Square Port heads vs. Cathedral Port heads
10-10-2010, 12:15 AM
#81
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You missed the point or used selective reading.... We are discusiing what takes place during a test.... and during a test whether it be at the track or dyno, most do not stop and port heads, change valves,angles at the track or during the dyno session... So for testing purposes the heads are fixed......
Read the highlighted area below.... I said during dyno or track testing..
Read the highlighted area below.... I said during dyno or track testing..
10-10-2010, 12:33 AM
#82
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So basically a head is created, it flows great, but it create a lil less torque, than a cam is selected, a good intake, and then other stuff such as VVT is added and it all masks that up? What does it matter if you can't test em, results are results, L92's might make more peak HP but they make less torque than a cathedral PERIOD
Last edited by bozzhawg; 10-10-2010 at 01:15 AM.
10-10-2010, 05:00 PM
#84
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Gents
The thread is very nice and has good facts...
It is very intresting to see feedback from the proff.
I wish this thread will continoue with more explaination...
The thread is very nice and has good facts...
It is very intresting to see feedback from the proff.
I wish this thread will continoue with more explaination...
10-10-2010, 10:06 PM
#85
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I jumped on the L92 band wagon and 3 cams later it's finally coming around. That being said why is their 580-600 wheel trickflow headed cars and only one 577 wheel l92 headed car? Why is their 535 wheel 235 trickflow Ls3's and only 500-520 wheel cnc'd Ls3 headed Ls3's? Just asking please don't bring up Ls7 stuff.
I just want to post some of my experiences with l92's and cathedral port heads.
here are some of the combinations we have done.
6.0 gto wcch l92's ls3 intake 505 rwhp
6.2 vette wcch l92's ls3 intake 521 rwhp
416 gto va speed l92's ls3 intake 540 rwhp
427 vette wcch l92's fast 102 577 rwhp 656 fwhp
427 fbody wcch l92's fast 102 665 fwhp-not in car yet.
cathedral similar to above
6.0 gto tfs 225''s fast 90 525rwhp
416 gto tfs 235's fast 90 (a4) 505rwhp
427 gto tfs 235's fast 90 550 rwhp(a4) 654 fwhp
with that being said-the l92's have no place on a small displacement engine,especially a 4.0 bore engine. While they make pretty decent power on the smaller engine the low end sucks. The 6.2 vette actually drove really great and had excellent throttle response.
the bigger engines-416, 427, the l92's def shined on them. While we made similar power with the tfs heads, it should also be noted the cathedral's required a much larger cam. The larger cam actually sacrificed more tq down low than the larger port smaller cam did.
What it comes down to is this,every engine needs a different head. What works well on a 6.0 shouldn't and doesn't work nearly as good on a 427 and vise versa. Any good engine builder knows this. On smaller engines i will always defer to a smaller head-this is where catherdral ports shine,these engine need to make tq,always remeber you can't have hp without tq. On a larger engine 400+ with a 4.065 and larger bore, i will run a square port. On the larger engines i can sacrifice some low end for top end as usually there is too much for street cars anyway.
There are also other variables to consider too. How heavy is the car,what's it used for etc. The will determine which is better for the application. If it's something that's going to get sprayed, you can get away with a bigger port. Turbo,smaller port.
You simply cannot put a blanket statement that one type of head is better than another. Every head has it's place that it shines over the others. Otherwise everybody would only make one head at one port volume. Just remember, everything is a compromise. You have to sacrifice one thing for another when building engines.
here are some of the combinations we have done.
6.0 gto wcch l92's ls3 intake 505 rwhp
6.2 vette wcch l92's ls3 intake 521 rwhp
416 gto va speed l92's ls3 intake 540 rwhp
427 vette wcch l92's fast 102 577 rwhp 656 fwhp
427 fbody wcch l92's fast 102 665 fwhp-not in car yet.
cathedral similar to above
6.0 gto tfs 225''s fast 90 525rwhp
416 gto tfs 235's fast 90 (a4) 505rwhp
427 gto tfs 235's fast 90 550 rwhp(a4) 654 fwhp
with that being said-the l92's have no place on a small displacement engine,especially a 4.0 bore engine. While they make pretty decent power on the smaller engine the low end sucks. The 6.2 vette actually drove really great and had excellent throttle response.
the bigger engines-416, 427, the l92's def shined on them. While we made similar power with the tfs heads, it should also be noted the cathedral's required a much larger cam. The larger cam actually sacrificed more tq down low than the larger port smaller cam did.
What it comes down to is this,every engine needs a different head. What works well on a 6.0 shouldn't and doesn't work nearly as good on a 427 and vise versa. Any good engine builder knows this. On smaller engines i will always defer to a smaller head-this is where catherdral ports shine,these engine need to make tq,always remeber you can't have hp without tq. On a larger engine 400+ with a 4.065 and larger bore, i will run a square port. On the larger engines i can sacrifice some low end for top end as usually there is too much for street cars anyway.
There are also other variables to consider too. How heavy is the car,what's it used for etc. The will determine which is better for the application. If it's something that's going to get sprayed, you can get away with a bigger port. Turbo,smaller port.
You simply cannot put a blanket statement that one type of head is better than another. Every head has it's place that it shines over the others. Otherwise everybody would only make one head at one port volume. Just remember, everything is a compromise. You have to sacrifice one thing for another when building engines.
OK, I was waiting for the physics but got something else......
Lets go to school for a sec....... I mixed the variables up earlier my bad
sue me, I have more time than money.... but any how...
Lets kill the it flows more here or there function for a sec, lets take away the port design, etc.... And what do we have? basically an air pump... A head is a controlled variable in scientific terms of testing.... When testing heads for performance, the characteristics of the heads are fixed in most test.. When dynoing or track, flow bench etc, most do not alter by changing the port design,porting, valves, etc they are as is in most testing.... Now the camshaft and its timing events, here is your independent variable or variable that can be manipulated and changed to impact outcome of data.... The camshaft and its timing events dictate when the air starts and stops, and also how much air is allowed in. Example take the L92 or Cathedral ports and have the wrong or not optimal timing events and yeilds will be less desirable or not be the most effcient.. But people believe that just because they have a certain head, its going to magically shine.....You ve been pounded with marketing of flow and velocity but that is only if camshaft timimng is selected properly.....
So in the level of importance, and we will use your logic or analogy of breathing, whats more important how wide or closed your mouth is or your heart's ability to pump and send a signal and blood to your lungs to have the capablitlity to contract and retract and pump air and O2 into your blood stream? The brain's only functions as long as blood is flowing through it to allow synthesization of the brain functions ie the ability to cognitively know or rationalize when to open your mouth or close..... or nose.....another example,ability to hold your breath, I have said in the past that the camshaft is the brain of the engine but for this analogy we will say it as the heart.... stop the heart, no blood flow to the brain, no bloodflow to other oragans right?.....
Mouth/nose=intake
lungs=heads
heart=camshaft
azz= exhaust.......just kidding here....
take away the heart, no lungs, no air,
take away the camshaft no head airflow into the cylinder period...
Again, The camshaft dictates when the air enters the cylinder and stops entering.... It also plays a major role in how much air enters the cylinder as well...... The camshaft tells the heads what to do, the heads do not tell the camshaft what to do......
You ever noticed why with most cathedral port heads you have to run larger duration cams to produce big power or equvical power of the L92's(with shorter intake durations)? All you are doing is holding and closing the valve later which in turns allows more time for the fresh air volume to fill the cylinder... It needs more time to fill the cylinder do to the smaller port....oops did I say that.....lol..... But I thought velocity was the king rule.....
Your comment on torque has more to do with:
a cylinder is only going to fill with so much fresh air per camshaft timing.... There is a certain point where you get deminishing returns on air flow truth be told.... The smaller port does not garuntee that you will make more torque, there is more to it....
On 6.0's
Most L92 combos 220-230 intake durations put down 450-490rwhp.
Now try that with most cathedral port heads, we know they need more duration right? 230-240's+.... I wonder why? I thought the higher velocity would make them make even more power right? Sounds like that the smaller port needs more time to fill the cylinder due to the port size.... Think about this, simple test, blow into a standard 16oz straw and blow into route 44 straw from sonic, and if we placed a sealable cap on top...which would fill the cup full of air faster and take less time if velocity was the same or +/- a few...? Does the motor or engine cycle know or even care about the port design really? No, it only cares about how much air or volume of air has entered the cylinder to compress,ignite,powerstroke, exhaust(excuvate the gases out)....
So when youi see a guy with a 6.0/L92 224/230 .581/.591 10.9-11.1 compression putting down 475rwhp and you see a guy with a cathedral port 225(TFS,AFR) putting down 490-500+ with a 236/242 .595/595 or 236+ intake durations, plus generally 11:3-11:5 compression, you do the math..... 12 more degrees of intake duration right? The valve is open longer right? So in a since the cylinder is requiring more air to go through the 4 stages of the engine cycle to produce the yeilds...... Which shifts the torque curve outward, which shifts the point that maxium cylinder pressure is reached and shifts out the point where the cam shaft is no longer able to excuvate the exhaust gases and the intake charge and exhaust gases mix aka peak power.....
So there is more to the story than just headflow or velocity, we have not even discussed intake,exhaust system,valvetrain,drivetrain, tunning, etc....
Bozz
To Badd SS: I agree bro, sheep, always follow the paper trail......
Lets go to school for a sec....... I mixed the variables up earlier my bad
sue me, I have more time than money.... but any how...
Lets kill the it flows more here or there function for a sec, lets take away the port design, etc.... And what do we have? basically an air pump... A head is a controlled variable in scientific terms of testing.... When testing heads for performance, the characteristics of the heads are fixed in most test.. When dynoing or track, flow bench etc, most do not alter by changing the port design,porting, valves, etc they are as is in most testing.... Now the camshaft and its timing events, here is your independent variable or variable that can be manipulated and changed to impact outcome of data.... The camshaft and its timing events dictate when the air starts and stops, and also how much air is allowed in. Example take the L92 or Cathedral ports and have the wrong or not optimal timing events and yeilds will be less desirable or not be the most effcient.. But people believe that just because they have a certain head, its going to magically shine.....You ve been pounded with marketing of flow and velocity but that is only if camshaft timimng is selected properly.....
So in the level of importance, and we will use your logic or analogy of breathing, whats more important how wide or closed your mouth is or your heart's ability to pump and send a signal and blood to your lungs to have the capablitlity to contract and retract and pump air and O2 into your blood stream? The brain's only functions as long as blood is flowing through it to allow synthesization of the brain functions ie the ability to cognitively know or rationalize when to open your mouth or close..... or nose.....another example,ability to hold your breath, I have said in the past that the camshaft is the brain of the engine but for this analogy we will say it as the heart.... stop the heart, no blood flow to the brain, no bloodflow to other oragans right?.....
Mouth/nose=intake
lungs=heads
heart=camshaft
azz= exhaust.......just kidding here....
take away the heart, no lungs, no air,
take away the camshaft no head airflow into the cylinder period...
Again, The camshaft dictates when the air enters the cylinder and stops entering.... It also plays a major role in how much air enters the cylinder as well...... The camshaft tells the heads what to do, the heads do not tell the camshaft what to do......
You ever noticed why with most cathedral port heads you have to run larger duration cams to produce big power or equvical power of the L92's(with shorter intake durations)? All you are doing is holding and closing the valve later which in turns allows more time for the fresh air volume to fill the cylinder... It needs more time to fill the cylinder do to the smaller port....oops did I say that.....lol..... But I thought velocity was the king rule.....
Your comment on torque has more to do with:
a cylinder is only going to fill with so much fresh air per camshaft timing.... There is a certain point where you get deminishing returns on air flow truth be told.... The smaller port does not garuntee that you will make more torque, there is more to it....
On 6.0's
Most L92 combos 220-230 intake durations put down 450-490rwhp.
Now try that with most cathedral port heads, we know they need more duration right? 230-240's+.... I wonder why? I thought the higher velocity would make them make even more power right? Sounds like that the smaller port needs more time to fill the cylinder due to the port size.... Think about this, simple test, blow into a standard 16oz straw and blow into route 44 straw from sonic, and if we placed a sealable cap on top...which would fill the cup full of air faster and take less time if velocity was the same or +/- a few...? Does the motor or engine cycle know or even care about the port design really? No, it only cares about how much air or volume of air has entered the cylinder to compress,ignite,powerstroke, exhaust(excuvate the gases out)....
So when youi see a guy with a 6.0/L92 224/230 .581/.591 10.9-11.1 compression putting down 475rwhp and you see a guy with a cathedral port 225(TFS,AFR) putting down 490-500+ with a 236/242 .595/595 or 236+ intake durations, plus generally 11:3-11:5 compression, you do the math..... 12 more degrees of intake duration right? The valve is open longer right? So in a since the cylinder is requiring more air to go through the 4 stages of the engine cycle to produce the yeilds...... Which shifts the torque curve outward, which shifts the point that maxium cylinder pressure is reached and shifts out the point where the cam shaft is no longer able to excuvate the exhaust gases and the intake charge and exhaust gases mix aka peak power.....
So there is more to the story than just headflow or velocity, we have not even discussed intake,exhaust system,valvetrain,drivetrain, tunning, etc....
Bozz
To Badd SS: I agree bro, sheep, always follow the paper trail......
So assuming I have a 454 CID LSx Engine, WHICH HEAD WOULD BE BEST FOR A STREET APPLICATION?
Would it be best with a Cathedral port head like a TFS 245 (for more power across the powerband) and topped off with a Ported FAST 102 setup OR A set of L92 Heads that will shine up top b/c of it's larger Valves, and topped off with a ported Single Plane Intake?
B/c from what I have always been told (may be sold to marketing)
But a smaller port = more power under the curve and thus making more tq. and hp throughout with an exception of Peak power... therefore being more optimal for a street setup!This is just a little something I am concerned with since we have all been talking stock CID engines. I'm more concerned with Big CID Engines since thats the route I will be going.
But When using a bigger CID Engine, I can't help but think with the L92's it would fill the cylinder faster than a Cathedral Port head and therefore make power sooner and ultimately make more power throughout. (and use a smaller duration cam and less lift as well to make great power) I keep confusing myself b/c I try to look at it from both points of views...
I guess I'm also looking at what would be more efficent for a "street" Big CID Engine (and given the cam choices would have to be spec'd differently), what would be the more desirable/have more longevity over the other... I would asume the TFS 245 heads would need to rev higher thus taking away longevity of an engine as opposed to L92 heads! Is this correct?
I say that b/c the TFS heads will need a larger cam to allow them to properly fill the cylinder as opposed to the L92's with a larger intake valve that would fill the cylinder sooner and thus not need to open as far as the smaller valve heads!
Please shed some light on this... I am trying to learn a little something here.
10-10-2010, 11:37 PM
#86
TECH Enthusiast
*These are all very good points....And make me wanna ask a question!
So assuming I have a 454 CID LSx Engine, WHICH HEAD WOULD BE BEST FOR A STREET APPLICATION?
Would it be best with a Cathedral port head like a TFS 245 (for more power across the powerband) and topped off with a Ported FAST 102 setup OR A set of L92 Heads that will shine up top b/c of it's larger Valves, and topped off with a ported Single Plane Intake?
B/c from what I have always been told (may be sold to marketing) But a smaller port = more power under the curve and thus making more tq. and hp throughout with an exception of Peak power... therefore being more optimal for a street setup!
This is just a little something I am concerned with since we have all been talking stock CID engines. I'm more concerned with Big CID Engines since thats the route I will be going.
But When using a bigger CID Engine, I can't help but think with the L92's it would fill the cylinder faster than a Cathedral Port head and therefore make power sooner and ultimately make more power throughout. (and use a smaller duration cam and less lift as well to make great power) I keep confusing myself b/c I try to look at it from both points of views...
I guess I'm also looking at what would be more efficent for a "street" Big CID Engine (and given the cam choices would have to be spec'd differently), what would be the more desirable/have more longevity over the other... I would asume the TFS 245 heads would need to rev higher thus taking away longevity of an engine as opposed to L92 heads! Is this correct?
I say that b/c the TFS heads will need a larger cam to allow them to properly fill the cylinder as opposed to the L92's with a larger intake valve that would fill the cylinder sooner and thus not need to open as far as the smaller valve heads!
Please shed some light on this... I am trying to learn a little something here.
So assuming I have a 454 CID LSx Engine, WHICH HEAD WOULD BE BEST FOR A STREET APPLICATION?
Would it be best with a Cathedral port head like a TFS 245 (for more power across the powerband) and topped off with a Ported FAST 102 setup OR A set of L92 Heads that will shine up top b/c of it's larger Valves, and topped off with a ported Single Plane Intake?
B/c from what I have always been told (may be sold to marketing)
But a smaller port = more power under the curve and thus making more tq. and hp throughout with an exception of Peak power... therefore being more optimal for a street setup!This is just a little something I am concerned with since we have all been talking stock CID engines. I'm more concerned with Big CID Engines since thats the route I will be going.
But When using a bigger CID Engine, I can't help but think with the L92's it would fill the cylinder faster than a Cathedral Port head and therefore make power sooner and ultimately make more power throughout. (and use a smaller duration cam and less lift as well to make great power) I keep confusing myself b/c I try to look at it from both points of views...
I guess I'm also looking at what would be more efficent for a "street" Big CID Engine (and given the cam choices would have to be spec'd differently), what would be the more desirable/have more longevity over the other... I would asume the TFS 245 heads would need to rev higher thus taking away longevity of an engine as opposed to L92 heads! Is this correct?
I say that b/c the TFS heads will need a larger cam to allow them to properly fill the cylinder as opposed to the L92's with a larger intake valve that would fill the cylinder sooner and thus not need to open as far as the smaller valve heads!
Please shed some light on this... I am trying to learn a little something here.
10-11-2010, 09:31 AM
#88
TECH Enthusiast
Not reccomended
depends, you'll have to shop around, they start around $900+ each.... I have not really been keeping track of their prices lately...... Hell the LS3 heads with the hollow stem intake valves and stock springs are $336-$375 now on sale.... cain't beat that.....
depends, you'll have to shop around, they start around $900+ each.... I have not really been keeping track of their prices lately...... Hell the LS3 heads with the hollow stem intake valves and stock springs are $336-$375 now on sale.... cain't beat that.....
Last edited by bozzhawg; 10-11-2010 at 09:43 AM.
10-11-2010, 11:50 AM
#89
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Bozz, Is there any specific reason behind using the LS7 Heads over the TFS 245 or LS3 heads?
Just curious as to why they would be better. Port size, flow, etc. ??
More power under the curve, or ??
Just curious as to why they would be better. Port size, flow, etc. ??
More power under the curve, or ??
10-11-2010, 03:21 PM
#90
TECH Enthusiast
I am going to take a different approach on this one....
Do your research and look at the designs, line them up with your goals and honest intent and your answer will come.... And don't pay anybody for their specualtion or guess unless or untill you have a full understanding why they are making the suggestions and why you are making your choice....
Lets clear some things, I am by no means saying that the cathedral port or aftermarket versions are an inferrior design.... I was just stating some facts and observations that conflict with the mass marketing that has plagued the performance masses and mostly blog boards.... There is a climate or atomosphere that has been around that if you don't have brand X or Z then your performance is lacking or inferrior... This only shows that the marketing ploys are working and they are doing a good job of it......
The information I stated is not backed by any financial motive or entity. And with any marketing, always follow the paper trail...... One thing I have learned is people are usually lead by either facts,what they are exposed to, or their pocket book......
If you noticed in the last conversation I had with the other fellow, if I came out and said well..... go with brand X then someone will pull out a dyno... saying its not true or somebody else got this with that or brand Z says this...... Or another example are guys with dick dong cams that they drive as daily drivers.... Then the question of driveability comes up... What is driviability? Each person will have their own level of what is considered to be driveable....
So in the last conversation did I change his mind? No, he still believes that the brand Z is better than X and I can talk in scienctifc terms, physic equations, post 1,000 dynos, 1,000, ETs and MPH.... but how many will admit it on a blog board that there maybe another option?
So, you see....? I m tired..... PM me ......
Bozz
10-12-2010, 12:28 AM
#92
I like the guy who posted similar combinations of l92 vs tfs 245. I don't know what the tfs heads cost but I'm guessing they are nowhere close to being as cheap as the l92s.
This document shed some light on the l92s and boost, so much so that my next build will use the "torqueless" l92 heads
This document shed some light on the l92s and boost, so much so that my next build will use the "torqueless" l92 heads
10-12-2010, 01:50 PM
#95
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So in the last conversation did I change his mind? No, he still believes that the brand Z is better than X and I can talk in scienctifc terms, physic equations, post 1,000 dynos, 1,000, ETs and MPH.... but how many will admit it on a blog board that there maybe another option?
So, you see....? I m tired..... PM me ......
Bozz
So, you see....? I m tired..... PM me ......
Bozz
10-12-2010, 06:01 PM
#96
CLEARLY the L92 heads will not run. I mean, they really suck, I have only been able to trap 120 mph in a 9.6:1,cam and bolt on's 6.0L with them in my 3424lb camaro. they definately dont like 6.0L's either. I better go get some expensive cathedral's.
10-12-2010, 07:42 PM
#97
An issue that gets lost in this controversy over the two types of heads is the intakes that most of us have to use with the hood clearance issues. The intakes limit flow on a lot of combinations especially in the rpm department. This has the effect of making the smaller port heads more efficient cause it is a better match. Much of the fine tuning of the ls cathedral heads is with the intake limitations in mind. I believe the square port heads would work better with single planes than the cathdrals.
10-12-2010, 08:04 PM
#98
Why expensive cathedrals? A 120mph trap at 3424 lbs is what, <450rwhp? If that's the benchmark being pursued just use inexpensive 243s.
10-12-2010, 08:18 PM
#100
An issue that gets lost in this controversy over the two types of heads is the intakes that most of us have to use with the hood clearance issues. The intakes limit flow on a lot of combinations especially in the rpm department. This has the effect of making the smaller port heads more efficient cause it is a better match. Much of the fine tuning of the ls cathedral heads is with the intake limitations in mind. I believe the square port heads would work better with single planes than the cathdrals.
Yup! Don't work.
Last edited by WKMCD; 10-12-2010 at 08:28 PM.