Doing research on a 383 build and I have been leaning toward hyper pistons because of the quieter operation and better wear characteristics. This engine will be fairly mild with a hot cam and bowl ported stock heads but I wonder if I might get the itch to put nitrous on it later on.
From what I've been able to pick up so far SRP makes forgings from two different alloys and the 4032 alloy can be run as tight as .0035" clearance in mild nitrous applications. I think Probe makes something like this too. Any input on which forged pistons have the least expansion and can run the closest piston to cylinder clearance would be appreciated.
Thanks, Michael

 

my diamond forged are .004" clearance. no slap whatsoever, even in 50* weather. this winter will let me know if it slaps in the dead cold

 

Probe can get ya fixed up.
.004 will NOT cause a piston to slap. It's when the shop screws up and puts in too much clearance.

 

Mahle - with the coated skirts and the same 4032. The coating is about .0005" thick per side, and is ignored when setting up piston to wall...in effect this makes the clearance tighter, but the coating makes this ok.

Really forged pistons shouldn't rattle thse days even without the coatings. The short skirt on a 383 piston will make it more prone to rattling though.

 

I really have not had good experiances with probe, every single time their pistons are horribly weight matched and I have to remove metal to set it straight. The only time I use them is with cheapo 460 stroker motors where the customer doesnt want to pay for some nice JE's.

 

I went with .0065 on my piston to wall clearence in preperation for a big shot, and possible n2o and boost in the future once i get the compression down. That was as per JE pistons tech who almost fliped when we were about to do .0035 when we told him what we were planing on doing, hehehe. Good thing we called

 

Hey, ya got to balance it anyway. Maybe they do special for me but I haven't had that problem but most I get are not off the shelf.

 

I didn't have any problems with my pistons either Probe must have done them special for me too

 

We run Diamonds in most everything we do, and I have run as close as .004 and as loose as .0065 for big power adder stuff. I've never seen piston slapping or rocking around in the bore, but then again a little coating goes a long way.