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 controlled variable...... a camshaft would be a independent variable.....

So explain bro....?

 

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 wonder how many pages this will get to?

 

There's a good thread at LS1GTO that details the results of swamping from the OEM 243s to L92/LS3 heads. One of the posts has compiled the dyno results of 22 people who have made the swap, along with a notation if any port work has been done on the heads and/or intake. None of the swaps so far have put up bigger numbers than what I've seen from ported 243s, much less an aftermarket cathedral head.

And FWIW, I jumped on the L92 bandwagon as well. I have a NIB set of L92s sitting on a shelf in my garage. For the time being I'm going to stick with my ported cathedral heads.

 

It should be obvious that, in most cases, the raised runner l92/ls3/ls7 heads are going to be more efficient in regard to racing the flow bench. Anytime you straighten or improve the trajectory of a passage you tend to bump its efficiency. That can clearly translate into improved performance. However, that doesn't necessarily mean it is ideal for a particular application. To select a head on that basis alone, ignoring other critical aspects such as available chamber volume ranges, available p2v, value to the customer etc. is fine for discussion. However, in real life it often will not lead one to the "best" compromise in our experience.

As is often the case, either style can be made to work, and work well. For example, if you already own a set of 243's and your goals are in the 450-500rwhp range, then you already own the potential to get there without going through the expenditure of a swap to l92/ls3's (or aftermarket castings for that matter). However, if you don't, then the l92/ls3's can be a great value ($/potential & longevity) depending on the work applied to them. We have programs for TFS/Dart/etc. aftermarket cathedral castings, but it is a rare application that we suggest them over a GM casting. There's plenty of potential in them provided you know where to look.

It is more the indian than the arrow.

-Phil

 

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.

 

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.

 

That's very true and again I want to emphasis that the point of this is not to **** on cath. port heads. Lately I've been fielding a lot of phone calls and emails from people who are scared of square port heads due to some of the blanket "cathedral port are better than square port head" statements they've been reading online so when I saw this article I found it very relevant.

 

My L92s had great results. Setup and the builder go a lot further than port shape alone.

 

I dont mean to side track here but I think its most important to recognize a KEY fact that i dont think anyone is saying L92 heads are better than all other comers because they arent. Where they absolutely shine in comparison is their PRICE. Sure there are many heads that make better power but at a much greater cost. The game of horse power is simple...

How fast to you want to spend?

For this reason alone they are worthy of all of our respect

 

It's proven in the posted dyno, the real deal, it's not all about airflow like you think..a big part of it is airflow speed. Putting heads that were designed designed for a 6.2L engine are going to be oversized on a 5.7L. That is why mast came out with 245cc runner square port heads. GM will also sooner or later make smaller runners for the 4.8 and 5.3L engines. Hopefully for the 5.5L that will replace the LS3 too.

I agree the mast 245cc square ports on a LS1 with the same intake setup will mostly outpreform the AFR 225cc cathedrial heads everywhere on both torque and horsepower since it's a cleaner design...

 

No, he is saying that a $750 pair of heads out performed a $2300 set of heads. One is a stock casting and one is an aftermarket casting. One has GM R/D the other has the backing of GM R/D along with AFR R/D. Which one do you think should be the hands down winner every time?

Its just like the lady gaga arguement. Its not the fact that she does not have a penor that is the problem, its the fact that everone questions whether she could or not.

 

Yea, I was expecting near perfect cathedrial heads to match bigger stock casting square ports. FYI it only costs GM about $150 per head in manufacturing costs.

 

Where do you get your GM cost data? Last time I checked, they keep actual costs of production quite close to the vest.

What is probably more important is what we can purchase a head for. It's like $13.00 rocker arms from GM. Cheap for us, but one hell of a markup from actual production costs.

Jon

 

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.

 

No,.... No one said putting l92's on a 5.7 for one very important reason, you cant, the valve will hit the block.... This was simply about square ports, on engines designed for them.

 

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.

 

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

 

 

Good point...but you have to understand, the L92 is a STOCK GM part. The AFR's are an aftermarket piece. Compare prices for both sets of heads. You can buy a set of L92's and CNC port them to out-flow most of the aftermarket heads for way cheaper than purchasing a set of aftermarkets...

I think that GM, again, has done a great job in R&D for the L92 heads. All of us "do-it-yourselfers" can just purchase a set, get the bolt-ons and install them without breaking the bank. I'd rather invest $900 in my L92 any day then spend the $2000 for a set of heads for a daily-driver or a weekend toy, as many of us have, with week-end "go-fast" budgets...