Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner

21 - 33 of 33 Posts

·
Registered
2006 chevy
Joined
·
68 Posts
799 heads

those heads are on our 07 tahoe and 06 silverado, both 5.3l, not 6.0l... my 06 tbss has 243's... i just cant see how the same casting can be used on two different displacements.



:weird:
 

·
Registered
Joined
·
136 Posts
those heads are on our 07 tahoe and 06 silverado, both 5.3l, not 6.0l... my 06 tbss has 243's... i just cant see how the same casting can be used on two different displacements.



:weird:
In the Gen-III & IV motors GM has gone to changing piston dish sizes rather than head chamber dimensions to control compression ratio; it's cheaper in a manufacturing sense. Example in Silverados (Vortec motors) is the 6.0L LQ4 & 6.0L LQ9, they are identical except for the pistons, the LQ4 has less compression (low compression pistons) than the LQ9 to run primarily on 87-octane.

Mr. P.
 

·
Registered
Joined
·
99 Posts
those heads are on our 07 tahoe and 06 silverado, both 5.3l, not 6.0l... my 06 tbss has 243's... i just cant see how the same casting can be used on two different displacements.



:weird:
A casting is just that... a CASTING. The real story is the part number on the head. Probably behind the accessorys on drivers side and against the firewall on passengers side.
 

·
Registered
Joined
·
186 Posts
I can't check my TBSS as it is in the shop having the rear end replaced (long story). So I took a look at my '05 SSR (same engine), has 243's on both sides.
 

·
Registered
Joined
·
37 Posts
This is much ado about nothing. The different casting numbers are because two vendors are now making the heads for GM. The only difference is they originate from different vendors. They are built for GM to the exact same spec. Same thing is happening with L76 heads.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #32
The Corvette folks are still pursuing this issue. The latest info showed GM has these listed as two different part numbers, and the 799's for the LS2 are marketed as the high flow heads for the previous Z06, even one item said not for street use. So nobody knows for sure, and may not be a big deal.

The odd thing is that GM can't , hasn't, or won't answer what the deal is yet.
 

·
Registered
2005 chevy trailblazer_ls
Joined
·
1 Posts
casting number location

I have a 05 Chevy trailblazer that need a new head. I went to the auto parts store and they asked for the casting number on the old head. Does anybody know where that is. I need to get my Trailblazer backon the road.
 
21 - 33 of 33 Posts
Top