Nitroblood

I have both in the garage waiting to be used. The plan of course was/is to port-polish, the one I eventually choose. And sell the other.
I know about the compression increase with the 4.8 (similar to 5.3) and the flow of the 6.0. Are there any other similarities/differences?
I will be using an '02 LS6 cam w/'01 LS6 springs. Would I need anything else, between the two heads? Pushrods? Rockers?
The biggest difference I can contribute is the weight. The 4.8, of course are aluminum, the 6.0's are iron.

** Any advice and help is appreciated. Just trying to get the most for less out of my stocker 346!

DenzSS

Both are bad choices. I'd scrap them both. Too much work to get the 4.8L to a reasonably usable state and you'll pay too much to get the 6.0L iron heads ported.

You can get a set of 5.7L heads for next to nothing and do whatever porting you want.

JZ'sTA

iTrader: (23)

Big disagree here. The 4.8 and 5.3 heads are exactly the same. They even have the same casting numbers. Therefore why would they be a negative?

I do agree with the iron 6.0 heads, and didn't even know they made these heads. What is the casting number on the heads?

The 4.8/5.3's should work best. The 317 6.0 heads do flow better and are lower compression. If you had a set of these they would work nicely and be great if you even decited to bolt on a charger or Turbo b/c of the lower C/R.

DenzSS

Had no idea. I thought the 4.8s had a smaller chamber than the 5.3.

Aren't there some issues with the chamber size on the 5.3?

Nitroblood

Well, JZ, if I found the right number on the 6.0's, the casting number is 873. Plenty of other numbers etched into the head.

I got these heads not fully aware of the aluminum version available. I just saw 6.0 and grab them. Oh well, know of anyone wanting 6.0 Iron?

I didn't post this thread for opinion, I just wanted to know pure raw information on what I had, and what it's being combined with. Thanks for the back up on the 4.8s, JZ.

TEA Brent

The iron 6.0L heads are basically a 5.7 head cast in iron, but with water jackets put between the int and exh bowls which further restricts the port flow. I just threw a set of those away. The 4.8/5.3 is the best castings to have short of a LS6 casting. We have had customers make 450+ RWHP with the 4.8/5.3 castings properly ported, and the 5.7 castings (aluminum) have only made about 430 RWHP, both with streetable cams in the 230 @ .050" duration range or less. I will attach a graph of our current Stg 1.5 4.8/5.3 vs our current Stg 2.5 LS6 heads, the higher tq and hp #'s are of the LS6 Stg 2.5 heads. Hope this helps.