Anyone with a 4.8 or 5.3 have these?

Musclemax500 · October 26, 2004

I just got the 2004 GM performance parts catalog and noticed in the chevy "GEN III Design" section on pg 104. It has these LS6 Heads "CNC Ported" for the 4.8,5.3, and 6.0 Gen III V8. Does anybody with these motors have them and if so how much of a difference it made in performance?

-Mike

P.S

How more power will these give my 4.8?

Musclemax500 · October 26, 2004

Here is what im talking about. Look at the very bottom of my page.

My Webpage

99Silver6.0 · October 26, 2004

Here is what im talking about. Look at the very bottom of my page.
My Webpage

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If you use them it will drop your compression. Wrong direction to go for a perfromance increase. The chambers are bigger than what are on the 5.3 heads. If you mill them, and im not sure you could mill enough off to safely get back to compression of the 5.3 heads, you could get the ratio back up. Just look for a set of stage 1 or 2 5.3 heads and go that route. That or get your heads ported, polished, blended and milled a bit. You should be really happy with the outcome of that. Most LS1 guys buy 5.3 heads and get them worked over and slap 'em on.

Musclemax500 · October 27, 2004

Thanks for the reply. How much more power would i expect from the 5.3 heads?

Can i put the 5.3 heads on my 4.8 with no prob?

Musclemax500 · October 27, 2004

I just got the 2004 GM performance parts catalog and noticed in the chevy "GEN III Design" section on pg 104. It has these LS6 Heads "CNC Ported" for the 4.8,5.3, and 6.0 Gen III V8. Does anybody with these motors have them and if so how much of a difference it made in performance?

-Mike

P.S

How more power will these give my 4.8?

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How does it lower compression when it says its made for our motors?

99Silver6.0 · October 28, 2004

I just got the 2004 GM performance parts catalog and noticed in the chevy "GEN III Design" section on pg 104. It has these LS6 Heads "CNC Ported" for the 4.8,5.3, and 6.0 Gen III V8. Does anybody with these motors have them and if so how much of a difference it made in performance?

-Mike

P.S

How more power will these give my 4.8?

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How does it lower compression when it says its made for our motors?

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Bud, it is made for our motors. But you need to understand that the dome size of the heads on your 4.8 and on an LS6 are totally different. If you put heads on your 4.8 that have a smaller dome than a stock 4.8 you are going to decrease your compression. Vice versa with heads and smaller domes, the compression will go up!

TarheelZ · October 28, 2004

You could be right, but it could also mean that the heads for the 4.8L have already been milled sufficiently to maintain or raise CR.

99Silver6.0 · October 28, 2004

You could be right, but it could also mean that the heads for the 4.8L have already been milled sufficiently to maintain or raise CR.

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LS6 heads and 4.8 heads are in fact different. The 4.8 and 5.3 are 63CC chambers. Whereas the 5.7 LS1 chamber is 67cc, the LS6 is 64cc. 6.0 heads are just bigger chambered LS6 heads at 71CC's.

TarheelZ · October 28, 2004

I get what you're saying about the differences. It's certainly possible that the description in the catalog was just a misprint...or maybe it's for real and they've already prepared the heads as necessary for each block.

99Silver6.0 · October 28, 2004

I get what you're saying about the differences. It's certainly possible that the description in the catalog was just a misprint...or maybe it's for real and they've already prepared the heads as necessary for each block.

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Id bet they are just plain old stock LS6 heads, 317 castings. Unless they will mill them for you after purchase. But I dont think they would mill LS6 heads for evey LSx based motor out there. Thats alot of different mill specs.