I am just wondering what all I need to do in order to put a set of CNC P&P 6.0 heads on my 4.8. Some people say they need to be milled but how much? I am also looking to have a valve job done either a 3 or 5 angel cut. What should I expect from these heads? I will be adding my cam, springs, and stall before the heads go on.

 

Ttt.......

 

im thinking it is 30 thousands but dont quote me on that. i was told anywhere from 30 to 50 ponies from a good set of heads. i have seen about 40 ponies consistently from others experiences.

 

You'll end up losing power. Your compression ratio would drop BIG time, even with a big milling on the heads. Looks like you'd drop to around 8.4:1 compression (8.7:1 milled). Not bad for a blower motor, but a bad choice for a NA motor.

You'd be better off just adding a few bucks and buying a stock 6L to swap in.

 

I am looking for a good 6.0 at a good price. I have just bought a set of 6.0 heads because A few people on the forum told me that would be the way to go. You don't think they can be milled enough to get the stock compression back?

 

good idea, great for a blower, but i dont think it'll drop the c.r. that much, maybe 9:1 and they are pretty much the same as the ls6 heads, except for the bigger combustion chambers for the lower c.r.

i think they're about 74or76cc compared to 64or65cc

 

Do the math.


6L head is 71cc
4.8/5.3 head is 61cc
Roughly 600cc swept volume
Gasket volume is roughly 10cc

CR = (Cyl volume+Gasket volume+Chamber) / (Gasket Volume+Chamber)

STOCK HEADS
CR = 600+10+61 / 10+61
CR = 671 / 71
CR = 9.45:1

6L HEADS
CR = 600+10+71 / 10+71
CR = 681 / 81
CR = 8.4:1