Head info?
Thread Starter
Drifting
Joined: May 2005
Posts: 1,590
Likes: 1
From: Littleton Colorado
Head info?
Ok, I’m looking at the different cylinder heads around and its getting confusing. So, if anyone could clue me in on some of the differences and answer some of my questions that would be great. Or if you could refer me to a good web write up that would be great as well. I’m looking to upgrade a LS1, and I don’t really see going FI with it or anything more than a stroker kit. My goal is a set of heads that will help me get a lot of torque.
What are the differences between the ‘Stage’s that are advertised for some heads, like ‘stage 2.5’. I assume that there are no hard rules, but that there would be some loose standards as to what each stage would encompass.
I know the AFR 205’s are great, lots of people have good luck with them and no real complaints about them. However, I’d like to find out some more info as I may not want to go with the AFRs, but than again I may.
What about valve size? Are there significant differences in different heads, or will they be in the same neighborhood?
How do the CNC’ed LS6 heads compare to the LS6 heads or the AFR 205’s?
What are the differences between the ‘Stage’s that are advertised for some heads, like ‘stage 2.5’. I assume that there are no hard rules, but that there would be some loose standards as to what each stage would encompass.
I know the AFR 205’s are great, lots of people have good luck with them and no real complaints about them. However, I’d like to find out some more info as I may not want to go with the AFRs, but than again I may.
What about valve size? Are there significant differences in different heads, or will they be in the same neighborhood?
How do the CNC’ed LS6 heads compare to the LS6 heads or the AFR 205’s?
Former Vendor
Joined: Mar 2006
Posts: 153
Likes: 0
Stages are primarily marketing tools. Unfortunately, there are no rules other than a Stage 3 or III (depending on whether or not said vendor uses Roman numerals) should be ‘better’ than a Stage 2 (II) which should be ‘better’ than a Stage 1 (I) which should be better than stock. Well, what does that mean? It is truly hard to say. In general (and often unfortunately), heads are measured by their peak flow as most people assume more flow = more power. But, as it has been proven time and time again the whole setup or combination is much more important than just peak flow. Unfortunately, one tuner’s Stage 2 may include larger valves when another tuner’s does not. So, it is impractical to compare various heads by “Stages”. You must compare cost, port sizes, valve sizes, total flow data, and the parts themselves.
Valve sizes do dramatically affect flow as well as porting. Stock LS1/LS6 valve sizes are on the order of: 2.00” for the intake and 1.55” for the exhaust. For some good stock head data read here. For some good ported head data comparisons, read here.
As far as comparing CNC LS6 heads vs others, it still depends on the purpose of the CNC port design. The port design could be for out all racing trying to maximize flow at say .700” lift. To accomplish this may hurt low end performance, but for a drag car who cares. However, it would not be realistic to compare a head like that vs. stock LS6 heads because they have two completely different purposes.
The good news is you have tons of choices today and many of them are very affordable. Much of it will depend on your specific objectives and goals.
FYI, we had a set a L92 heads (the heads on the new 6.2L engine) hand ported, and achieved the following results:
HTH
Valve sizes do dramatically affect flow as well as porting. Stock LS1/LS6 valve sizes are on the order of: 2.00” for the intake and 1.55” for the exhaust. For some good stock head data read here. For some good ported head data comparisons, read here.
As far as comparing CNC LS6 heads vs others, it still depends on the purpose of the CNC port design. The port design could be for out all racing trying to maximize flow at say .700” lift. To accomplish this may hurt low end performance, but for a drag car who cares. However, it would not be realistic to compare a head like that vs. stock LS6 heads because they have two completely different purposes.
The good news is you have tons of choices today and many of them are very affordable. Much of it will depend on your specific objectives and goals.
FYI, we had a set a L92 heads (the heads on the new 6.2L engine) hand ported, and achieved the following results:
stock GM valves, we installed new seats and bronze guides, cut the exhaust valve down to a 1.550” valve (suggested by the head porter). Final valve sizes are 2.165” and 1.550”.
Code:
Flow Numbers – SF1020 Bench, 4.125” bore plate Lift Int Exh .100 80 58 .200 155 114 .300 230 151 .400 285 180 .500 325 200 .550 341 210 .600 352 216 .650 360 220 .700 365 226
Former Vendor
Joined: Mar 2006
Posts: 153
Likes: 0
Originally Posted by MattB
Wow, thanks for the infoAnyone want to chime in on the GMPP CNC'ed LS6 heads, a link, some info or comp to AFR 205's?
I made 480rwhp well over 4 years ago with a 383, those heads, and that cam. For most people, it is a bit much in a stock cube motor, but definitely a head turner when you crank it up.
Many people have doubted these heads over the years because of port size, but GM did their homework.There have been some good results with AFR's. They are definitely on the more costly side. Talk to Tony about cam recommendations. They have some specific recommendations that have produced some very nice results.
We sell both.
Melting Slicks
Joined: Jan 2005
Posts: 3,315
Likes: 28
From: Wa
Your set-up
Originally Posted by John@SDPC
GM CNC LS6 Heads These heads plus a Grand Am cam will knock your socks off.
I made 480rwhp well over 4 years ago with a 383, those heads, and that cam. For most people, it is a bit much in a stock cube motor, but definitely a head turner when you crank it up. Many people have doubted these heads over the years because of port size, but GM did their homework.
There have been some good results with AFR's. They are definitely on the more costly side. Talk to Tony about cam recommendations. They have some specific recommendations that have produced some very nice results.
We sell both.
I made 480rwhp well over 4 years ago with a 383, those heads, and that cam. For most people, it is a bit much in a stock cube motor, but definitely a head turner when you crank it up.
Many people have doubted these heads over the years because of port size, but GM did their homework.There have been some good results with AFR's. They are definitely on the more costly side. Talk to Tony about cam recommendations. They have some specific recommendations that have produced some very nice results.
We sell both.
Former Vendor
Joined: Mar 2006
Posts: 153
Likes: 0
Originally Posted by Crabr1
What kind of rwhp are you getting with your set-up on a LS-1.And how much $ for your H/C set-up.I will be in the market for a set real soon.
For instance, a cam + bolt-on f-body with an M6 put down 370/366 with the ASA cam (slightly smaller than the Grand Am). You can also try searching for "ASA" or "Hot Cam". I would say mid 300's with cam only and upper 300's to 420's+ with cam and heads depending on the rest of your setup.
Hot Cam: 219/228 .525/.525 112
ASA Cam: 226/236 .525/.525 110
Grand Am: 239/251 .570/.570 106
We have many kits ranging from ~$400 to $2k+. PM sent.
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Race Director
Joined: Dec 2004
Posts: 13,760
Likes: 75
From: Haymarket VA
Originally Posted by John@SDPC
FYI, we had a set a L92 heads (the heads on the new 6.2L engine) hand ported, and achieved the following results:
stock GM valves, we installed new seats and bronze guides, cut the exhaust valve down to a 1.550” valve (suggested by the head porter). Final valve sizes are 2.165” and 1.550”.
Code:
Flow Numbers – SF1020 Bench, 4.125” bore plate Lift Int Exh .100 80 58 .200 155 114 .300 230 151 .400 285 180 .500 325 200 .550 341 210 .600 352 216 .650 360 220 .700 365 226
