Originally Posted by bozzhawg

Ok... I but explain why with the smaller your going to make more torque...?

I want to know why? You are making statement but sounds like i ts based onwhat you have been told... I want you to break it down.... because a lot of the story is not being told.... And I will tell you this, the head is not a self operating function.... really a head is a independent variable...... a camshaft would be a controlled variable.....

So explain bro....?

Originally Posted by Kaltech Tuning

Yeah, I was a little ahead of myself saying the cath. port heads are dead as you can still get them on the tiny truck motors, however gm is phasing out their cath. port stuff across the board. We know that the L92's won't fit the little in their current configuration so they'll have to make changes to accomodate that, but you do see the change coming right Pat?

I don't think the point of this article is to **** on cathedral port heads but talk about some of the positives of the square port, plus enlighten people to the poor, misinformation that's out there about the square port stuff.

The facts are that all the new stuff gm puts out makes more power and gets the same or better gas mileage as the older stuff. In terms of the truck motors the 4.8's and 6.2's both with VVT get within 1 mpg of each other while the 6.2's make 100 hp and 110 ft lbs more, 6.2's are in heavier more optioned vehicles, and the 6.2's can tow a bunch more.

Again this isn't about arguing which head is better or put one on a holy grail while crapping on the other, rather it's more about showing how technology is moving in a positive direction. We've all had great success with the cath. port stuff but the fact is now we're starting to chase technology once again.

Originally Posted by camz28arro

I'm just saying that the large runner is the cause for that midrange deficiency in the dyno link. They should have used the 245cc afr heads since they are a closer size to the size of the L92 heads. Then the cathedrials would have won but it's still against a stock casted square port.

I also did learn most I know about head design from ls1tech like you said. If there is nothing worth reading to learn I don't know what you're doing here if it's all false.

Originally Posted by jeffreycastgsx

I guess you could say that i could be making statements based on whats been writen by certain members (err, vendors), but i base my statements on whats been known for years and by my own experience. Its almost the same argument for intake manifolds, short runner vs long runner, and the interior volume can all contribute, to where peak hp and torque is gonna be made. One example would be fords 2v heads, flow like ****, and have small ports, BUT make terrific powerbands, and torque (and lots of it) everywhere. Take a look at the CFM numbers for a L92 at .400 lift and below and compare them to smaller heads, and you might notice that some smaller heads have higher flow at less lift than L92's. Big ports might put out the big numbers but they just will not have the velocity necessary to create torque at low speeds. What if you had an exhaust that was too free-flowing (just as an explanation)? You would also lose bottom end (which would be attributed to the loss of scavenging, which could be brought back by some type of crossover pipe), but thats just an example, and we all know that a properly setup exhaust will not lose much torque, just like a properly setup (and matched) head. Simply put, if you were sitting not doing much, and tried to breath which would be easier, to have your mouth wide open, or to normally breath with your nose or your mouth slightly open? Now if you were running which would be easier, with your mouth open, or with your nose? Some might say that those are SBC theories and do not apply to LS engines, but guess what, an LS engine is still an unperfect engine,and is not small magical engine that can run away from those RULES. Those theories apply to all engines, no matter the brand.



Except you can not say that they make more power and torque due to just the heads. They also have better intakes, VVT, and the 6.2's make the advertised 402hp on premium gas not regular, and im not positive on this but im pretty sure the compression went up. Gas mileage went up due to AFM/DOD, and VVT. Torque output on a L92 is just not the same as a cathedral, but neither would hp(with L92's edging out all stock casting cathedral heads). Im not saying that L92's are garbage either, i have already seen what L92's can do, just look at the 5th gen camaro, 500whp after full boltons, and a cam. Last i heard H/C/I LS1's had a hard time hitting 475whp.

Did anyone notice that the NNBS 5.3's with 243 heads made less torque than the previous NBS with the smaller port 862/706 5.3's?

Originally Posted by WKMCD

You keep ignoring facts because you couldn't make the L92 heads work. Same or better HP with a smaller cam - I'll take that all day long.

Originally Posted by camz28arro

It would be much more interesting to see a comparison of the AFR 245cc heads vs the MAST 245cc heads since they have the same size intake runners and the flow close to each other too, flow is in favor of the cathedrials though

AFR 245cc
.200...165cfm.....130
.300...238cfm.....183
.400...293cfm.....226
.500...334cfm.....247
.600...356cfm.....257

MAST 245cc
lift.....Intake..... Exhaust
0.200.. 147..........110
0.300...218..........172
0.400...274..........214
0.500...318..........234
0.600...342..........248

Originally Posted by Beaflag VonRathburg

Yeah, but what are you bolting them onto? What intake are you using? Headers, cam, etc... That's kind of what Shawn and others were saying. People like to look at heads alone. They say this head is the best it flows 350cfm at .XXX lift. What is it the best for?

Originally Posted by jeffreycastgsx

Except you can not say that they make more power and torque due to just the heads. They also have better intakes, VVT, and the 6.2's make the advertised 402hp on premium gas not regular, and im not positive on this but im pretty sure the compression went up. Gas mileage went up due to AFM/DOD, and VVT. Torque output on a L92 is just not the same as a cathedral, but neither would hp(with L92's edging out all stock casting cathedral heads). Im not saying that L92's are garbage either, i have already seen what L92's can do, just look at the 5th gen camaro, 500whp after full boltons, and a cam. Last i heard H/C/I LS1's had a hard time hitting 475whp.

Originally Posted by WKMCD

You keep ignoring facts because you couldn't make the L92 heads work. Same or better HP with a smaller cam - I'll take that all day long.

Originally Posted by Kaltech Tuning

A good test of lowend power would be to take a stock ls1 fbody put it in 6th gear at 1100 rpm and put the pedal to the floor. Next take a stock 2010 camaro and do the same thing, I guarantee you'll notice a big difference between the 2.

Originally Posted by cam

Whachoo talkin bout Willis? I think you quoted the wrong guy....

I am in the process of a build with L92 heads now I havent said anything negative about them at all Im a big fan of these heads

Originally Posted by Kaltech Tuning

A good test of lowend power would be to take a stock ls1 fbody put it in 6th gear at 1100 rpm and put the pedal to the floor. Next take a stock 2010 camaro and do the same thing, I guarantee you'll notice a big difference between the 2.

Originally Posted by bozzhawg

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......

Originally Posted by Kaltech Tuning

I think we're getting off track with all of the fuel economy stuff and some of that is my fault. I simply referenced because it's said that the square port stuff is very lazy down low and doesn't make good torque. We can simplify this and forget about the trucks for a moment to eliminate variables like vvt and dod.
The LS3 vettes make more hp and tq than the ls1 cars and get the same or better gas mileage. I could be wrong here but I believe the ls3 vette has the highest rated fuel economy of a vette to date. If not it's damn close.
Same thing with the LS3 camaro's they stomp out the ls1 camaros in performance and get the same or better mileage, and the 2010 camaro is significantly heavier than the ls1 f-body's. The LS3 camaro is only rated at 1 mpg city worse than the 6 cyl. camaro. Lowend toque can't be too bad.

A good test of lowend power would be to take a stock ls1 fbody put it in 6th gear at 1100 rpm and put the pedal to the floor. Next take a stock 2010 camaro and do the same thing, I guarantee you'll notice a big difference between the 2.

Originally Posted by jeffreycastgsx

I cant say that your wrong on most of your post but, i wont agree on somethings. For one a head can be manipulated by changing its shape, size, valve size/angle, and ultimately flow, all can dictate a powerband. It can affect peak torque, peak hp, and the shape (like as if it was posted on a dyno), of powerband. Just like a cam(which probably has a bigger effect on torque than heads), which can affect peak torque, peak hp, and the shape of a powerband. Same for an intake manifold. Displacement will also affect those things. Everyone and there grandma know that big ports exchange power down low, for power up top, small ports exchange power up top for power down low. Lets say that you had 2 engines setup exactly the same, except for heads, i GUARANTEE you that the one with a head smaller ports would create more power down low, and less up top than if it had bigger ports. Always works like this, its all with flow, of course some heads will break these rules, but those are the ones that are works of art. Marketing? Blah. L92's flow stock what AFR's and trickflow's $2500 heads flow. I can't see anyone who has a 4"+ bore using those when a much cheaper head does the same (and in other cases outperforms). Ported, they make those expensive heads look like paperweights.


Except what about gearing? Lots of factors to count and in reality we cant base the torque or mpg on JUST heads. Nowadays cars are also rated in a different way for mpg than they were 10 years. Can someone do this test, maybe someone should do some 6th gear pulls, and im serious.

Originally Posted by bozzhawg

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....

Originally Posted by thedak

I can fit 3 fingers in either style of intake port.

Just sayin...

Originally Posted by Shawn @ VA Speed

this def wouldn't be a fair test. the best test would be a ls2 gto a4 car and a l76 g8. I'm pretty sure the gto would have a better sotp feel. like i said before,the square ports need to be on a larger engine.

Originally Posted by thedak

I can fit 3 fingers in either style of intake port.

Just sayin...

Originally Posted by WKMCD

I can fist the WCCH Stage 3 heads...