Cathedral Port Vs. Rectangular Port
Which is why I'm hoping it really shines in my combo. 
It'll be interesting I think. I believe we're both doing tight lash solid rollers.
My biggest issue right now is figuring out what manifold to run. I've got 3 to choose from, and apparently NONE of them can get their **** together yet.
It'll be interesting I think. I believe we're both doing tight lash solid rollers.
My biggest issue right now is figuring out what manifold to run. I've got 3 to choose from, and apparently NONE of them can get their **** together yet.
Im going to say for the sake of arguement if there is such a close hp output between these two drastically different style heads than run l92's on an auto and ls6's on a stick. That's the race I want to see. Same car, rpm and weight to try and keep it easy. I am one who dose not believe in dyno numbers. I belive in who wins.
If any body wants to go crazy. Do them both on sticks and both on auto's and see which gets the better average numbers.
If any body wants to go crazy. Do them both on sticks and both on auto's and see which gets the better average numbers.
And I'm always too late on an LS2 TB.
I drove a 2010 Camaro SS the other day, first time I've been in one. Damn that thing has way more torque than my 2000 LS1. I don't know if the added torque is from the larger cubic inches or the heads or both. I was quite surprised.
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From: Mississippi
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Joined: Sep 2014
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From: Mississippi
A car that spends 90 percent of its time on the street I'd do a cathedral head....... I have my reasons....
A car that spends most of its time on the strip I'd do a Rectangle but Only if I got a great bore to support the big valves.....
A car that spends most of its time on the strip I'd do a Rectangle but Only if I got a great bore to support the big valves.....
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Please clarify I would hate to put this together and be shamed by someone with 243/799's on a 370ci
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So you are saying I should not have went with Rectangle Port heads on my build and went with a 243/799 heads? I see this stuff all the time and makes me wonder if I did the wrong thing. I have cam spec'd for CNC LS3's with big spray so it prob wouldn't work for crap on Cathedral Head
Please clarify I would hate to put this together and be shamed by someone with 243/799's on a 370ci
Please clarify I would hate to put this together and be shamed by someone with 243/799's on a 370ci
From what I have seen PROVEN...... A Rectangle head sucks with a fast/LS3 type intake. Those heads like to breath up high in the rpm band and the designs of them intakes just disagree. Like 4500 rpm they just now really start pumping the air or just seems to really take off around there. If you notice all the guys that's really running fast at the track with LS3/L92 heads all is running a hi rise type intake and have cut the cowl or have plenty of hood clearance. Also those cars are running way over 7k rpm on the top end also which I personally don't like cause its harder on lifters etc.. plus I notice those combos love a lot of stall. Those guys keep they cam specs under the rug too cause they know the heads/combos or a hit or miss and have to be Cammed perfectly.
The FAST intake seems to run out of breath just under 7k rpm but let's be honest how many REAL street cars go to 7K RPM? Not many!!
These type of intakes seem to do BEST with cathedral heads! Cathedral heads are easier to cam and have a very flat torque curve which is what you want on a street car. Torque is what moves you not horsepower and that's where cathedral heads tend to shine most!! They cathedral heads build great velocity and don't need that large of a split on the cam like rectangle heads need. The reason rectangle heads need that split I'd to try to balance out the poor intake/exhaust ratio those heads tend to have. If you wanted to spin the cathedral headed motor north of 7 grand I really recommend running a ported FAST by Mamo.
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I'm running LS3 heads/intake on a 370 ci LQ block right now.......
My cam is a 229/244 and wish I went smaller to be honest. Just wished the power would kick in sooner. Your motor will run strong but I'm go day it again. THE CAM SPECS IS CRITICAL!! Very very critical.
My cam is a 229/244 and wish I went smaller to be honest. Just wished the power would kick in sooner. Your motor will run strong but I'm go day it again. THE CAM SPECS IS CRITICAL!! Very very critical.
Thanks everyone from causing me heartache after I got her together, I think I may just say heck with it and put AI 317's and a turbo on it and be done
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That's weird because I drove a 2013 Camaro ss 6 speed with some special package and 3.91 gears and I was disappointed in the power. I had a 2008 vette with a 6 speed, 3:42 gears and that thing felt way faster than the Camaro. I know its lighter but the Camaro felt doggy down low.
Well I would not have sold it. I running LS3 heads on my 370 , to me 4.030 is the dividing line anything smaller I would go cathedral. With LS3 the bigger the better 4.070 to 4.10 bore would be ideal , you don't want to crowd the exhaust side it needs all the help it can get. Cam you dont need big duration just keep a good split between .
I've seen a few reasons on here as to why that gut feel of liking cathedrals makes sense. The one that stands out to me is the rectangles came on engines with VVT, but in the third gen boards, we aren't usually running VVT. So here is a question - purely educational..
What makes certain cams work well with rectangle port heads? Is it earlier IVC's that help, earlier EVO's, certain overlap bias?
What makes certain cams work well with rectangle port heads? Is it earlier IVC's that help, earlier EVO's, certain overlap bias?
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From: Mississippi
I've seen a few reasons on here as to why that gut feel of liking cathedrals makes sense. The one that stands out to me is the rectangles came on engines with VVT, but in the third gen boards, we aren't usually running VVT. So here is a question - purely educational..
What makes certain cams work well with rectangle port heads? Is it earlier IVC's that help, earlier EVO's, certain overlap bias?
What makes certain cams work well with rectangle port heads? Is it earlier IVC's that help, earlier EVO's, certain overlap bias?
Great question!! I tell you what I think...... I honestly think no one knows. I may be wrong but if I am why is the builds using these heads a hit or miss and most guys running these cams are very secretive about their specs.......
Prob bc the guys that know how to cam a square port engine are few and far between, and like to keep their cards to their chest...?