Head Performance
04-15-2007, 11:52 AM
#2
Originally Posted by KAOS
which heads perform better l92 or the ls7's? i know that the l92s have great flow numbers and make good power but ive yet to see a whole lot of results out of a set of ported ls7 heads... so any info would be great
04-17-2007, 07:27 PM
#4
Originally Posted by KAOS
so stock ls7s are that much more? why i wonder? and that is bare?
There are some interesting options in the GM Perf Parts catalog, like CNC ported LS7 heads...
04-18-2007, 06:46 AM
#5
The standard LS7 head is already CNC ported. Flows around 360-370 cfm at .600. They also have a better chamber than the L92's. However they are not cheap. they do offer a as cast head for a little cheaper, but to be quite honest with you, I really don't think you can beat the factory CNC port for a vehicle that will be on the street any.
Trending Topics
04-19-2007, 10:50 PM
#10
11 Second Club
Originally Posted by KAOS
what is the cost?
04-20-2007, 11:00 AM
#12
11 Second Club
Originally Posted by KAOS
im assuming this is for the et ls7's right?
Originally Posted by KAOS
what is the cost for gm ls7's? how hard is it to do a 4.1 bore?
Originally Posted by KAOS
will a stock iron block do it? or ls2 block or l92?
If money is a concern then you can't beat the L92 heads for bang for the buck. If money is not a deciding factor then IMO the ETP LS7 heads with a LS7 intake is the cream of the crop (so to speak).
04-20-2007, 11:41 AM
#13
GM LS7 castings are ~$1800 for the CNC ported castings and ~$2500 for the assembled heads. Remember, on the assembled heads, the factory TI valves have issues, and the springs are only good up to .600. So make you choices wisely..
FWIW The factory LS7 intake is by far the best composite intake available, however, to keep up with a 454 ci motor, you may need some more...... Adjust cost accordingly.
What would this motor be going in? What do you want out of it? How much money do you want to spend?
FWIW The factory LS7 intake is by far the best composite intake available, however, to keep up with a 454 ci motor, you may need some more...... Adjust cost accordingly.
What would this motor be going in? What do you want out of it? How much money do you want to spend?
04-23-2007, 03:23 PM
#14
On The Tree
iTrader: (4)
Join Date: Jun 2006
Location: Texas / 427ci F1R 1,002 rwhp/928 rwtq
Posts: 197
Likes: 0
Received 0 Likes
on
0 Posts
Suppose the ported L92's flowed almost as well as the LS7's (I think some are almost as good), do you think the LS7 intake will produce more power in a FI application (SC or TT)?
04-23-2007, 03:27 PM
#15
John, the power potential difference between the L92's and the LS7's is more than just the amount they will flow. From what I can gather, the L92 just doesn't have the meat in it to really lay down the numbers to compete with the LS7 head.
I honestly believe we have just seen the tip of the iceberg on these heads. (both of them)
I honestly believe we have just seen the tip of the iceberg on these heads. (both of them)
04-23-2007, 03:31 PM
#16
Originally Posted by john_sblendorio
Suppose the ported L92's flowed almost as well as the LS7's (I think some are almost as good), do you think the LS7 intake will produce more power in a FI application (SC or TT)?
04-23-2007, 05:21 PM
#17
TECH Fanatic
Join Date: Mar 2004
Location: Laguna Niguel, CA
Posts: 1,017
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Stang's Bane
John, the power potential difference between the L92's and the LS7's is more than just the amount they will flow. From what I can gather, the L92 just doesn't have the meat in it to really lay down the numbers to compete with the LS7 head.
I honestly believe we have just seen the tip of the iceberg on these heads. (both of them)
I honestly believe we have just seen the tip of the iceberg on these heads. (both of them)
Do you mean not enough physical aluminum to do a good port?
And do you think we have seen the end of the cathedral ports in favor of the square ports?
04-24-2007, 08:33 AM
#18
Originally Posted by gun5l1ng3r
What do you mean by the L92's not having the meat on them?
Do you mean not enough physical aluminum to do a good port?
And do you think we have seen the end of the cathedral ports in favor of the square ports?
Do you mean not enough physical aluminum to do a good port?
And do you think we have seen the end of the cathedral ports in favor of the square ports?
The flow numbers are definitely important, but not #1 unless you have a 400 inch SBC with double humps.
The better the head, the less the flow numbers matter for overall performance. There are guys that have SB2 heads they claim flow 450+CFM. If they flow that much, good for them. The heads on the car leading the most laps at Phoenix on saturday don't flow anywhere near 450, but they are as big volume-wise as the 450 CFM heads. The fast running heads have proper geometry with a properly shaped flow curve. What I mean by properly shaped flow curve isn't internet info, but I can say the flow curve will look a certain way when the port geometry is right; along with the valvejob. If it could be explained on the internet in it's entirety anyone could do race-winning heads.
I have seen two identical heads (CNC program) make quite different power because of the valvejob only. The heads that make more power would appear completely inferior to most people because they don't have a "lot of area under the curve".
Extremely poor heads like a pontiac need raw flow numbers because the port and chamber are so horrendous they will never have enough intertia to make power. I think it takes a good guy to make a head like that run.
Pro Stock on the extreme opposite side, will be almost entirely geometry specific to making power. There are things on these heads guys do that hurt flow tremendously that picks up a bunch of power. If a Pro Stock engine builder bought heads the way most people do on the internet they would never qualify, I guarantee it.
The better the head, the less the flow numbers matter for overall performance. There are guys that have SB2 heads they claim flow 450+CFM. If they flow that much, good for them. The heads on the car leading the most laps at Phoenix on saturday don't flow anywhere near 450, but they are as big volume-wise as the 450 CFM heads. The fast running heads have proper geometry with a properly shaped flow curve. What I mean by properly shaped flow curve isn't internet info, but I can say the flow curve will look a certain way when the port geometry is right; along with the valvejob. If it could be explained on the internet in it's entirety anyone could do race-winning heads.
I have seen two identical heads (CNC program) make quite different power because of the valvejob only. The heads that make more power would appear completely inferior to most people because they don't have a "lot of area under the curve".
Extremely poor heads like a pontiac need raw flow numbers because the port and chamber are so horrendous they will never have enough intertia to make power. I think it takes a good guy to make a head like that run.
Pro Stock on the extreme opposite side, will be almost entirely geometry specific to making power. There are things on these heads guys do that hurt flow tremendously that picks up a bunch of power. If a Pro Stock engine builder bought heads the way most people do on the internet they would never qualify, I guarantee it.
As far as the last question. Within the next couple of years, I believe GM will quit producing the cathedral port heads for performance applications. Hell, after this year even, if the LS3 is what I think it is...
