speedmaster (Pro Comp) Ls7 6 bolt castings
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Figure of speak for the Dumb part. But if guys think a bigger* lower runner* 15 degree head* is better than a smaller* higher runner* 12 degree head. Funny I own both and have asked and did have it made because of what I learned as I didn't even need a Ls7 head to be honest. I LOVE CYLINDER HEADS SO........No harm no foul. If I could get a valve made cheaper than $1k..... It's Lsx-R heads or LSX CT heads for a 408...LMAO also! Sold a pair on the 1st one listed guy went broke I bought them held them for 8 months and Jim help me sell them as he's the one who sold the guy the heads from the shop. Anybody need a aluminum 5.3 block for resleeve. Don't need it I can make big cubic inch numbers with a 408.
Thanks for the numbers Patron. Like you, I’ve been into cylinder heads since I was very young. I ported my own heads on my race atv’s before I had a drivers license. I aspired to own my own cylinder head shop, but found myself earning a living, owning an electrical contracting company at 25. I worked for a shop that built cup engines in the early 90’s, and I built myself a set of $10k Brodix heads for a sbc that I still have today. I study this stuff constantly. It’s a passion.
I’m impressed with the ProComp units here, and I agree with you concerning lifters. Don’t skimp, especially with a race application.
Today’s hollow steel valve technology is incredible. I’d not go with titanium valves unless I was willing (and financially able) to change them regularly. Titanium has a short life span. This is why you see so many used sets for sale on race equipment sites.
This thread is full of great info.
I’m impressed with the ProComp units here, and I agree with you concerning lifters. Don’t skimp, especially with a race application.
Today’s hollow steel valve technology is incredible. I’d not go with titanium valves unless I was willing (and financially able) to change them regularly. Titanium has a short life span. This is why you see so many used sets for sale on race equipment sites.
This thread is full of great info.
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Yea I'd have had G Good do a set of Lsx CT heads for a 4.030 bore about 4 or 5 yrs ago but the damn titanium valves with the cost of everything else stopped me. The Lsx R is the same way. They won't make a hollow stem valve for me and really can't as it's would be weaker being that it's so long and a stainless steel valve would be to heavy.
Here's the length for GM Lsx CT valves: 6.350 vs a ls7 intake valve of 5.130 or so.
Here's the length for GM Lsx CT valves: 6.350 vs a ls7 intake valve of 5.130 or so.
A thinner part of a combustion chamber will run hotter and can cause single cylinder detonation issues that baffled the HELL out of the “tunnel port” guys from Ron Niel’s Prototype Racing Engines back in the day,till Ol’ Smokey figured that **** out for them.
Sure those things have a great shape and runner size, prolly can flow like all get up, but in the real world, potential don’t mean squat
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Chambers are not thin Bowls are a little thin as Darin just put one in the Cnc. We've got guys here running Pro Comp Ls3 & Ls7 heads and no issues. The few who had problems are the same thing with the sorry rocker arms and guides as with other Ls7 heads factory is not limited do a search and others with aftermarket heads Ls7 have had the same problem. I milled off around .048 to go from 70 cc to 61 cc's on Pro Comp castings. I'd recommend doing the pistons to get compression up I'd just swap heads and go from 11.6 to around 12.9 as the Ls3 heads are 70 cc's.
Quote from another thread:
You wanna hear a good joke....this is for the guys over on the other thread about Pro Comp Ls7 heads who know heads. Look at what a MAST Ls3 12 degree head did VS factory Ls3 heads. So funny. All or most Ls7 heads in the Ls7 heads test were within reason.
__________________
Quote from another thread:
You wanna hear a good joke....this is for the guys over on the other thread about Pro Comp Ls7 heads who know heads. Look at what a MAST Ls3 12 degree head did VS factory Ls3 heads. So funny. All or most Ls7 heads in the Ls7 heads test were within reason.
__________________
Last edited by Patron; Jan 15, 2018 at 09:17 PM.
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From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
Chevelle you want data ....Ls7 heads test.
We baselined the engine with factory GM LS7 castings. Four of the heads we tested were stock castings that had been CNC-ported by GM Performance Parts, Lingenfelter Performance Engineering, Texas Speed, and Scoggin-Dickey Performance Center (SDPC). We also checked out the CNC-ported versions of the dedicated castings from Procomp Electronics, Mast Motorsports, and Texas Speed. All were run with appropriate valve springs and factory LS7 rocker arms. We verified that all had 70cc combustion chambers.
Conclusions
There wasn’t a dog in this bunch. There is a sizable gap in price between the most expensive and least expensive heads, but they all made big power. There was greater variance than what we saw in our LS3 test (where every head tested made virtually the same power), but in reviewing the numbers, we had to ask ourselves what the real difference in e.t. or seat-of-the-pants feel would be between the 13.5 average horsepower and 12.9 average torque numbers that separate the lowest-priced heads and the biggest-power heads we tested.
We were also interested to note that, in general, the heads with the better flow numbers produced better power, as you’d expect. But the flow bench does not tell the whole story; looking at flow alone, you might not select the SDPC heads, yet they outpowered some of the heads with similar or slightly higher flow numbers. There’s still some magic in port and chamber shapes.
Bottom Line:
Every LS7-based head is amazing. The Procomp heads clearly win the low-price contest, using import castings and domestic porting to make more power at a lower price than even the stock LS7 heads. Judging by the average power numbers, the Texas Speed PRC heads seem to offer the best value, and the Mast Black Label heads crank out the highest power.
GMPP 270ccc heads: peak Hp/tq 773 @ 6300 and 704 @ 4700
ProComp 265cc heads 785 @ 6400 and 716 @ 5100 needs some handy port work!!!!
Lingenfelter 275 ccheads 793 @ 6500 and 719 @ 5300
TSP/PRC 285cc heads 796 @ 6300 and 725 @ 5200
TSP GMPP 265cc heads 799 @ 6500 and 714 @ 5300
SDPC Ls7 heads 802 @ 6500 and 717 @ 5500
Mast 274 cc heads 810 @ 6600 and 726 @ 5300
We baselined the engine with factory GM LS7 castings. Four of the heads we tested were stock castings that had been CNC-ported by GM Performance Parts, Lingenfelter Performance Engineering, Texas Speed, and Scoggin-Dickey Performance Center (SDPC). We also checked out the CNC-ported versions of the dedicated castings from Procomp Electronics, Mast Motorsports, and Texas Speed. All were run with appropriate valve springs and factory LS7 rocker arms. We verified that all had 70cc combustion chambers.
Conclusions
There wasn’t a dog in this bunch. There is a sizable gap in price between the most expensive and least expensive heads, but they all made big power. There was greater variance than what we saw in our LS3 test (where every head tested made virtually the same power), but in reviewing the numbers, we had to ask ourselves what the real difference in e.t. or seat-of-the-pants feel would be between the 13.5 average horsepower and 12.9 average torque numbers that separate the lowest-priced heads and the biggest-power heads we tested.
We were also interested to note that, in general, the heads with the better flow numbers produced better power, as you’d expect. But the flow bench does not tell the whole story; looking at flow alone, you might not select the SDPC heads, yet they outpowered some of the heads with similar or slightly higher flow numbers. There’s still some magic in port and chamber shapes.
Bottom Line:
Every LS7-based head is amazing. The Procomp heads clearly win the low-price contest, using import castings and domestic porting to make more power at a lower price than even the stock LS7 heads. Judging by the average power numbers, the Texas Speed PRC heads seem to offer the best value, and the Mast Black Label heads crank out the highest power.
GMPP 270ccc heads: peak Hp/tq 773 @ 6300 and 704 @ 4700
ProComp 265cc heads 785 @ 6400 and 716 @ 5100 needs some handy port work!!!!
Lingenfelter 275 ccheads 793 @ 6500 and 719 @ 5300
TSP/PRC 285cc heads 796 @ 6300 and 725 @ 5200
TSP GMPP 265cc heads 799 @ 6500 and 714 @ 5300
SDPC Ls7 heads 802 @ 6500 and 717 @ 5500
Mast 274 cc heads 810 @ 6600 and 726 @ 5300
http://www.hotrod.com/articles/hrdp-...top-ls7-heads/
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Yea I tried reading it on the computer but it hurt my eyes.....I have the mag itself. Also they didn't write it like with the Ls3 heads it's just a photo which is Hard to see and I C Damn good.
1 interesting thing is I looked at Mast small bore Ls7 heads which I know is Correct for cfm and other things *also a better head, and not inflated #'s*. As well as TSP small bore with other Cnc programs. Even the ProComp casting in the same article. Here's what I read & learned cheap heads with a good porter have better under the curve cfm. To the young man who started the thread this confirms what I told you buy the heads Cnc'ed and work it to get low and mid lift #'s up = short side radius and bowls. Easier and quicker. If you read below I've looked a Mast 265 heads the runners is about the same with mine the bowls with the larger valve is what adds more CC.
Mine are 275cc / 265cc Pro Comp cnc and tested on a 4.125 bore vs 4.060 used
0.2000 165.2 158
0.3000 238.7 225
0.4000 300.6 301
0.5000 336.2 337
Side note as I've posted this before Brodix heads on basically the same 495 engine as these magazines are all tied together Super Chevy, Hot Rod, *Popular Hot Rodding old & gone but was the Best magazine published* along with GMHTP gone also.
STS BR7 273 heads from Brodix made 799 hp @ 6500 and 714 tq @ 5300. Work a cheap head and your there also LMAO!
http://www.superchevy.com/how-to/eng...ylinder-heads/
1 interesting thing is I looked at Mast small bore Ls7 heads which I know is Correct for cfm and other things *also a better head, and not inflated #'s*. As well as TSP small bore with other Cnc programs. Even the ProComp casting in the same article. Here's what I read & learned cheap heads with a good porter have better under the curve cfm. To the young man who started the thread this confirms what I told you buy the heads Cnc'ed and work it to get low and mid lift #'s up = short side radius and bowls. Easier and quicker. If you read below I've looked a Mast 265 heads the runners is about the same with mine the bowls with the larger valve is what adds more CC.
Mine are 275cc / 265cc Pro Comp cnc and tested on a 4.125 bore vs 4.060 used
0.2000 165.2 158
0.3000 238.7 225
0.4000 300.6 301
0.5000 336.2 337
Side note as I've posted this before Brodix heads on basically the same 495 engine as these magazines are all tied together Super Chevy, Hot Rod, *Popular Hot Rodding old & gone but was the Best magazine published* along with GMHTP gone also.
STS BR7 273 heads from Brodix made 799 hp @ 6500 and 714 tq @ 5300. Work a cheap head and your there also LMAO!
http://www.superchevy.com/how-to/eng...ylinder-heads/
Last edited by Patron; Jan 16, 2018 at 02:22 PM.
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