I have srp 8.5:1 pistons in my b18b and there is really bad piston slap, and the guy that is working on it said that it is normal for forged pistons to have alittle piston slap. But this is making so much noise, i know that it is now normal at all and he is just trying to get around fixing it. He said when the motor heats up it should go away, sometimes it does and sometimes it doesent. So does anyone else have this problem with their forged pistons, especially srp forged pistons. I think im going to pull the motor out order new pistons and rings, then have a machine shop put it all together so i know that all the measurements are right.

 

Nature of the beast for forged pistons with LOW silicon content but SRPs have a high silicon content and they expand less when heated up so the piston to wall tolerances should be pretty tight and not have alot if any piston slap. Arias, Wiseco and JE have a very low silicon content so they slap alittle but not bad, well I have never heard the Arias but people say they are loud. I hope the guy didn't put too much clearance in there, Imports and Honda's especially run tight tolerances, hopefully he wasn't some domestic head using loose specs. Did it always slap bad from the beginning or is ot getting worse?

 

if it doesn't get quieter when the car warms up, your probably going to have problems sooner than later.

 

the guy that did it normally works on domestics, but he was a friend of my dads, so i had him do it. Its always had alot of slap since the forged pistons have been in, which has been about a month. If it were u would u have it torn apart again and new pistons with a tighter clearence put in???

 

YES! From what I know about SRP is that they are High silicone content so they don't expand as much as the regular JE with low silicon content. From what I've seen on friends cars with SRP is there is little to no piston slap. If it did it from the beginning I would be suspicious, possibly too loose of a bore. Are you sure it is piston slap and not valves or possibly rod knock? New injectors? Sometimes injectors can be loud too, just throwing stuff out.

 

i had 9:1 SRP pistons before on my first rebuild and YES i had big time piston slap!! my mechanic also took a look at them and told me they were in spec as well. i just couldn't figure out why i was getting so much piston slapping noise even when the motor was hot. so to make a long story short, i got sick of the noise, bought some ross pistons, installed those and now i'm living a happy life!!

 

I run Arias9:1, I've got slap that won't go away, been like that for over 10,000 miles, beat the hell out of it, spray the hell out of it, yeah I hate it but it's still together.

 

that is strange.. I used JE's and I was worried about slap noise when I got them, but I never had any at all

 

I was thinking that it could be valve train noise too, so i had the valves adjusted and they said that the rockers were loose, but now everything is tight and the noise is just as bad as it was before.

 

I have pretty bad piston Slap. I have JE 9:1. The slap wasn't as bad when i first got them put in and now they are getting worse. What does that mean?

 

I talked to the guy that put it together and he told me that the reason why its doing it is because the pistons are turbo pistons, and they have a greater clearance for a reason. He said that they are designed for racing and that my motor doesent get hot enough under daily driving conditions for the pistons to expand all the way, but if i were to run my motor hard under boost that it wouldnt make the noise. Sounds pretty logical to me so im going to take is word for it and put in 20w50 racing oil and hope that this helps it alittle. what do you guys think??

 

logical, but partially incorrect.. what everyone told you in the previous posts is that the srps have high silicon content i.e. dont need the room to expand that you engine builder has left for them..

on a street engine "where it doesnt get hot enough for the pistons to expand to the proper clearance" your motor will not last long