What is the best cylinder head out there. I've heard a lot of people going against the l92. I thought it was a good head? they drop off at 6k rpm?I'll be running a stroker and kinda cofused about which heads to run.HELP!

 

I am currently building a 383 LS1 and am using Patriot Performance heads. they are priced well

 

No, the L92 head doesn't 'drop off' at 6000 rpms, not sure who said that...

The one issue that I'm aware of with the L92s is that you can't use the same type of intake manifold with them that you do on the LS1/LS6, etc, because the intake ports are different. The earlier engines use "cathedral port" heads, while the L92 heads have intake ports that are shaped in a more conventional style - more or less rectangular, like big-block Chevy engines. And now that I think about it, I believe I know where the 'drop off' idea comes from - some people were saying that their engines were starting to "nose over" at about 6100, but that's always attributed to the L76 intake manifold. That will quickly be a non-issue, because the word is that FAST is working on a new intake for the L92 heads... And that "nosing over at 6100" problem apparently isn't affecting everyone...

Speaking of big-block Chevys, that's what the L92 heads flow like - we're talking over 300 cfm from a stock as-cast head!! Add in the fact that if you buy them bare, then a pair of L92s will cost you $350, & they just about become a "no-brainer" for a budget LSx build. The total, ballpark cost for buying bare & then buying valves, retainers & all the other stuff to "fill them out" seems to be between $800-$900. (You do need special offset rocker arms for the intake, but I think mine cost me $7 or $8 each, new.)

The three "special factors" that you need to take into account for the L92s are:

1. You have to use them with a bore size of 4" or larger because of the huge 2.16" intake valves (so you can't slap 'em onto a regular LS1);
2. You can't use the std "cathedral port" intake manifolds due to the intake port design;
3. You need to use offset rocker arms -only on the intake side- & one "rocker stand" per head (total cost is probably < $75 new from GM).

(It's possible that I've forgotten something, I'm tired right now - but I'm pretty sure that's pretty much it...)

From what I've been able to see, people have been able to make upwards of 525, 550 hp (sneaking up on 600) from naturally-aspirated engines using these heads & the L76 intake - and once the aftermarket catches up, I'd expect that number to bump up even further.

(NOTE: You're no doubt aware that other vendors such as AFR, Patriot, etc. also make heads for these engines. I don't know as much about those, since the "price point" for those heads is significantly higher - but I've no doubt they're capable of some very good results as well.)

EDIT: Just saw you're building a stroker - for your typical 402 to 440-ish cubic inch build, the L92s will really come into their own, much better than for the stock-cube 6.0 that I'm stuck with...

 

You'll have to run a cam designed for the I/E ratio of the L92 heads. They need more duration on the exhaust side than do most heads.

 

HRM ran a stock l92 head with a stock l76 intake and a crane cam (PN 144HR00119) and made 510 hp (like 465 lb ft I think). Motor had been dyno tuned, and had GTO headers (dynamax i think). The whole article is real interesting for anyone considering a LQ4/9. Starts with bolt ons in the october 07 issue and gets cam/heads in november, than a blower in december. one of my favorite tech issues ever.

 

we are runnig l92 w a tourqer v2 tps cam and l76 intake runs dam good to me

 

I try and keep my eye on the fast cars and see what they run. Last year a lot of the fastest guys were running TrickFlow heads. AFR's are proven and certainly not cheap but I think the L92 design is the future for sure. Its just going to take a little time to get the aftermarket in line for parts that work specifically with them so the weak link factor or compromise issues become moot. Porting, cam, intake etc. Speaking of intakes...


Weiand ( Stark ) has a new intake coming out as well that looks very promising and they claim will be at a better price point than FAST. They are making cathedral and L92 port styles. Supposed to be out in March. Plus theres the new LS3 intake that sounds like its improved substantially over the L76.

I hope this season will be pretty big for L92 style head and product development. It is definitely a growing sector for LSx performance.

As for the L92 naysayers? look at whos bad mouthing them. Its mostly the aftermarket vendors or their cronies. Its pretty darn hard to make a good profit selling 300 dollar heads over 2500 dollar heads. Which would you rather sell if you could?

 

I know I'm either gonna build a 6.0L block with the L92 top end and a custom grind or find a used LS7. haha

 

ACTUALLY... That may not be the case. (I really tried to not "open this can o' worms, but so much for good intentions...)

I've been doing a fair bit of research on which cam to use for the L92 heads, & until recently I believed what you wrote above - and then someone on LS1Tech forwarded me a PM from one of the guys who's been building engines with these heads. Here's a partial quote from that PM:

I'm a little hesitant to post too much of that PM, simply because I haven't had a chance to get in touch w/ him myself yet, & I don't yet have permission to quote him.

At this point, it seems to me that the best course of action would be to do like cam- says, & look at what combos are being used in other cars - and to try to duplicate those that get the best results.

 

So far the jury is definitely out on what is the best cam design to run with the L92's there is a lot of conflicting info floating around. The one thing for certain is they seem to make pretty damn impressive power regardless of what approach is taken as far as cam selection goes. The unfortunate side is finding that perfect fool proof combo has yet to really be decided. For instance its pretty much common knowledge now that if you take an LS1 slap on an LS6 intake, 224-228 cam, stg 2 5.3L heads, you pretty much maximize the reasonable max output from them. There is more to be had but once you crest the 420 rwhp NA area it becomes very costly and you will lose some power under the curve.

My hope is by the end of this year with all the different combos flying around that there will be "L92 heads, this CNC program, this intake, this cam" and voila consistent, flat curve, street usable, big power.

 

That sounds great, cause that's when I should be ready with my build. Although, the only side I see gaining much from CNC would be the exhaust side. From what I've seen, unless you are over 400 cubes, porting these heads is a little useless.

 

True enough

 

You asked "that is the best"

Now without knowing your engine specs...

The answer is none of the above.

call BES or W2W and get a set of All-Pro.

Flow 380cfm good for 800hp n/a 1000hp+FI

See what W2W runs on there Worlds fastest LSX car.

 

Here's what appears to be the beginning of a decent thread on this subject, for anyone interested.

I'd respectfully suggest that we not accept "common knowledge" as established truth - just because it's "common knowledge"...

 

Hey man everything I read is written on the internets so its all true

 

So true. However You won't find to much info on All-Pro heads online. Infact they where a race secret for a long time. But if you see the big name cars many use all-pro.

I have yet to see anyone have flow numbers like they do. I challenge anyone to have a higher flow than these. if so thanks I will buy other.