Just wondering if anyone else out there has installed some Manley pistons in their set-up? I did in my build and I am being told the noise I can't get rid of is piston slap. This sounds horrible especially for a new motor. I'm just wondering if anyone else is having this issue?

 

Video of said sound

 

I can't really get a good video of it because it doesn't really do it at idle so when driving the turbo and wind noise overtakes it on the camera mic. I am going to try and borrow a friends go pro that should be able to get it pretty good.

 

Is the noise rpm dependant? Does it get quieter when the motor warms up?

 

It doesn't really seem to get much quieter when it warms up and yeah it is kinda rpm dependent beings the noise is not there at idle and is not as noticeable at higher load and rpm

 

What did you set the ptw clearance to?

 

Unfortunately I trusted the machine shop and did not double check so I am not sure what they set it at I do know that with the head off you can rock the pistons back and forth in the cylinder. When I ask them about it they said it was normal. Seemed excessive to me.

 

It is normal.
I used 86mm pistons and bored the cylinders to 86mm.
you can't get an accurate piston to wall clearance with Mahles because they have the skirt coating on them which is not a consistant thickness.
If your machine shop installed them at 0.003" clearance, it will more like 0.004"-0.0045" which is a lot for 4032 alloy pistons.

Cheers, Mike

 

I think it definitely has to do with your PTW clearance. However, pistons with more silicone coating are less prone to piston slap.

JEs use no coating, and although they are an extremely strong piston, this makes them slap happy.

Due to the fact that your pistons are coated, unless gapped loose, I don't know if I'd expect them to be as loud as you're describing.

 

the noise definitely gets quieter after the car warms up. I am thinking the machine shop over bored the block a bit :/

 

The looser the gap, the louder the slap! So isn't what you're doing going to make it worse?

 

what oil are you using? thicker oil can cause this to happen on start up

 

I'm not understanding you what am I doing that would make it worse?

and i was running 10w 30 then threw 20w 50 in to see if it would help. it does it with both.