eb02z06

iTrader: (18)

I have on 02 Z06 and was thinking about goiing to the 5.3 heads. Without anywork to combustion chamber what would the compression increase be from the stock 10.5. I believe the stock LS6 heads are 64 cc and the 5.3 heads are 61 cc's. Thanks!

Assassin

iTrader: (3)

just a guess here but I'd say 11.2

Tin Indian

I don't think your question is revelant to the real world. I say that because you won't be installing stock 5.3 heads on the car anyway. The 5.3L heads will need larger intake valves installed since they are smaller than the stock LS1/LS6 intake valves. Also, you will need port work done since the 5.3L head has a smaller intake and exhaust port volume than your stock LS6 head. And lastly, the chambers will need machine work to unshroud the valves. This of course will change the chamber volume, which will in fact increase chamber CCs.

I can tell you about TEA ported 5.3L heads. If the heads are only minimally surfaced .003" to insure straightness, the heads will have a chamber volume of approx 63cc after the CNC machine cuts material in the chambers to unshroud the valves. That 63cc chamber will give you approx a 10.8 to 1 CR when standard GM head gaskets are used.

Below are some of the [stock] specs of an LS6 head vs a 5.3L head:
_____________________________________

Casting Number 243
LS6
2001+ 5.7L Corvette
Material: Aluminum
Combustion Chamber Volume: 64.45cc
Intake Port Volume: 210cc
Exhaust Port Volume: 75cc
Intake Valve Diameter: 2.00 inches
Exhaust Valve Diameter: 1.55 inches

_____________________________________

Casting Number 706
LM4 / LM7
1999+ 5.3L Truck
Material: Aluminum
Combustion Chamber Volume: 61.15cc
Intake Port Volume: 200cc
Exhaust Port Volume: 70cc
Intake Valve Diameter: 1.89 inches
Exhaust Valve Diameter: 1.55 inches

Tin Indian

BTW, you have an LS6. Those are really nice heads to begin with. Why not just have them ported and maybe .020" taken off the surfaces to bring the CR up a little if that's what your after?

eb02z06

iTrader: (18)

Thanks for the info Bro. Let em explain what I was after. First thing was I did not want to increase compression beyond 11. I want to keep it between 10.5 and 10.8. Now i beleive that the LS6 heads have a 210cc intake runner. From what i have seen after porting this increases to 220-230 depending on who does the work. Typical flow figures run in the 300 to 310 at .600 lift. Now the 5.3 head has a 200cc runner that typically ends up being 210to 215 cc after porting and these heads too will flow up to 300 at .600 lift. My thinking is that the head that flows th most with the smallest runner will be an awesome street/strip head-give tons of torque and lots of power with a HR cam. I hope this thread makes a little more sense as to what I was after.

CHRISPY

Most 5.3's see between 290-300cfm at .600 lift @28 inches on 3.905 bore with a 2.02/1.57 valve with anywhere from 220-235cc intake port. (For the majority of sponsors here)
With your combo running as well as it is I dont know if I would change the heads honestly. You will gain "maybe" 2-3 tenths tops. I have 5.3L heads and they work very well but I went from a stock Ls1 head. (124mph on 3514 pound raceweight with .298 cfm at .600 lift)

I would probably run 121mph with stock LS6 heads and my current cam (comparing to what other similar cars have run)

It's up to you I guess if it is worth the expense

Cheers,
Chris

Reboot

iTrader: (5)

I only gained 11 RWHP (Peak) by swapping to TEA 5.3L heads. I lost 7 RWHP below 4800rpm's. In all fairness, I'm not running a big enough cam for the heads though.

A local shop here in Northern California has done many head swaps on Z06's with several of the big name vendor's heads. He's reporting result similar to mine.

Stock LS6 heads flow pretty well. If I were to do it over, I would have kept my stockers on the car.

eb02z06

iTrader: (18)

Chris, my combo may be working well but yours is working better with the 5.3 heads. Your running 2 mph faster than me, plus your race weight is 200lbs heavier than mine. The way I see it-ur car is making at least 40 more horse than me. I agree the LS6 head is probably better-but i'm afraid after porting that the runner volume get's too big and that would only benefit a large cube car. Since u start with a smaller port with the 5.3 head-even after porting it's still smaller so the velocity is kept up which makes for get low end lift and lots of torque. Reboot I don't thinkanything's wrong with ur combo. The LS6 cam is very stout to begin with so u have to go alot bigger to see any real gains from just the cam. I beleive the LS1speed car saw just that-they made 420rwhp withe the stock cam and ported heads.

CHRISPY

I dont know if it is making 40HP more but maybe. Dont forget my combo was optimized as well. 4.10 gears, full slicks, powershifting, very aggressive clutch. Best 1/8th in my car was 98.8mph. Do you have an 1/8th mile time to compare?

thanks,
Chris

eb02z06

iTrader: (18)

My best 1/8 mile is 95.1mph, I know my car is not geared right either Chris. I go through the traps around 5400-5500-way off my 6500 rpm shift points. Your car is making great power bro-no denying it.