CNC L92 heads

[Dr. Glock]

from the GM Performance parts Cataloge:

88958698 CNC L92 material-Aluminum Port Size-279 Valve angle-15 deg Chamber CCs-68 Intake valve-2.165 Exhaust valve-1.59 port type-L92 Std LS Bolt-down Solid stem valves 206

The stock L92 heads port size is 260 and chamber size is 70 CCs.
The CNC L92 heads can be had for about $600.00 each at Pace Performance.
I think after considering everything including replacing the block with the LS3 427 from Pace, I'm going with the Livernois DOD delete/Stage 1 cam/tune, GMPP CNC L92 heads, and ARH long tubes, and a home fabricated CAI. If I get bored or want to race it at the drag strip I'll go for some forced induction (probably turbocharging) and a diff change (3.45).

The combination I enumerated above is what i think the factory probably would have done if they did't have politicians designing their cars for them.

Has anyone used these heads? Andy at Livernois or Crazy Paul know anything about these heads?

[Crazy Paul]

Here's the stock L92 head flow data from GM
http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/L76/L76-L92headflowdata.jpg

& here's the CNC L92 head flow data from GM
http://i2.photobucket.com/albums/y20/PerthPurplePenguin/car%20parts/L76/CNCL92headflowdata.jpg


Two things worth noting, the CNC heads were flowed on a bigger bore,
the exhaust flowrates of the CNC heads appear to be worse at partial valve lift all the way up to about 0.450".
It would be interesting to see them both tested on a 4.000" bore.
The 2 cc reduction in chamber volume might raise static compression from 10.4 to 10.6 or so.....which in itself, may produce a 5ishHP gain.

IMO on a stock displacement L76 you already have ample intake flow, the stock LS3 intake and stock L92 heads can flow more than enough air to produce the type of power 95% of you guys are chasing.
Sure ported heads and ported intake manifolds can help raise efficiency, and may free up 15-20HP or so, in combination with a great cam.......but for $1200 you could probably find the same power gain by nailing the tuning aspect, or by concentrating on intake and exhaust piping. The later approach would probably be more beneficial over the entire rev range and not just at the top end.

eg: Compare a 6.0 LS2 with untouched L92 heads (10.4 CR) and a Livernois Stage 1 cam [450rwhp] in a 2006 GTO to results so far obtained with similarly cammed G8-GT's. I think there's a squadron of missing horses to be found in the G8-GT without touching the heads.

Another good example would be this (LS3 heads are basically L92 heads with different intake valves):
http://www.forum.grrrr8.net/showpost.php?p=27338&postcount=53

[Master8ter]

:watch:

I love reading tech like this, It helps me decide what to do when I finally get money. Better information means making a better decision.

[MANOFSTEEL69]

Livernois can also make the heads, so if you go the route of Stage II with them, you might as well have them do the heads as well.

[Andy@Livernois]

I am surprised on the relatively low flow numbers... our's flow 360/245 (275 with a pipe) I have been toying around with the idea of cnc'ing just the exhaust side, and doing a good valve job on the intake... The CC of the intake side is already big for a 6.0, but the exhaust definitely needs some help...

i am trying to find the sheet that has the incremental flow numbers for our L92 heads, it's still packed away from PRI last week...

[MANOFSTEEL69]

Andy.....Get Matt off his butt and on my numbers! :) Before Momma loses interest in letting me make my car faster :)'

[Andy@Livernois]

I will work them up for you... I know he has been busy, just make my PM box bigger :D

[Dr. Glock]

Thanks Crazy Paul!! Your opinions are always data-rich, nutritious with information for tech starved puppies like myself. Crazy Paul is never biased...just the straight dope from OZ!

[R.Penguin]

Thanks Crazy Paul!! Your opinions are always data-rich, nutritious with information for tech starved puppies like myself. Crazy Paul is never biased...just the straight dope from OZ!
If he ever lies his pet wallaby kicks his ass. :p

Yes, the wallaby does have internet access.

[Dr. Glock]

I'm trying to post the picture of Crazy Paul's fabulous ass-kicking wallaby Crazy Harold.