forged pistons installed
Thread Starter
Instructor
Joined: Apr 2012
Posts: 107
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forged pistons installed
Hi guys just had a set of oem style forged pistons installed after the pistons broke in cylinder 3 and 5 on the driver side, because of a stock cat failure. Got the car back and break in is over, but i have never had a car with motor work like that done and it just seems like the pistons are loud i dont really know how to describe it but its not a ticking or knocking theyre just loud is this normal?
Racer
Joined: Feb 2008
Posts: 326
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From: Norman OK
It is normal for a forged piston to make noise referred to as piston slap.
Forged pistons require more piston to wall clearance because they expand more when heated than traditional cast pistons. So they tend to be much noisier when cold. Some will even be noticeable when hot.
Anyway to get a video? How is the oil pressure? There are a lot of noises that come from a motor. Did you do a cam or valvetrain work while the motor was apart?
Forged pistons require more piston to wall clearance because they expand more when heated than traditional cast pistons. So they tend to be much noisier when cold. Some will even be noticeable when hot.
Anyway to get a video? How is the oil pressure? There are a lot of noises that come from a motor. Did you do a cam or valvetrain work while the motor was apart?
Racer
Joined: Jun 2012
Posts: 440
Likes: 6
From: Hillsboro Oregon
I'm a little confused. Are OEM pistons forged or cast? My `08 LS3 has a bit of piston slap until it reaches operating temp. Sounds like a diesel truck when cold. Not sure what the OP means by "OEM style forged pistons".
Racer
Joined: Feb 2008
Posts: 326
Likes: 0
From: Norman OK
I'm guessing he meant stock size. Not sure.
LS3 pistons are cast. Just about all factory pistons are cast.
That being said there have been complaints about piston slap in factory motors ever since the ls/gen3 came around. My 5.3 truck has nearly 200k on it and rattles a good bit when cold. Still runs great. I just don't abuse it until it warms up.
My ls3 does a bit if it is really cold.
By contrast my forged lt1 (all aftermarket) has a lot of clearance and still rattles a little even once warmed up.
LS3 pistons are cast. Just about all factory pistons are cast.
That being said there have been complaints about piston slap in factory motors ever since the ls/gen3 came around. My 5.3 truck has nearly 200k on it and rattles a good bit when cold. Still runs great. I just don't abuse it until it warms up.
My ls3 does a bit if it is really cold.
By contrast my forged lt1 (all aftermarket) has a lot of clearance and still rattles a little even once warmed up.
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