Gannet

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?

KCS

iTrader: (20)

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.

Jordan S.

iTrader: (17)

I used mahle 3.898's and honed it my self. Runs good so far. Block had 80k on it, factory hone was still visible and no lip at the top of the bore.

5.3LJimmy

iTrader: (10)

It would be wise to hone the motor. The new rings may never seat properly if you install them w/o honing.

Beaflag VonRathburg

iTrader: (176)

As everyone else has said it'll be a good idea to hone them. While you're at it you can throw in some rod bolts and some other little stuff to strengthen it up.

Grimes

iTrader: (3)

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!

RocketCutlass

get it H

Black_98Z

iTrader: (13)

2 fast 2000

iTrader: (4)

I was told anytime you go from a cast piston to a forged you have to bore it.

GuitsBoy

iTrader: (4)

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...

Kamin

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.

Andy1

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