R'ed 383 & every time I talk about kicking the boost up from its' present 14# my tuner ( who didn't build the car ) tells me that the heads' thin decks R gonna allow headlift. I'm considering moving up to AFR's ( any advice for a street driven car - 205's or 225's? ) but not if I really don't need them. I'd like to step up to 17# ( about all the Michelins can MAYBE handle ) but not at the expense of problems. Thanks & everyone can chip in here!! Gene
I am really NOT the guy to answer this with any acceptable level of authority. But here’s what I know:
NA motors do best when keeping the flow rates high on both the intake & exhaust side. i.e. you do best with 205-210 fuel runners, 1¾” exhaust headers and a relatively moderate CAM (224-232 range w/113-114 LSA). Once you go to FI you need 220-230 fuel intake runners and 1 7/8 headers with higher cam duration. Once there you also need to check your fuel flow to determine if upgraded injectors are required. My understanding is that a fuel booster pump is another requirement.
There are a few here that could give you a better answer. ShopDog; SpinMonster; AndreasG, and TommyD come to mind quickly. Personally I would direct that question to a reputable tunner shop like CATREK, East Coast, England Green or Vette DRs.
JT
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Racer
Joined: Dec 2006
Posts: 322
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From: Alexandria Louisiana
St. Jude Donor '08
Gene,
I am really NOT the guy to answer this with any acceptable level of authority. But here’s what I know:
NA motors do best when keeping the flow rates high on both the intake & exhaust side. i.e. you do best with 205-210 fuel runners, 1¾” exhaust headers and a relatively moderate CAM (224-232 range w/113-114 LSA). Once you go to FI you need 220-230 fuel intake runners and 1 7/8 headers with higher cam duration. Once there you also need to check your fuel flow to determine if upgraded injectors are required. My understanding is that a fuel booster pump is another requirement.
There are a few here that could give you a better answer. ShopDog; SpinMonster; AndreasG, and TommyD come to mind quickly. Personally I would direct that question to a reputable tunner shop like CATREK, East Coast, England Green or Vette DRs.
JT
I am really NOT the guy to answer this with any acceptable level of authority. But here’s what I know:
NA motors do best when keeping the flow rates high on both the intake & exhaust side. i.e. you do best with 205-210 fuel runners, 1¾” exhaust headers and a relatively moderate CAM (224-232 range w/113-114 LSA). Once you go to FI you need 220-230 fuel intake runners and 1 7/8 headers with higher cam duration. Once there you also need to check your fuel flow to determine if upgraded injectors are required. My understanding is that a fuel booster pump is another requirement.
There are a few here that could give you a better answer. ShopDog; SpinMonster; AndreasG, and TommyD come to mind quickly. Personally I would direct that question to a reputable tunner shop like CATREK, East Coast, England Green or Vette DRs.
JT
JT - Thanks for the advice! I have an email into Tony @ AFR should I choose to swap heads & I'll send on to some of the vendors U mentioned as well. I have Kooks 1 7/8" headers & 60# injectors w/a KB Boost-a-pump but my cam profile isn't that radical ( 224/227 & .563/569 ). Guess we'll see what some of the shops say & thanks again!!
Gene
Tech Contributor
Joined: Mar 2003
Posts: 12,094
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
Power has been gotten from many heads. The more imortant issue is the tuner that is doing the install and getting a match with the heads you pick. I dont know anything about the tuners in your area but you should go with a tuner that has produced fast cars not big dyno numbers.
I've seen heads, cam, S/C go 11.2 and I have seen a cam only car go 11.2. You do the math.
AFR's have the best low rpm throttle response. They are the total inverse of L92's. 205cc runners vs. 260cc runners. Anyone on the list of 10 second cars running them?
I've seen heads, cam, S/C go 11.2 and I have seen a cam only car go 11.2. You do the math.
AFR's have the best low rpm throttle response. They are the total inverse of L92's. 205cc runners vs. 260cc runners. Anyone on the list of 10 second cars running them?
Racer
Joined: Dec 2006
Posts: 322
Likes: 0
From: Alexandria Louisiana
St. Jude Donor '08
Dyno vs Times
Power has been gotten from many heads. The more imortant issue is the tuner that is doing the install and getting a match with the heads you pick. I dont know anything about the tuners in your area but you should go with a tuner that has produced fast cars not big dyno numbers.
I've seen heads, cam, S/C go 11.2 and I have seen a cam only car go 11.2. You do the math.
AFR's have the best low rpm throttle response. They are the total inverse of L92's. 205cc runners vs. 260cc runners. Anyone on the list of 10 second cars running them?
I've seen heads, cam, S/C go 11.2 and I have seen a cam only car go 11.2. You do the math.
AFR's have the best low rpm throttle response. They are the total inverse of L92's. 205cc runners vs. 260cc runners. Anyone on the list of 10 second cars running them?
Sounds like you feel like the AFR's would be best for a mostly street driven car so would u choose their 205's or the 225's? My history w/heads revolves around Brodix & they don't make heads for the LS1. Thanks for jumping in with your knowledge & keep it coming!!
Gene
Safety Car
Joined: Dec 2004
Posts: 4,477
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From: Boca Raton, FL
St. Jude Donor '05-'06-'07-'08-'09-'10-'11-'12-'13-'14
Power has been gotten from many heads. The more imortant issue is the tuner that is doing the install and getting a match with the heads you pick. I dont know anything about the tuners in your area but you should go with a tuner that has produced fast cars not big dyno numbers.
I've seen heads, cam, S/C go 11.2 and I have seen a cam only car go 11.2. You do the math.
AFR's have the best low rpm throttle response. They are the total inverse of L92's. 205cc runners vs. 260cc runners. Anyone on the list of 10 second cars running them?
I've seen heads, cam, S/C go 11.2 and I have seen a cam only car go 11.2. You do the math.
AFR's have the best low rpm throttle response. They are the total inverse of L92's. 205cc runners vs. 260cc runners. Anyone on the list of 10 second cars running them?
Team Owner
Joined: Oct 2001
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Guest
Posts: n/a
Like everything else, it is a matter on how much you want to spend.
Tried and true are the AFR's, however Trick Flow seem to be the heads of choice for the cathedral port design these days along with a ported FAST intake. Pleanty of proven cams with this set up depending on how "streetable" you want it, however many view the cathedral ports heads as yesterday'stechnology.
LS7 ports are the future, i.e., CNC ported L92's from Livernois or WCCH with a L76 intake seem to be top choices - both have produced >500whp, or ET Performance LS74.0, which are designed for the 6L engine and use the LS7 intake. The designs are evolving on a daily basis, however, they already flowing better, make more power and cost less than a AFR/FAST cathedral setup.
You could probably squeeze another 40hp from a sheetmetal intake, but plan on dropping $3K or so for one. You money would be better spent on a 402 stroker kit.
Tried and true are the AFR's, however Trick Flow seem to be the heads of choice for the cathedral port design these days along with a ported FAST intake. Pleanty of proven cams with this set up depending on how "streetable" you want it, however many view the cathedral ports heads as yesterday'stechnology.
LS7 ports are the future, i.e., CNC ported L92's from Livernois or WCCH with a L76 intake seem to be top choices - both have produced >500whp, or ET Performance LS74.0, which are designed for the 6L engine and use the LS7 intake. The designs are evolving on a daily basis, however, they already flowing better, make more power and cost less than a AFR/FAST cathedral setup.
You could probably squeeze another 40hp from a sheetmetal intake, but plan on dropping $3K or so for one. You money would be better spent on a 402 stroker kit.
Last edited by aTX427; Jun 26, 2007 at 07:41 PM.
SC CF Senior Member
Joined: Feb 2006
Posts: 1,227
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From: Friendswood Texas
St. Jude Donor '06-'07-'08
Very good article! Trick Flow seems to be a pretty solid choice. However, can't go wrong with AFR's name!
http://www.gmhightechperformance.com...ylinder_heads/
John
http://www.gmhightechperformance.com...ylinder_heads/
John
Burning Brakes
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From: LAS VEGAS NV
Race Director
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From: Virginia Bch VA
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St. Jude Donor '06
However I would investigate the RHS/ET Heads. I am told that ET makes them for RHS (a COMPCAM Family Corp). What is attractive is that the valve angle in the head is 11 deg vice 15 deg in the stock head. Two advantages here:
1. Better flow
2. Tolerates greater valve lift without piston interference
Racer
Joined: Dec 2006
Posts: 322
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From: Alexandria Louisiana
St. Jude Donor '08
Deck Thickness
However I would investigate the RHS/ET Heads. I am told that ET makes them for RHS (a COMPCAM Family Corp). What is attractive is that the valve angle in the head is 11 deg vice 15 deg in the stock head. Two advantages here:
1. Better flow
2. Tolerates greater valve lift without piston interference
because there's good info in here but where does the deck thickness become important ( other than allowing for milling & thus affecting the CR )? AFR states in their ads that they have 3/4" thick decks which "lend themselves well for blown & nitrous applications". Since my concern is more about head lift due to increased boost
& after looking at the GM head link it seems like ALL the heads tested are exceptional 
, price starts to become the limiting factor. 
I've asked my tuner about just swapping the head studs to the ARP L-19's but he said that, IHO, the heads R the issue, not so much the clamping force. Haven't heard from Paul @ AFR yet, BTW.Gene
Last edited by Mean Gene55; Jun 27, 2007 at 11:14 AM. Reason: Correction
Safety Car
Joined: Jun 2004
Posts: 3,563
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From: Dallas Tx
You like the way it runs, don't want to change the cam, want reliability... leave it alone.
The stock heads flow plenty for the stock cam. Break open the engine for a head swap and reliability becomes an unknown. It's the u touched it theory.
Compare hood openings with a stock vet versus a modified. I've got a stock vette. I open my hood once in a blue moon, maybe a couple times a year to change the oil. I've got a neighbor with a modified vette, heads cam headers ... I swear everday I hear his hood shutting after he is tinkering with something. Every weekend he's got some major project going either fixing something or trying something else that didn't quite work. I drive mine and wash it. His has spent more time on jackstands than mine has been on the road.
The stock heads flow plenty for the stock cam. Break open the engine for a head swap and reliability becomes an unknown. It's the u touched it theory.
Compare hood openings with a stock vet versus a modified. I've got a stock vette. I open my hood once in a blue moon, maybe a couple times a year to change the oil. I've got a neighbor with a modified vette, heads cam headers ... I swear everday I hear his hood shutting after he is tinkering with something. Every weekend he's got some major project going either fixing something or trying something else that didn't quite work. I drive mine and wash it. His has spent more time on jackstands than mine has been on the road.