"Cathedral" or Rectangular" Cylinder Heads ?
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Joined: Mar 2013
Posts: 1,137
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From: Studewood/Acres-Homes TX.
used lq9 block
New Eagle 4.0 crank/ 6.125 rod
Bare L92 heads i got back in 08 back then 175 . ea
i'm selling the rod/crank 4 500.ea block 250 heads 250 altogether just needs pistons to get 402 - 408ci LME could do the short block and put the heads together......I have TFS Ls3 heads.. going this mouring to get 4.375/6.640 eagle combo crank 800.oo/ rods 550.oo doing a 479 lsx tall deck short block anybody can have it for 1500 hell 1400. or it just will stay boxed up in the closet. My buddy ROB wants it but i will have 2 wait 4 TAX refund so i got it till @ least March.
New Eagle 4.0 crank/ 6.125 rod
Bare L92 heads i got back in 08 back then 175 . ea
i'm selling the rod/crank 4 500.ea block 250 heads 250 altogether just needs pistons to get 402 - 408ci LME could do the short block and put the heads together......I have TFS Ls3 heads.. going this mouring to get 4.375/6.640 eagle combo crank 800.oo/ rods 550.oo doing a 479 lsx tall deck short block anybody can have it for 1500 hell 1400. or it just will stay boxed up in the closet. My buddy ROB wants it but i will have 2 wait 4 TAX refund so i got it till @ least March.
Last edited by lil john; Feb 11, 2014 at 08:46 AM.
Thread Starter
TECH Enthusiast
Joined: Apr 2010
Posts: 651
Likes: 10
From: North Carolina
Thanks, in advance . . .
Thread Starter
TECH Enthusiast
Joined: Apr 2010
Posts: 651
Likes: 10
From: North Carolina
used lq9 block
New Eagle 4.0 crank/ 6.125 rod
Bare L92 heads i got back in 08 back then 175 . ea
i'm selling the rod/crank 4 500.ea block 250 heads 250 altogether just needs pistons to get 402 - 408ci LME could do the short block and put the heads together......I have TFS Ls3 heads.. going this mouring to get 4.375/6.640 eagle combo crank 800.oo/ rods 550.oo doing a 479 lsx tall deck short block anybody can have it for 1500 hell 1400. or it just will stay boxed up in the closet. My buddy ROB wants it but i will have 2 wait 4 TAX refund so i got it till @ least March.
New Eagle 4.0 crank/ 6.125 rod
Bare L92 heads i got back in 08 back then 175 . ea
i'm selling the rod/crank 4 500.ea block 250 heads 250 altogether just needs pistons to get 402 - 408ci LME could do the short block and put the heads together......I have TFS Ls3 heads.. going this mouring to get 4.375/6.640 eagle combo crank 800.oo/ rods 550.oo doing a 479 lsx tall deck short block anybody can have it for 1500 hell 1400. or it just will stay boxed up in the closet. My buddy ROB wants it but i will have 2 wait 4 TAX refund so i got it till @ least March.
TECH Regular
Joined: May 2011
Posts: 433
Likes: 1
4.1:1
4L60E
4,000+
Terrible
Ceramic coated 1 7/8" with 3" collector into 3" cats, 3" tapering down to 2 1/2".
The cat back is twin stainless 2 1/2" with "x" up front, straight though offset mufflers then twin in twin out straight though resonator.
Car is 2001 Holden Monaro, which is like your 2004 GTO.
Joined: Mar 2007
Posts: 1,145
Likes: 50
From: Saskatchewan, Canada - where arguing "DA" is for the slow and weak...
Hmm . . . CNC-ported LS2 #799 Cathedral Ports at $550 per head . . .
https://sdparts.com/details/scoggin-...er/x88958765-2
That SURE sounds better than dropping $2300 - $2700, or more, on aftermarket heads, in terms of "bang for the buck", for my application !
https://sdparts.com/details/scoggin-...er/x88958765-2
That SURE sounds better than dropping $2300 - $2700, or more, on aftermarket heads, in terms of "bang for the buck", for my application !
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Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
CompCam 231 239 .617 .624 113
4.1:1
4L60E
4,000+
Terrible
Ceramic coated 1 7/8" with 3" collector into 3" cats, 3" tapering down to 2 1/2".
The cat back is twin stainless 2 1/2" with "x" up front, straight though offset mufflers then twin in twin out straight though resonator.
Car is 2001 Holden Monaro, which is like your 2004 GTO.
4.1:1
4L60E
4,000+
Terrible
Ceramic coated 1 7/8" with 3" collector into 3" cats, 3" tapering down to 2 1/2".
The cat back is twin stainless 2 1/2" with "x" up front, straight though offset mufflers then twin in twin out straight though resonator.
Car is 2001 Holden Monaro, which is like your 2004 GTO.
Nice cam by the way, I was looking at something similar for mine, is yours LS1 (346ci)? What heads?
Teching In
Joined: Jun 2005
Posts: 36
Likes: 1
From: Little Rock, AR
I have been reading this post but unable to respond until today so here is my .02$. If you are going to cam your car and have an auto tranny...forget good gas mileage. I see you are wanting HP in the range of 400-450. You can get any LS1 into the 400 range, but hitting 450 will be some work. IMO, I would say get a LS3 and forge and stroke it. I am pushing 476hp and 468 TQ thru untouched 243 heads (trunion upgrade included) and my stock intake manifold/TB through a RPM trans and Vig 3K stall. I have 450lbs of tq from 3200rpm up. Now my cam is crazy large, but I plan on max effort after I do some suspension upgrades and rear end upgrades. I have read so many articles about cat vs rect heads and on every test, the rect heads gave more HP up top...but barely and was lower in TQ than the cat heads. Most were lower in HP/TQ in the lower rpm range also. I think ls3 heads are fine, but I am sticking with cats...well because I like TQ and I drive a heavy *** GTO. Lastly...Please get what you want...NOW. Nothing worse than going through all the hard work and labor to only wish you had done something else. Good luck.
Thread Starter
TECH Enthusiast
Joined: Apr 2010
Posts: 651
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From: North Carolina
If you are going to cam your car and have an auto tranny...forget good gas mileage.
I see you are wanting HP in the range of 400-450. You can get any LS1 into the 400 range, but hitting 450 will be some work. IMO, I would say get a LS3 and forge and stroke it.
I have read so many articles about cat vs rect heads and on every test, the rect heads gave more HP up top...but barely and was lower in TQ than the cat heads. Most were lower in HP/TQ in the lower rpm range also. I think ls3 heads are fine, but I am sticking with cats...well because I like TQ and I drive a heavy *** GTO. Lastly...
I see you are wanting HP in the range of 400-450. You can get any LS1 into the 400 range, but hitting 450 will be some work. IMO, I would say get a LS3 and forge and stroke it.
I have read so many articles about cat vs rect heads and on every test, the rect heads gave more HP up top...but barely and was lower in TQ than the cat heads. Most were lower in HP/TQ in the lower rpm range also. I think ls3 heads are fine, but I am sticking with cats...well because I like TQ and I drive a heavy *** GTO. Lastly...
Let me ask you a few questions . . .
(1) Why would a 4-speed automatic be so terrible on gas ?
I would be using a lock-up torque converter, stock or near-stock gearing, and a larger displacement motor 408 stroker (42 more cubes than stock ), with a fairly mild profile. Typically, I would only expect a 1-2 mpg difference.
(2) I haven't heard of people using Cathedral heads on an LS3 motor, stock or stroker. I realize they would "fit", but am curious about how that combination would perform.
(3) I would like to resolve the Cathedral vs Rectangular port head question, for my particular application . . . Thoughts ?
Everyone is welcome to chime in !
TECH Regular
Joined: May 2011
Posts: 433
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Since your local, in Australia, I'll give you the fuel consumption in litres/100k's.
Driving in the country gives about 15.5 l/100k, driving in traffic to work is about 30l/100k's.
Surprisingly driving down to the track, racing and driving home usually averages at 25l/100k's
Teching In
Joined: Jun 2005
Posts: 36
Likes: 1
From: Little Rock, AR
Let me ask you a few questions . . .
(1) Why would a 4-speed automatic be so terrible on gas ?
I would be using a lock-up torque converter, stock or near-stock gearing, and a larger displacement motor 408 stroker (42 more cubes than stock ), with a fairly mild profile. Typically, I would only expect a 1-2 mpg difference.
(2) I haven't heard of people using Cathedral heads on an LS3 motor, stock or stroker. I realize they would "fit", but am curious about how that combination would perform.
(3) I would like to resolve the Cathedral vs Rectangular port head question, for my particular application . . . Thoughts ?
Everyone is welcome to chime in !
(1) Why would a 4-speed automatic be so terrible on gas ?
I would be using a lock-up torque converter, stock or near-stock gearing, and a larger displacement motor 408 stroker (42 more cubes than stock ), with a fairly mild profile. Typically, I would only expect a 1-2 mpg difference.
(2) I haven't heard of people using Cathedral heads on an LS3 motor, stock or stroker. I realize they would "fit", but am curious about how that combination would perform.
(3) I would like to resolve the Cathedral vs Rectangular port head question, for my particular application . . . Thoughts ?
Everyone is welcome to chime in !
Check on the below links for a couple of test I found online.
http://www.gmhightechperformance.com...discharge.html
http://www.hotrod.com/techarticles/e...der_head_test/
Thread Starter
TECH Enthusiast
Joined: Apr 2010
Posts: 651
Likes: 10
From: North Carolina
Teching In
Joined: Jun 2005
Posts: 36
Likes: 1
From: Little Rock, AR
Teching In
Joined: Sep 2009
Posts: 28
Likes: 0
From: Sydney, Australia
Staging Lane
Joined: Jul 2009
Posts: 85
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hey Sinister, if you want a really well built stock LY6 block with LS3 heads, contact Rick Crawford (G8-4-Speed on here). He has stock bottom end G8's in the 10's (that's a two ton grocery getter for those keeping score) on all motor setups. He does head work, specs cams and tuning. Give him a jingle and I bet he can get you to your goals without spending an *** load of cash.
Staging Lane
Joined: Jul 2009
Posts: 85
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I told you in my first reply to this thread, flow #'s don't mean everything. Both heads work, and have their places.
(2) I haven't heard of people using Cathedral heads on an LS3 motor, stock or stroker. I realize they would "fit", but am curious about how that combination would perform.
(3) I would like to resolve the Cathedral vs Rectangular port head question, for my particular application . . . Thoughts ?
Everyone is welcome to chime in !
Ray Bulach (Fastest 6 speed shifted F-body, Blu99fbody on the board) Ran TFS cathedral port heads on his 416, running 8.80's in the quarter.
There's A LOT of other guys running it as well. It sets records, it performs great. LOL. The rect-port heads are no slouch either though, motor just has to be set up for them as far as cam/intake goes. Look at Dietcoke's thread, LS7 build results with just porting, etc. Some guys just have preference or already have parts to go with the style of head so they stick with it.
For your "particular application" as far as DD worthy street car. I still stick by suggesting cathedral port heads. But thats just me. They have a nice power band. I realllllllllly don't think you can go "wrong" with either one. This subject has been beaten to death over the past few years. Tons of threads pertaining to velocity, port size/shape, valve size, CC design, valve shrouding, blah blah. I'd just buy what fits your budget. Doesn't seem like your number hunting or building a strip car so I think you'll be happy whatever you pick. Just get the right cam.
---On a side-note. TFS does have their new LS3 rect port offering that flows surprisingly well. I was quite tempted to pick up a set of those.
Last edited by SinisterWS6; Feb 14, 2014 at 02:39 AM.
SinisterWS6 nailed it. Look for the best CFM out of the smallest intake port & valve, and compare the bore fixture size as well, ideally matching it to yours... or realize that larger fixtures will increase the numbers. Flow at .700 doesn't mean much if your valve lift is only .600... you just don't want it falling over after .600.
The cathedral ports have better air velocity for torque & throttle reponse. For cathedral, consider the TFS GenX 235 or AFR 230, or the AFR 245 if your bore is large enough. The Fast 102 intake is probably the most popular for big budgets... you won't be leaving anything on the table except a lighter wallet.
For rectangular ports, consider the TFS GenX 255, Mast 256, or PRC 255/260's. Then send a used LS3 manifold to Rick Crawford to get his modified version of the intake with radius bars if you want equal performance to the ported Fast 102 for a lot less money.
I personally don't see enough bang for the buck in the non-OEM LS3 heads to warrant me switching from OEM LS3 heads & the RC intake. I have info from a big sponsor who has seen numerous ported stock LS3 castings and aftermarkets as well, and basically said I'm better off porting a stock casting and/or milling for compression; make up the torque in the cam profile, get compression to 11.5, don't go too big on the longtube primaries, etc. But my goals are not necessarily yours... I don't want to spend $1500-$3500 on a set of heads which basically only gives me gains above 3000RPM on a torquey street car... and maybe a peak of 30rwhp above 6000RPM in a range I rarely visit.
The cathedral ports have better air velocity for torque & throttle reponse. For cathedral, consider the TFS GenX 235 or AFR 230, or the AFR 245 if your bore is large enough. The Fast 102 intake is probably the most popular for big budgets... you won't be leaving anything on the table except a lighter wallet.
For rectangular ports, consider the TFS GenX 255, Mast 256, or PRC 255/260's. Then send a used LS3 manifold to Rick Crawford to get his modified version of the intake with radius bars if you want equal performance to the ported Fast 102 for a lot less money.
I personally don't see enough bang for the buck in the non-OEM LS3 heads to warrant me switching from OEM LS3 heads & the RC intake. I have info from a big sponsor who has seen numerous ported stock LS3 castings and aftermarkets as well, and basically said I'm better off porting a stock casting and/or milling for compression; make up the torque in the cam profile, get compression to 11.5, don't go too big on the longtube primaries, etc. But my goals are not necessarily yours... I don't want to spend $1500-$3500 on a set of heads which basically only gives me gains above 3000RPM on a torquey street car... and maybe a peak of 30rwhp above 6000RPM in a range I rarely visit.