Looking to upgrade my 241 heads to either the TSP PRC Stage 2.5 5.3L heads or the PRC Stage 2.5 LS6 heads. Curious to know what the difference in gains would be between the two on my current set up and what typical gains are with the two on a set up like mine. Which is: 01 Z28, 48K, M6, full bolt-ons, TV2 cam and fast 90/90. Thanks for any help and recomondations.

 

GFK, there is plenty info in this forum archive. Same Q has been asked before many many times. Perhaps a little bit of 'search'.

 

In the time it took you to respond to this, you could have probably answered my question. Smartass.

 

From everything I've read it seems like you can get better flow #s from the ls6 heads. And if you wanted the 5.3s for better compression you can always mill the 243s. I'm going with the 2.5 LS6 heads milled to about a 62cc chamber to up the compression some and still give me ptv clearance.

 

Both will be within 5 to 10 hp of each other. I gained 48rwhp/21tq after I added the 2.5 5.3 heads to my 228R cammed car.

 

I wish people would avoid saying that a CNC ported 5.3L head has more compression and that is why they should be used.
Guys a CNC 5.3 is at least 63cc/64cc in the chambers and 243/799 around 64cc/65cc.
So 1 cc hardly makes a huge difference to be a factor of choice.

 

When it comes down to it how do you know which to choose in the first place? Either one you go with you can change up the intake runners the same, valves, and exhaust ports. Does one have more meat on it than the other rendering it "stronger" or more modifiable?

 

I also meant to add in combustion chambers to that list.

 

Ls6 and dont look back. Good luck with your built.

 

OP and SoonerBrad, There's probably more difference in the different porters around the country than there is in the difference in these heads from the same porter after they've been ported. 241's, 243/799's, 862/706's are all good LS heads for stock cubed LS1's and all known porters around the country can set you up well with any of them. Your goal, budget, and combo are what you need to match. I'm running TSP 2.5 LS6's and I had my doors blown off by a friend the other day running TSP 5.3's. Difference? It wasn't heads. Cam and setup were the difference. My cam is drivable, and pretty mild, his just short of an MS4.

Also, I'd encourage you to look at (I know this is dangerous Predator) flow numbers of different porter around the country and look for the "under the curve" numbers not just the peak numbers. Rarely, will you ever use up the 324 CFM the (insert your head porter here) heads has @.650 lift. As a matter of fact, if your cam doesn't lift to .650 (just an example) you'd never use that flow! Look at the flow @.300/.400/.500 lift and see what each head produces.

All this said, the LS6's are the most marketable if you ever look to sell them after using them for awhile.

 

LS6 heads are much better heads to begin with. There's only so much you can do to 5.3L heads to make them as good as LS6.

I'd go LS6... but Stage 1 from TSP. You won't gain much going to the heavier aftermarket valves. What you will lose is piston-to-valve clearance and add additional weight to the valvetrain. It's also the cheapest option.

 

I also like to consider the intake runner cc as two heads that flow the same with one having a smaller intake runner will equate to more power in the real world because of better port velocity.