Cathedral vs ls3 test on a 408
Thread Starter
10 Second Club
Joined: May 2009
Posts: 3,427
Likes: 226
From: over dere
Sorta poking the bear with this. CSA is pretty important and every port has to make a turn as it approaches the valve. A raised floor higher ceiling makes for a longer runner which pours more CCs but carries a straighter shot at the back of the valve The CSA tends to dictate the runner's velocity which creates tumble and turbulence thus keeping fuel particles small and atomized. Better quicker faster burn kernel Less emotions cleaner. More powerful
Today's direct injection no longer gives a darn what the runner is shaped like from the swirl standpoint
It's kind of hard to answer that question since it depends a whole lot on the car it's in. Here's another question. Is this engine making the power it should? It's 408 inches, has a pretty big cam, a $1000 intake manifold, no exhaust system to speak of, an electric water pump, and zero accessories. It made 580 fwhp, which is 493 whp assuming 15% loss. Seems a little weak to me, especially assuming that if it were in a car it would have more parasitic losses. Maybe I just don't understand engines.
You mean this one... 
http://www.hotrod.com/articles/ccrp-...re-port-heads/
I would rather have the AFR 245 or something of an equivalent in a cathedral port on a 408
http://www.hotrod.com/articles/ccrp-...re-port-heads/
I would rather have the AFR 245 or something of an equivalent in a cathedral port on a 408
TECH Veteran
Joined: Sep 2014
Posts: 4,893
Likes: 703
From: Mississippi
It's kind of hard to answer that question since it depends a whole lot on the car it's in. Here's another question. Is this engine making the power it should? It's 408 inches, has a pretty big cam, a $1000 intake manifold, no exhaust system to speak of, an electric water pump, and zero accessories. It made 580 fwhp, which is 493 whp assuming 15% loss. Seems a little weak to me, especially assuming that if it were in a car it would have more parasitic losses. Maybe I just don't understand engines.
WARNING!! It's a buddie of mine that no longer posts here but still is a member that owns a ws6 that runs 10.4s on motor with a 6 speed. Yes it's 3700 lbs with the driver with leather seats,radio, heater, etc...
Yes it's pump gas with a hydraulic roller also. Just a simple combo. No single plane or LLSR bulls#it eithier.
Hell he went 10.4s on a M&H tire that wasn't even a full slick.
I honestly think the car will go faster on a full stiff wall slick. We all know 6 speed cars needs a great tire for traction. Then again if the motor was in a lighter camaro I could see a 10.3 with ease.
Someone show me better..... ANYBODY!!
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo TECH Veteran
Joined: Sep 2014
Posts: 4,893
Likes: 703
From: Mississippi
You mean this one...
http://www.hotrod.com/articles/ccrp-...re-port-heads/
I would rather have the AFR 245 or something of an equivalent in a cathedral port on a 408
http://www.hotrod.com/articles/ccrp-...re-port-heads/
I would rather have the AFR 245 or something of an equivalent in a cathedral port on a 408
the AFR made more power even with a cam that was speced for LS3 heads. The same exact cam mentioned earlier. I've seen AFR heads do well even with a single pattern camshaft. 
Banned
Joined: Apr 2017
Posts: 948
Likes: 1
Hmmmm.... Looky, Looky what I've found. Don't get on as much but let's touch some bases for some of the BS.
1st: By Spanks13
Let me know when a Cathedral head gets 3.2 + CSA, so go in a corner and think about that one for just 1 sec. Let me know what you come back with!
1st: By Spanks13
Fake news.
If the CSA is the same why does the engine care if the port is a rectangle or shaped like a urinal?
If the CSA is the same why does the engine care if the port is a rectangle or shaped like a urinal?
Let me know when a Cathedral head gets 3.2 + CSA, so go in a corner and think about that one for just 1 sec. Let me know what you come back with!
Banned
Joined: Apr 2017
Posts: 948
Likes: 1
The only thing this showed me is how much port work Works! I know of Factory Ls2 style heads putting in work as with Ls3's. Bigger valve Ls2 2.100. You can make anything work with simple Common Sense. The same head that made the least with some common sense could be just as good as the aftermarket cheaper. Believe I've said this before. Replace the factory Ls3 heads with a good Ls3 Cnc program and what then. It's about even.
Best post here Reads:
The Cathedral and Ls3 both have lower lying runners* the Key difference in Ls7 heads.* Yet I can say that the Factory Ls3 heads can make 500 ft lbs and is enough head for 850ish + depending on CID. But that's a well known fact. So Y buy a aftermarket head if it's not a Ls7. Sounds like a waste of $. Heres FACTORY cathedral heads letting off some steam. So powers just in the eye of the the beholder. LMAO!!!!
https://ls1tech.com/forums/dynamomet...-601-rwhp.html
https://www.corvetteforum.com/forums...g-results.html
1 more thing I see and read a lot: CC's and heads.
Ls7 heads reads 275 cc's
Vs
FRH Ls3 stage 1 heads 268 cc's
Which has the Larger CSA? If the Ls7 heads are thought to be bigger...Wrong! CC's honestly tells me nothing UNLESS we are using the same style heads. The quote above tells you why the Ls7 heads has a smaller CSA yet more CC volume. Don't Say what the Factory Can't do!
Best post here Reads:
Sorta poking the bear with this. CSA is pretty important and every port has to make a turn as it approaches the valve. A raised floor higher ceiling makes for a longer runner which pours more CCs but carries a straighter shot at the back of the valve The CSA tends to dictate the runner's velocity which creates tumble and turbulence thus keeping fuel particles small and atomized. Better quicker faster burn kernel Less emotions cleaner.
https://ls1tech.com/forums/dynamomet...-601-rwhp.html
https://www.corvetteforum.com/forums...g-results.html
1 more thing I see and read a lot: CC's and heads.
Ls7 heads reads 275 cc's
Vs
FRH Ls3 stage 1 heads 268 cc's
Which has the Larger CSA? If the Ls7 heads are thought to be bigger...Wrong! CC's honestly tells me nothing UNLESS we are using the same style heads. The quote above tells you why the Ls7 heads has a smaller CSA yet more CC volume. Don't Say what the Factory Can't do!
Last edited by Patron; Oct 22, 2017 at 06:42 AM.
Well most guys on here own a F body and 408 motors are now common. I don't really care about dyno numbers eithier. Dynos are just a tuning tool and that's it in my opinion. I'm being realistic here... I want to see some 40X cubic inch cars with LS3 heads of any brand with a hydraulic roller on pump gas track results. Automatic or 6 Speed..... it doesn't matter to me. Mph/e.t never lie.
WARNING!! It's a buddie of mine that no longer posts here but still is a member that owns a ws6 that runs 10.4s on motor with a 6 speed. Yes it's 3700 lbs with the driver with leather seats,radio, heater, etc...
Yes it's pump gas with a hydraulic roller also. Just a simple combo. No single plane or LLSR bulls#it eithier.
Hell he went 10.4s on a M&H tire that wasn't even a full slick.
I honestly think the car will go faster on a full stiff wall slick. We all know 6 speed cars needs a great tire for traction. Then again if the motor was in a lighter camaro I could see a 10.3 with ease.
Someone show me better..... ANYBODY!!
WARNING!! It's a buddie of mine that no longer posts here but still is a member that owns a ws6 that runs 10.4s on motor with a 6 speed. Yes it's 3700 lbs with the driver with leather seats,radio, heater, etc...
Yes it's pump gas with a hydraulic roller also. Just a simple combo. No single plane or LLSR bulls#it eithier.
Hell he went 10.4s on a M&H tire that wasn't even a full slick.
I honestly think the car will go faster on a full stiff wall slick. We all know 6 speed cars needs a great tire for traction. Then again if the motor was in a lighter camaro I could see a 10.3 with ease.
Someone show me better..... ANYBODY!!
Banned
Joined: Apr 2017
Posts: 948
Likes: 1
That's pretty Easy a 10.4 on a 1/4 track would or may need a gear change and would be around 6.2 to 6.5 on a 1/8 th mile track. Same car that weighed in @ 3700 if gotten down to 3300 or less would be around a higher 9 sec 1/4 mile or a 5 second pass in the 8th of a mile. Every 100 lbs less = .1 off of a a pass typically.
Hammer: besides NA the dope motored Ls3 heads make some HP also. Jim's LQ 408 with Ls3 heads was set up with a Hyd roller and Dome Top pistons 14:5 comp and a 400 shot =1000 easy at the crank. On motor it made 660'ish never tried the the shot...Jim Sold everything said everyone has a Ls swap and kept the BBC in the Camaro. 800 on motor and the same shot. ER racing with a shot would be around 1k also 800hp needs only a good pill. With factory heads mine you. You can make anything work. Dope/Nos motors like more CSA.
Hammer: besides NA the dope motored Ls3 heads make some HP also. Jim's LQ 408 with Ls3 heads was set up with a Hyd roller and Dome Top pistons 14:5 comp and a 400 shot =1000 easy at the crank. On motor it made 660'ish never tried the the shot...Jim Sold everything said everyone has a Ls swap and kept the BBC in the Camaro. 800 on motor and the same shot. ER racing with a shot would be around 1k also 800hp needs only a good pill. With factory heads mine you. You can make anything work. Dope/Nos motors like more CSA.
Last edited by Patron; Oct 22, 2017 at 12:15 PM.
Banned
Joined: Apr 2017
Posts: 948
Likes: 1
Just a ballpark to give reference. 6.6 to 6.7 from a typical 10.4 pass. To be More precise. Ballparking is a MF'er not even knowing darn close off the top of the head.
Last edited by Patron; Oct 22, 2017 at 12:37 PM.
TECH Veteran
Joined: Sep 2014
Posts: 4,893
Likes: 703
From: Mississippi
Car first time out went 10.61@ 131 with a lingenfelter 100 MAF on a M&H cheater slick.
Changes- he ditched the MAF for a speed density tune and tweaked his 60ft by playing with suspension and installing a BMR xtreme rear drag bar. Results was a 10.4 on motor. Again that's pretty good for a 11.5 compression 402ci car with TEA TFS 235s right out the box, Mamo ported 102mm FAST intake and a pat G cam. Car made 545 rwhp on a mustang dyno.
Changes- he ditched the MAF for a speed density tune and tweaked his 60ft by playing with suspension and installing a BMR xtreme rear drag bar. Results was a 10.4 on motor. Again that's pretty good for a 11.5 compression 402ci car with TEA TFS 235s right out the box, Mamo ported 102mm FAST intake and a pat G cam. Car made 545 rwhp on a mustang dyno.