I have a 84mm ls vtec and it has some piston slap when cold. I have heard that cp pistons shouldnt make very much noise if any. Is this true or should I pull the motor out and take a look it?

 

how much slap?

 

cold piston to wall slap noise is common in low silicon hi expanding 2618 aluminum. However what is the piston to wall clearances?

 

I am not sure. I had golden eagle build the short block so it is set to what they set it to.

 

My vitaras sound like a diesel and it runs fine.

 

CP's do not slap unless the wrong piston to wall clearance is bored into the block. You would need to let us know the EXACT bore size of your block by measuring it, not what they told you it was.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by program &raquo;</TD></TR><TR><TD CLASS="quote">cold piston to wall slap noise is common in low silicon hi expanding 2618 aluminum. However what is the piston to wall clearances?</TD></TR></TABLE>

I think that is backwards. high silicone has a high expanding rate. not low... but

 

Is it something to worry about? Do you think that i should pulll the motor apart?

 

I was also wondering if maybe they set them up lose since it is a turbo motor? Do you think that it could be a cracked skirt or something like that?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by earl &raquo;</TD></TR><TR><TD CLASS="quote">CP's do not slap unless the wrong piston to wall clearance is bored into the block. You would need to let us know the EXACT bore size of your block by measuring it, not what they told you it was.</TD></TR></TABLE>

is that the case for every scenario?

i know i hear it alot when its below say 45 degrees out

 

Does it go away when the motor warms up? being that it is forged, this should be the case...

 

nope..

low silicon pistons require bigger clearances, hence, knock more when cold

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMs1eeper &raquo;</TD></TR><TR><TD CLASS="quote">I think that is backwards. high silicone has a high expanding rate. not low... but </TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JDMs1eeper &raquo;</TD></TR><TR><TD CLASS="quote">

I think that is backwards. high silicone has a high expanding rate. not low... but </TD></TR></TABLE>
No, I got it right.

Bottom line; You may hear some noise when cold, and that's normal. But if the car is wormed up and you hear it, you may have a problem.

 

Bottom line; You may hear some noise when cold, and that's normal. But if the car is wormed up and you hear it, you may have a problem.[/QUOTE]

just what i was going to say

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by program &raquo;</TD></TR><TR><TD CLASS="quote">
No, I got it right.

Bottom line; You may hear some noise when cold, and that's normal. But if the car is wormed up and you hear it, you may have a problem.</TD></TR></TABLE>

I stand corrected. I got it backwards


Here is some info for you guys to read :
http://www.superstreetonline.c...23480/

Forging is a process that creates a solid chunk of uniformly grained metal. The details, features and sizes are then precision-machined from this piece to create a near jewel-like finished product. Forged pistons come from the aftermarket in various sizes, pin and ring locations, and dome configurations. Forged pistons signify a serious commitment to the engine’s performance potential; their ability to withstand heat and pressure at greater speeds inevitably means greater outputs than cast pistons. Most forged piston manufacturers offer two different alloys as the base material for the forged pistons. Forged pistons become stable at higher rpms, once their material expands, but can cause noise as they slap around in the cylinder walls at low speed when cold. The aluminum used for forged pistons differs in its proportion of silicone and copper, and thus offer different expansion rates. Additional silicone in a 4032 grade alloy yields a piston with lower heat expansion properties that maintains a tighter piston to wall clearance. Another grade of aluminum, 2618, contains less than one percent silicone with a higher content of copper. The composition of such pistons permit greater expandability and require greater piston-to-wall clearances, making it suited for the extreme heat and pressure caused by high-boost turbos, superchargers and loads of nitrous.