Square Port heads vs. Cathedral Port heads
06-29-2020, 12:57 PM
#181
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Good info.
I heard the LS3 head was destined to be in the Z06 and it didn't meet GM's goals so they scrapped it and the LS7 was the finished product.
Because they spent a lot of $ on R&D, they recycled this head for the LS3 and didn't want their efforts to go waste.
Apparently, the LS3 head was designed in the late 1990's.
(I will try and find the article and post the link here)
You are right about the cathedrals.
The design compromises are obvious with the narrower port.
The rule of thumb is to lower intake duration by about 5 degrees when using square port due to the reasons mentioned.
Actually if they put the 243 head on the trucks they would drive a lot better in the lower RPM ranges.
Then you VVT etc so that changes the equation somewhat too.
I heard the LS3 head was destined to be in the Z06 and it didn't meet GM's goals so they scrapped it and the LS7 was the finished product.
Because they spent a lot of $ on R&D, they recycled this head for the LS3 and didn't want their efforts to go waste.
Apparently, the LS3 head was designed in the late 1990's.
(I will try and find the article and post the link here)
You are right about the cathedrals.
The design compromises are obvious with the narrower port.
The rule of thumb is to lower intake duration by about 5 degrees when using square port due to the reasons mentioned.
Actually if they put the 243 head on the trucks they would drive a lot better in the lower RPM ranges.
Then you VVT etc so that changes the equation somewhat too.
A recent interview with Chris Meagher, GM's assistant chief engineer for small-block truck V-8 engines, turned up some fascinating info on the new L92 V-8. This 6.2-liter, 376-inch engine will debut in early 2006 in the Cadillac Escalade and Chevy Tahoe, and will be rated at 400 hp and 415 pounds of torque. The aluminum L92 possesses forged rods, variable valve timing (a first for mass-produced, OHV V-8s), crankcase windows for improved bay-to-bay breathing, and a powerful, 32-bit E38 ECM.
But even more intriguing is that this powerful new Gen IV's cylinder heads got a heaping portion of technology transfer from the 7.0L LS7 heads.
But even more intriguing is that this powerful new Gen IV's cylinder heads got a heaping portion of technology transfer from the 7.0L LS7 heads.
06-29-2020, 01:16 PM
#182
TECH Veteran
A couple facts to add...
The Cookbook thread told and showed people alot.
Its pretty cool seeing the throw away 241 heads go just as fast or faster as some heads that's north 3 thousand dollars.
The thread also show me that the out the box LS3 head or just as good as the aftermarket LS3 heads.
Over 40 combos in that thread and all was different and each car/combo had a flaw which made it more interesting.
Carry on
The Cookbook thread told and showed people alot.
Its pretty cool seeing the throw away 241 heads go just as fast or faster as some heads that's north 3 thousand dollars.
The thread also show me that the out the box LS3 head or just as good as the aftermarket LS3 heads.
Over 40 combos in that thread and all was different and each car/combo had a flaw which made it more interesting.
Carry on
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Che70velle (06-29-2020)
06-29-2020, 01:33 PM
#183
LS7 heads were used to develop the LS3 heads, not the other way around. See below:
http://www.superchevy.com/how-to/eng...en-4-ls7-heads
http://www.superchevy.com/how-to/eng...en-4-ls7-heads
Got me thinking.
06-29-2020, 05:38 PM
#184
TECH Resident
i dont understand why people worry about torque on large cubic inch engines, maybe thats because i cant drive around with 18inch super stick tyres.
All i know is i can be at 1500rpm and if i wanna go i just push the pedal and all hell breaks lose and my super sticky 12inch tyres dont get traction till about 70mph.
Mayb i should get those 18inch tyres, hook up a 30ft caravan , and see how much torque i have.
before the ls7 head i had the btr 239/254, ported oem ls3 heads with a 2.180 intake valve lsxr 102 intake... 573rwhp/540ftlb with 3.23 rear gear
All i know is i can be at 1500rpm and if i wanna go i just push the pedal and all hell breaks lose and my super sticky 12inch tyres dont get traction till about 70mph.
Mayb i should get those 18inch tyres, hook up a 30ft caravan , and see how much torque i have.
before the ls7 head i had the btr 239/254, ported oem ls3 heads with a 2.180 intake valve lsxr 102 intake... 573rwhp/540ftlb with 3.23 rear gear
06-29-2020, 06:14 PM
#185
TECH Veteran
i dont understand why people worry about torque on large cubic inch engines, maybe thats because i cant drive around with 18inch super stick tyres.
All i know is i can be at 1500rpm and if i wanna go i just push the pedal and all hell breaks lose and my super sticky 12inch tyres dont get traction till about 70mph.
Mayb i should get those 18inch tyres, hook up a 30ft caravan , and see how much torque i have.
before the ls7 head i had the btr 239/254, ported oem ls3 heads with a 2.180 intake valve lsxr 102 intake... 573rwhp/540ftlb with 3.23 rear gear
All i know is i can be at 1500rpm and if i wanna go i just push the pedal and all hell breaks lose and my super sticky 12inch tyres dont get traction till about 70mph.
Mayb i should get those 18inch tyres, hook up a 30ft caravan , and see how much torque i have.
before the ls7 head i had the btr 239/254, ported oem ls3 heads with a 2.180 intake valve lsxr 102 intake... 573rwhp/540ftlb with 3.23 rear gear
06-29-2020, 07:35 PM
#187
TECH Veteran
06-29-2020, 08:22 PM
#189
TECH Veteran
06-29-2020, 08:24 PM
#190
TECH Resident
I have as much torque as i need so dropping a few ftlb in the midrange in exchange for more hp is a no brainer. rectangle for me all the way. I havnt seen any comparisons between them on a similar engine to mine, touching 665rwhp/610ftlb and thats running a really dodgy specced cam
If i was using stock bore id seriously be tossing up between the 2
06-29-2020, 08:39 PM
#191
TECH Veteran
I understand where your coming from. my comments are about a street driven large cube engine comparison about cathedral v rectangle port heads.
I have as much torque as i need so dropping a few ftlb in the midrange in exchange for more hp is a no brainer. rectangle for me all the way. I havnt seen any comparisons between them on a similar engine to mine, touching 665rwhp/610ftlb and thats running a really dodgy specced cam
If i was using stock bore id seriously be tossing up between the 2
I have as much torque as i need so dropping a few ftlb in the midrange in exchange for more hp is a no brainer. rectangle for me all the way. I havnt seen any comparisons between them on a similar engine to mine, touching 665rwhp/610ftlb and thats running a really dodgy specced cam
If i was using stock bore id seriously be tossing up between the 2
Want to start a real cool friendly argument?
Which 440ci setup you rather have?
4.0 stroke with 4.185 bore
VS
4.125 stoke and 4.125 bore
Wonder which 440ci motor would be a bad MF ?
06-29-2020, 08:43 PM
#192
TECH Resident
Understanding.... but rule of thumb is that a motor with a larger stroke will generate more torque.
Want to start a real cool friendly argument?
Which 440ci setup you rather have?
4.0 stroke with 4.185 bore
VS
4.125 stoke and 4.125 bore
Wonder which 440ci motor would be a bad MF ?
Want to start a real cool friendly argument?
Which 440ci setup you rather have?
4.0 stroke with 4.185 bore
VS
4.125 stoke and 4.125 bore
Wonder which 440ci motor would be a bad MF ?
06-29-2020, 09:47 PM
#193
11 Second Club
iTrader: (3)
No replacement for displacement!
LSX block staying with 4.00 stroke and 4.125 bore can still take NOS and/or handle large amounts of boost. Once you exceed this you can sacrifice longevity when using power adders and its really not recommended. An LSX 454 would be the WTG in an NA only build and the standard deck can go to 472 but those types of builds are best left to the pro's and again your going to give up longevity.
Maybe I should have went a different direction and built a BBC for my 4th Gen. MSO Dennis Bailey's 4th Gen Camaro "Silverback Gorilla" is no joke!
LSX block staying with 4.00 stroke and 4.125 bore can still take NOS and/or handle large amounts of boost. Once you exceed this you can sacrifice longevity when using power adders and its really not recommended. An LSX 454 would be the WTG in an NA only build and the standard deck can go to 472 but those types of builds are best left to the pro's and again your going to give up longevity.
Maybe I should have went a different direction and built a BBC for my 4th Gen. MSO Dennis Bailey's 4th Gen Camaro "Silverback Gorilla" is no joke!
06-29-2020, 11:39 PM
#194
I thought about going to a big block. But then you see cars like this and think otherwise..
https://www.yellowbullet.com/threads...o-fyi.2627598/
https://www.yellowbullet.com/threads...o-fyi.2627598/
06-30-2020, 02:56 AM
#195
I thought about going to a big block. But then you see cars like this and think otherwise..
https://www.yellowbullet.com/threads...o-fyi.2627598/
https://www.yellowbullet.com/threads...o-fyi.2627598/
06-30-2020, 03:13 AM
#196
Realistically, what is even the point of building a crazy *** motor if your not going to do what is needed to get it to the ground?
On the street. 28-15-10.5 Hoosier Quick Time Pro's. When we had the QA1's it would pull the front tires a foot off the ground for about 40 feet on the street, but that's with a good chassis and suspension too.
On the street. 28-15-10.5 Hoosier Quick Time Pro's. When we had the QA1's it would pull the front tires a foot off the ground for about 40 feet on the street, but that's with a good chassis and suspension too.
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Darth_V8r (06-30-2020)
06-30-2020, 04:01 AM
#197
Realistically, what is even the point of building a crazy *** motor if your not going to do what is needed to get it to the ground?
On the street. 28-15-10.5 Hoosier Quick Time Pro's. When we had the QA1's it would pull the front tires a foot off the ground for about 40 feet on the street, but that's with a good chassis and suspension too.
On the street. 28-15-10.5 Hoosier Quick Time Pro's. When we had the QA1's it would pull the front tires a foot off the ground for about 40 feet on the street, but that's with a good chassis and suspension too.
As for that fox body, who knows. There are a couple of cam-only n/a 6.0 litre foxes well into the 9 seconds 1/4 also. Don't forget that BTR car is 2800 race weight, in my experience the LS's really begin losing it the lighter the car gets. Texas Speed also ran 8.9 in a n/a sbe ls3, max effort.
06-30-2020, 04:18 AM
#198
Also i think for every person who puts in the max effort and also has the correct knowledge to get the most impressive ET from their car at the drag strip, there are 100 or more others who can't do the same. That doesn't mean the one-off fast cars are BS'ing or have hidden NOS. The difference in camshaft alone can make one car ET 0.5 second quicker than another, let alone other variables. That fox body is 400+ ci and high CR race gas, with big AFR heads and 25x-27x camshaft . I can see it possible in 2800 race weight if everything is done right and they spent hours on the dyno or track trying a heap of different combinations, camshaft grinds etc.. like texas speed has done for example to get those sbe records.
06-30-2020, 04:27 AM
#199
There is more than one way to skin a cat.
I'm not getting my AFR heads for drag racing.
It's for driveability but you can certainly do drag racing or make the combination more extreme for different purposes.
I still think heavy *** cars like mine at over 4000lb benefit from the extra kick of the cathedral for daily use.
I'm not getting my AFR heads for drag racing.
It's for driveability but you can certainly do drag racing or make the combination more extreme for different purposes.
I still think heavy *** cars like mine at over 4000lb benefit from the extra kick of the cathedral for daily use.
06-30-2020, 04:43 AM
#200
Mr T. You are in love with the head. I don't sense a divorce any time soon.
LOL yes I am. and I don't either.
Based on what you have seen at the track would you say the Trickflows have ran faster than the AFR?
No not at all. Pretty much the same from what I have seen. Depends on the combo and weight. Not very many run the AFR head on the LS for some reason. That is why I say it is a very underrated head.
I know they are closely matched. On paper the trickflows appear to be superior with smaller valves and ports and a 13.5 degree valve angle but the real world is a different story and is something I have wanted to know. I would have been happy whichever one I had picked.
They both are very fine heads. You would have been good either way. I have always loved to do things different than others. You have to have a sense of adventure. Lol
Hell when have you seen someone adapt a CID to catheadral heads? Lol
You also have Mast's 11 degree cathedral heads as another option but there is no data which shows if they outperform the trickflows and AFR's.
On paper these Mast heads appear superior but how can we know?
The guys with the mast heads I have seen did not impress me at all. Not sure which ones they were. They were all injected and they all seemed to be having problems getting the fuel mapped out right. But there was one guy that definitely had a set of Mast 245 cathedrals with the Mast cathedral carbed Dominator intake that was very fast. We tried to get next to him but he conveniently kept away from us. It was pretty much the same car too. Was dieing to see what he had, because he was spraying too. Would have been nice to compare them. May have been the fact that he was running his mouth and said what most all say that don't want to race. I don't race for less than 500. Before he blinked his eyes we had 500 in his face. Lol Then it was the old well I would BUT.
The guys
I like the LS7 heads a lot and I would use these heads if I was building an engine that revved well over 7000rpm.
Brother, you are going to be so happy with your motor you will forget all about all that HYPE. Hell, we shift ours at 7400.
I'm going to go for a drive with Mick one day this year once he gets his engine fixed etc to see how it feels on the road.
I would race him when yours is done. Me and my friends race each other all the time. Just gives us one more thing to mess with each other about. Its all in good fun.
I have heard that the cathedral heads work a lot better with boost because of the exhaust port efficiency.
Tooley did a video on the tuning school explaining how this works and why you pick up power.
LOL yes I am. and I don't either.
Based on what you have seen at the track would you say the Trickflows have ran faster than the AFR?
No not at all. Pretty much the same from what I have seen. Depends on the combo and weight. Not very many run the AFR head on the LS for some reason. That is why I say it is a very underrated head.
I know they are closely matched. On paper the trickflows appear to be superior with smaller valves and ports and a 13.5 degree valve angle but the real world is a different story and is something I have wanted to know. I would have been happy whichever one I had picked.
They both are very fine heads. You would have been good either way. I have always loved to do things different than others. You have to have a sense of adventure. Lol
Hell when have you seen someone adapt a CID to catheadral heads? Lol
You also have Mast's 11 degree cathedral heads as another option but there is no data which shows if they outperform the trickflows and AFR's.
On paper these Mast heads appear superior but how can we know?
The guys with the mast heads I have seen did not impress me at all. Not sure which ones they were. They were all injected and they all seemed to be having problems getting the fuel mapped out right. But there was one guy that definitely had a set of Mast 245 cathedrals with the Mast cathedral carbed Dominator intake that was very fast. We tried to get next to him but he conveniently kept away from us. It was pretty much the same car too. Was dieing to see what he had, because he was spraying too. Would have been nice to compare them. May have been the fact that he was running his mouth and said what most all say that don't want to race. I don't race for less than 500. Before he blinked his eyes we had 500 in his face. Lol Then it was the old well I would BUT.
The guys
I like the LS7 heads a lot and I would use these heads if I was building an engine that revved well over 7000rpm.
Brother, you are going to be so happy with your motor you will forget all about all that HYPE. Hell, we shift ours at 7400.
I'm going to go for a drive with Mick one day this year once he gets his engine fixed etc to see how it feels on the road.
I would race him when yours is done. Me and my friends race each other all the time. Just gives us one more thing to mess with each other about. Its all in good fun.
I have heard that the cathedral heads work a lot better with boost because of the exhaust port efficiency.
Tooley did a video on the tuning school explaining how this works and why you pick up power.