Forged pistons

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MarkTurbo

Well-Known Member
I've done a few searches but a lot of the threads about forged pistons are 3 or 4 years old now.

What forged pistons are people using these days? The most common ones available seem to be Wiseco and CP's, are there any reasons to use one over the other? Obviously i want ones that clear the oil squirters. I'll be sticking with 86mm as my bores are virtually untouched so is it a case of just getting them honed to suit the clearances of the new pistons?

Its a shame my engine suffered a broken ringland on No1 as i wanted to push the standard pistons a bit more really :sad: But thats the risk you take, they could last a week or years!

For an engine that has done 135,000 miles and was running a fair bit of power all the pistons were in very good condition really.........apart from the bit that fell out :lol:



 
red reading

red reading

Active Member
Mark use cp's , just a light hone and they should drop straight in as they are made too out of the box, check the ring gap's though if they are a little bit on the larger side don't worry (turbo and nitrous engines run larger gaps than n/a anyway). all the tolerances come with the paper work in the box. also cp's dont rattle on start up like je's etc which is a good thing too.
 
fubar andy

fubar andy

Moderator & N/W Rep
Staff member
I've used JE pistons that were ordered from the US. They are specific for the RNN14 and have the oil squirter's milled out.

Some previous info on certain composition of pistons...just to add to my JE's don't rattle on cold start up, so go figure!

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4032 - is a low silicon piston. These are more for street applications. Low silicon pistons expand less and so can run tight clearances as with the likes of HKS. However the 4032 piston can become brittle under extreme stress and crack. If the 4032 starts to crack it continues and causes mass failiure.

2618 - is a zero silicon piston. There are more for higher power/pressure applications. Zero silicon pistons expand more and so require greater piston to wall clearance like the JE and CP for example. This can make them a little more noisy on cold start up. However they will handle greater pressures. In the unlikely case where a 2618 piston were to develop a crack it would lead to a lower point of stress and stop. The piston would still work fine..
 
M

MarkTurbo

Well-Known Member
Looks like CP's it is then. Danny if you remember i mentioned i was worried about a small amount of oil in No4 cylinder when we were at Dens a couple months ago, that turned out to be one of the valve stem oil seals but it was lucky i decided to strip the engine down anyway as there were no clues whatsoever that this ringland on No1 had broken.

samgtr said:
Were you running 1.7 bar on the standard internals ? Gt3071r?
Click to expand...
Yes, it lasted just over a year after bolting on the 3071.

fubar andy said:
just to add to my JE's don't rattle on cold start up, so go figure!
Click to expand...
Andy, i built a gearbox for somebody that had JE's a few years ago and his engine wasn't noisy when cold either, maybe its another one of those myths like standard pistons won't take more than 1 bar :lol:
 
red reading

red reading

Active Member
It's not just the material they are made of, belive it or not race pistons are not round when measure'd at the engineering standard temp of 20oC, they only become round when at the correct running temp. hence why very highly tuned (specifically F1) have to pre heat the block and oil so that when they first start the clearences are near to correct.

Cp pistons are made by carillo and lets face it there conrods are some of the best in the world so why would there pistons be anything less?!
 
A

ashills

Active Member
The CP's are very good and the hks have the offset pin to keep them quiet i think the wiesco's are aswell but tbh all the big name's make a good piston now, think the wiescos are used alot on stock size drop ins on the evos and run nice and quiet
 
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