Re: Forged Piston Noise when cold, Piston material or pin placement?

[biljoh@xxxxxxxxxxxx]

  Bit Nick forged pistons are noisier when cold because of the clearance it has nothing to do with the "material" of the piston making the noise rather the machining required to compensate for the greater expansion of forged pistons. The LS1 piston slap is a documented example of this and is considered normal. I dont think yukons have Ls1's in them?

On October 6, 2004 Alfano,Nick wrote:

> This is a false statement.  Forged pistons do not make more noise during start
> up than cast pistons.  It has more to do with piston to wall clearance> Nick Alfano
> 
> 
> --------------------------------------------------------------------------
> 
> Date: Tue, 05 Oct 2004 22:17:38 -0400
> From: biljoh@xxxxxxxxxxxx
> Subject: Re: Forged Piston Noise when cold, Piston material or pin  placement?
> To: mail@xxxxxxxxxxxx
> Message-ID: <ADVANCES62A1XvpFVjC0000003e@xxxxxxxxxxxxxxxxxxxxxxx>
> 
>   Forged pistons will make more noise on a cold motor than cast pistons until
> the engine warms up.  I would imagine that as the engine wears over time the
> cold noise could get louder/worse as the cylinder wears increasing the
> clearances even more. "over .003" could now be over .005. Piston side skirt
> wear and cylinder lning wear combine.  This is a common problem on modern
> engines using forged pistons most notably LS1 motors that have had lots of
> comlaints about piston slap on start-up. The pin placement may or may not make
> the situation worse I have never researched that but someone here will be able
> to adress that.
> 
> 
> 
> 
> 
> .


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