Evening ladies and gents

I had a 2010 Chevy 1500 crew cab as an insurance vehicle that I got to drive around for a few days. I checked the engine bay and was looking over the specs for the newer 5.3's that come in the GMT 900 trucks. It appears that the 5.3 in my truck had 243 casting heads. Normally,these heads are LS6/LS2 casting and have 65 ish CC chambers which would really lower comp ratio on a normal 5.3. The new 5.3's are rated at 315 hp so does this mean that the new 5.3's are all like the HO all aluminum L33's from the SSR's a few years ago? Do they have flat top pistons or are the heads milled to make up the comp ratio?

 

Flat tops.

 

it's a ly5(5.3) with 243/799 heads . only difference on the ls2/ls6 heads are the valves..
and its a IRon block, and 315hp' rated to crank... not @ wheels...

 

So when you say the valves are different, do you mean size? Or do you mean that they are not of the sodium filled variety?

 

Yeah, The Valves are Not sodium filled like the LS2/LS6.

 

^^^ but with a 3/5 angle valve job+ ferrea valves and some porting .. . "now were talking" . . .

 

The only sodium filled exhaust valves were on the LS6 "243" heads that made it into the 2002-2004 ZO6 Corvette motors. All other LS6/LS2 - engines that use the '243' cylinder heads use standard exhaust valve materials.