I got a chance to section cut a semi raw head casting and thought I'd share some pics with the board. I started out with a head casting number 5364. BTW does anyone know how many different casting numbers GM made for these heads? I have at least 2 different casting number cores.



Here's a shot of the unfinished chambers.



Note that there are no spark plug holes.

The main purpose of this exercise is to determine how much casting thickness there is in some critical areas of an unported head.

This is a shot of the intake port cross section.



This shot shows the deck thickness.



Note that this casting was not machined to the finished deck height. It was .055" thicker than the finished heads I have. As you can see there's a bit less than 1/2" of material supporting some of the head gasket sealing surfaces.
The back wall of the the chambers seem to be thick enough as evidenced in this shot. It looks like a little over 3/8" wall thickness here.



Several thin spots surrounding the intake and exhaust ports are evident. This shot is looking at the back of the intake bowl on one side of the guide boss.



And heres a look at the as cast exhaust port section.



Note the lack of roof section thickness here:



If I come up with any more relavent pictures I'll post 'em up.


Richard

 

hm, rather interesting. i guess people need ot be a lil more careful than usual or is a lot of this a usual thing with stock casting?

 

There enough room there to get that exaust port flowing where it should be in comparison to the intake? Looks a lil thin maybe?

 

Thanks Richard. This info is one of the reasons I didn't rush to have the L92's ported for my build. I'm waiting for a proven CNC product.

 

Very informative. Thanks Richard. Do you have some comparison measurements from GM and aftermarket LS1 style heads? Do GM LS7 heads (and aftermarket variants) share the thin issues?

Thanks,
Bill

 

When I got my heads we noticed that the valve seat seemed to have a lot of extra material in it. Could you take material out of the areas I circled to improve flow? The opening appears to be smaller than the valve right there, and not by a little.

-Geoff

 

This example is pretty standard for factory parts including the LS7 heads. I'll try getting some shots of other heads to post up in the near future.
No doubt there's working room to improve airflow in these heads, but I wanted to note the ultimate short coming of these heads. That being said, they're still an impressive part from a major automaker.

Richard

 

These heads did not have the steel seat rings installed. That's why the casting is pinching the port at the seat area. Once the seats are installed the thickness in that area will be less.

Richard

 

I'll be keeping an eye on your future input regarding these heads Richard, hopefully you will be able to offer something nice for all out race applications.

 

Thanks Richard,

Great info. I agree I wonder how they compare in strength i.e. thickness to Ls6, Ls2, and Ls7 heads. I'm glad there are sponsors/vendors like yourself that are willing to do the homework and share tech. knowledge with the rest of us. Many don't. Can't wait till you offer different L92/L76 packages.

 

Ricahrd

do you see any issues with th head being able to handle a solid roller spring with 300+ seat pressure

 

Those unfinished chambers are nasty. You might not be able to go crazy on the runners, but you sure as hell can there. Definetly could pick up some major flow there.

 

I building a F2 blown motor and was going to switch from my LS6 heads to the L92 heads. The main reason I cannot is they dont make aftermarket rockers for the head. I called W2W, Jesel,T & D and SDPC no rockers. At SDPC they havent even heard of any talk of rockers any time soon. W2W siad they would not recommend the stock rockers with anything over 200psi on the seat

 

Jesel e-mailed me a few months ago on the L92 rockers. The thread is here https://ls1tech.com/forums/showthrea...ight=jesel+l92

 

after seeing these pics, looks like most of the gains are going to be had doing work well within the port, that cleaning up the entry and 2" into the runner will be for cosmetic purposes only.

 

I'll call them back with that info, but as of yesterday they dont have a set. Jesel and T & D can both make a one-off custom set if you send them your head, but i dont want the L92 head that bad.

Side note...How do you like that TDI Volkswagen?

 

Thanks a lot. I am working on a set right now and it is nice to get an idea how thick the walls are in various places. Chuck

 

So do we think a .030-.040 mill is ok ?
Also in the GMHP article it mentioned you should use a 4.065 head gasket on a LS2 because the 4.03 hung into head in one place ??
Thanks

 

That has been several months ago so maybe they've changed their plans. On the VW, it's a great car. I'll probably never own another car for a DD. It'll get 50 mpg if you'll leave your foot out of it, but believe it or not, it's got some power. The turbo really gives it some oomph. I hope to put half a million miles on it before I have to have any major overhaul on the engine.

 

That makes 2 of us.