Question about deck height
Question about deck height ok i didnt know exactly how to title this so bare with me.
im building a forged 99 LS1 block with a stock crank, callies compstar rods, and probably malhe forged -4cc pistons. its going to be an NA setup with nitrous later on. im planning on a Torquer 2 cam and a set of custom ported and polished LS6 243 heads with a fast intake.
when i have the block machined im only hoping for a .005 overbore and some cleaning up. ill deck the block if i have to. but what about recessed pistons or pop up pistons? i have no idea where to even start reading about that, can i get some help?
im building a forged 99 LS1 block with a stock crank, callies compstar rods, and probably malhe forged -4cc pistons. its going to be an NA setup with nitrous later on. im planning on a Torquer 2 cam and a set of custom ported and polished LS6 243 heads with a fast intake.
when i have the block machined im only hoping for a .005 overbore and some cleaning up. ill deck the block if i have to. but what about recessed pistons or pop up pistons? i have no idea where to even start reading about that, can i get some help?
The pistons might end up in/flush/out of the bore. They are all ok, but it does affect the quench height (piston flat spot to head flat spot clearance). Most guys seem to shoot for .030"-.045" in this area. You can either deck the block to bring the piston up or use a thinner head gasket.
TECH Resident
Joined: Aug 2004
Posts: 875
Likes: 2
From: Portland Oregon
With LS1, the problem may be that some pistons stick up too far so be careful not to deck the block unless you really need to. I bought custom pistons and set the height at 0 with a new block, with a .040 head gasket.
i dont want to deck the block if i dont have to but figured i would shoot for the worst and hope for the best. how do you set the height at 0? if it helps any, im going to be running stock MLS head gaskets.
You could either deck the block to bring a piston thats in the hole up to flush with the deck or see what your deck height ends up being and order custom pistons to move the pin around to get it closer to flush. I'd shoot for ~+.010 out of the bore to give you .045" quench with those stock MLS gaskets.
Many aftermarket motors use out-of-bore system, meaning the pistons stops slighly above the deck, negative deck height. Around .01" is fairly common, .02" is max and probably not reccomended. Negative deck height helps keeps the combustion in the combustion chamber and not in the cylinder, which mean more power.
what is the benefit of not having the piston come out of the bore? i mean if it makes more power in an out of the bore situation, is it safer to run it in the bore or something? also is this something im really going to have to wait and talk over with my machine shop? i dont want to order custom pistons if i dont have to as im trying to keep costs down while keeping a quality part.
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Originally Posted by 1bdbrd
what is the benefit of not having the piston come out of the bore? i mean if it makes more power in an out of the bore situation, is it safer to run it in the bore or something? also is this something im really going to have to wait and talk over with my machine shop? i dont want to order custom pistons if i dont have to as im trying to keep costs down while keeping a quality part.
