Alvin

iTrader: (2)

I've got a LS2 I want to put a set of LS3 heads on and I want to get the compression up a little. With this setup and my compression goals (right around 11.5:1 I need to take them down to 61cc. Stock I measured them around to be just shy of 74cc. This seems like a little much to take off. Has anyone done this before? I've heard of guys taking LS3 heads down to 64 all the time.

Thanks

69LT1Bird

iTrader: (1)

You need to re-measure. LS3 and L92 heads are 69-70 cc stock.

anheuserbusch08

iTrader: (11)

the most ill take off those heads is .040 itll put u right around 61-62cc's

WKMCD

iTrader: (2)

Most have best power with a max CR around 11.2-11.3:1 CR. You make not need to take them all the down to 61cc. These heads love timing and too high a CR will not let you run the kind of lead these heads love.

VERTC6

iTrader: (1)

They are suppose to be 68.7 cc and milling .0065 = one cc. What I have been told is to mill around .015 and go with a .040 Cometics gasket and you get a better quench over the stock HG and that will put you around 11.5 : 1, but you need to make sure your cam has plenty of PTV clearance!

69LT1Bird

iTrader: (1)

Before you can pick the headgasket thickness, you need to know how far above the deck the piston is, it does vary, from about 004" - .010"

.035" is optimum quench, so if he is out .005 than the .040 would work. This needs to be checked. Like Vert6 said, PTV will come into play.

Alvin

iTrader: (2)

These heads are definately 73cc. They have been cnc ported by ligenfelter and they must have taken out quite a bit from the combustion chamber

69LT1Bird

iTrader: (1)

"cnc ported by ligenfelter"

Well, you kind of left that out of the first post. That explains the size difference.

I don't think the deck on the head is thick enough to mill that much off. Looks like you need a turbo or blower.

VERTC6

iTrader: (1)

Why did they port out the CC?

WKMCD

iTrader: (2)

My WCCH L92's ended up about 73cc from contouring the combustion chamber. I milled mine .036 and run a .040 Cometics with 2cc pistons .005 out.

hymey

Im at well over 30 deg lead with 11.3:1 comp. Thing is I will still be at 30 deg at peak power zero knock once I go to 12:1 and pick up 15hp. As I see again and again with this cam setup. Your right but then engine doesn't see static compression, dynamic compression is where its at. Listen to the motor what it wants not what someone else got every motor is different. Overlap and gig cams drop dyn comp a lot and hp is left on the table. Mine doesn't knock till 34 deg at peak torque and over 36 up top Its crazy.

See how it goes with compression down how much timing it takes before knock you may only get 28 then if you mill to much your back at 24 and you lose power like Kevvy did. If your at 36 like me with a 240 242 111 and 43 thou quench 11.3:1 comp, I can afford to go more comp and take the free power. So don;t go to far with it, If I had a smaller cam I would be staying where I am but thats not the case!

hymey

Im at 36 thou off chambers are 60cc going to 46 thou and back to a 40 thou gasket which gets here up there this combo loves timing and its at a 107ICL! Really goes to show no two motors are the same but I recommend get the comp right to get peak power at 30 deg timing 25 ish at the dip then right back up to 30. If it still knocks at 30 on the money retard cam timing a couple of deg to drop some cyl pressure. Unless you know the combo its trial and error. I also run an early ICL to keep peak earlier and still need more compression.

PKC-Z71

iTrader: (8)

For what it's worth I've talked to 2-3 engine builders here in the Kansas City area, and all of them agree that the MOST you'd wanna shave off a L92 head is .030, which is what I'm having done to mine.

Daryn

iTrader: (19)

i believe mine are - .040 shaved