New pistons without boring?
Thread Starter
12 Second Club
Joined: Mar 2006
Posts: 302
Likes: 1
From: Sarasota, FL
New pistons without boring? There are many reports of LS-1 engines with 100k+ miles showing the original cylinder crosshatching, or being tight enough to take FI. I have a stock '02 LS-1 with 30k miles. It makes excellent power, so I assume it has good seal.
I want to install a Kenne-Bell. Although the 7 psi base boost setting would probably hold me for quite a while, I really would feel better going with forged pistons. So now the question: assuming that leakdown and compression tests look good, is it likely that I can successfully swap in forged pistons in the stock bore size and not have to bore the block? SDPC offers a Speed-Pro piston set that seems designed for this purpose: 3.898" Bore, LS1 / LS6 5.7L Forged Piston and Ring Combo.
Anyone else done this?
I want to install a Kenne-Bell. Although the 7 psi base boost setting would probably hold me for quite a while, I really would feel better going with forged pistons. So now the question: assuming that leakdown and compression tests look good, is it likely that I can successfully swap in forged pistons in the stock bore size and not have to bore the block? SDPC offers a Speed-Pro piston set that seems designed for this purpose: 3.898" Bore, LS1 / LS6 5.7L Forged Piston and Ring Combo.
Anyone else done this?
I'm sure it would run, but it would be better to just get it honed with a torque plate and get the more common 3.905" pistons which are about the same price. This way it will seal better, and seal longer if the machinist does a good job.
BTW, it doesn't need to be bored, just honed.
BTW, it doesn't need to be bored, just honed.
I remember seeing somewhere a microsopic comparison between freshly honed and broken in cylinder walls. The freshly honed picture had nice sharp microscopic ridges, while the other didn't. I'm assuming this difference is needed to break the rings in properly. So get it honed!
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Good one RocketCutlass
You do need a fresh hone to get the rings to seat properly... That being said, you can simply use a bead hone to just give the cylinder a bit of texture without taking much if anything off the cylinder wall (assuming theyre not out of round). Then you can install your 3.898 pistons and go. People have done this to motors for years. Its not as precise as a fresh bore and hone w/ torque plate, but it gets the job done. Since youre going FI, youll likely need a little extra piston to wall clearance anyway, and a quick hone will give you just that.
Now Im going to get my *** flamed by all the perfection ****'s...
You do need a fresh hone to get the rings to seat properly... That being said, you can simply use a bead hone to just give the cylinder a bit of texture without taking much if anything off the cylinder wall (assuming theyre not out of round). Then you can install your 3.898 pistons and go. People have done this to motors for years. Its not as precise as a fresh bore and hone w/ torque plate, but it gets the job done. Since youre going FI, youll likely need a little extra piston to wall clearance anyway, and a quick hone will give you just that.
Now Im going to get my *** flamed by all the perfection ****'s...
TECH Apprentice
Joined: Jan 2006
Posts: 369
Likes: 0
From: Phoenix, AZ
Originally Posted by 2 fast 2000
I was told anytime you go from a cast piston to a forged you have to bore it.
not bore, just hone.
+1 more for honing, dont worry about boring it unless you have the block checked and a cyl is a little bit out of round.
TECH Resident
Joined: May 2004
Posts: 792
Likes: 2
From: SoCal
A forged piston expands more than a cast piston, so it needs more clearance. I'm going to assume the forged piston is for a specific bore application, but it would be best to talk to the piston manufacturer in that regard.
Andys
Andys
