Milling LS3/L92 heads for LS2
Milling LS3/L92 heads for LS2 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
Thanks
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.
Last edited by WKMCD; Dec 19, 2009 at 12:19 PM.
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!
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.
.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.
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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.
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.
Last edited by 69LT1Bird; Dec 18, 2009 at 06:01 AM.
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TECH Apprentice
Joined: Jan 2008
Posts: 366
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From: Gladstone, Queensland, Australia
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!
TECH Apprentice
Joined: Jan 2008
Posts: 366
Likes: 0
From: Gladstone, Queensland, Australia
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.
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.
