Help identifying Pistons?
 

Hey all,
I have what we are told is a 3.0 motor
I have pulled the heads off and the pistons do not look like any reference pictures I can find.

head numbers 930.104.328.3R
cam number drivers side 930.105.147.9R

http://forums.pelicanparts.com/uploa...1477948711.jpg

http://forums.pelicanparts.com/uploa...1477948744.jpg

pulled out one of them.
I am going to guess JE just because that seems to be the most popular.
there are no numbers on it anywhere

http://forums.pelicanparts.com/uploa...1477953809.jpg

http://forums.pelicanparts.com/uploa...1477953831.jpg

still trying to figure this out
Thanks in advance

they look like JE pistons. those grooves on the top areContact reduction grooves. Contact Reduction Grooves: The
purpose of machining these grooves is
to reduce the amount of contact area
against the cylinder wall when the piston
“rocks over”. Contact reduction also
serves to disrupt the flame travel into
the crevice area thus helping to reduce
detonation.

Thanks for the reply Ken.
I am taking the top end off this motor for a re-ring and am debating what to do.
They are 95mm. Engine is a 3.0 as are the heads but the heads are the small ports.
We have 46 pmo's so I was thinking of just getting the heads opened up a bit and valve job but leaving the rest as is.

Your welcome they should have a build number laser etched on the bottom. Yeah I spent uber money on my heads but it's turbo with plans for a LOT of horse power.

I have looked for markings and have not been able to find any. I thought I read on JE site somewhere that prior to 2004 they didn't mark them.
I was mainly trying to figure out what compression rating they were with out having to CC everything out

you can probably just measure the dome height and they should be able to tell you.

good plan I will give them a call in a bit and report back

well thats interesting...the dome height on this piston is .348 and JE said their 9.5 ratio piston is .400 so this was either a custom or not from them

Those grooves i meantioned earlier are on thier custom pistons.

That is interesting. I wonder if they are just a really old set.
If so it was before they cast their JE logo in them.
When I spoke to them yesterday they said they will omit the logos on request but only 1% of customers opt for that.

My guess is they are from someone else and probably that someone orders sets at a time in their custom profile.

Just a quick google search for Contact Reduction Grooves and CP comes up first. didnt even think of them

I would suggest measuring the combustion chamber volume and the piston dome volume with a burette in order to determine your compression ratio. Even if you did have the specs from the piston maker, you can't be sure the head volume is spot on at 90cc (common number used for these heads)

Post a photo of the wrist pin clips. That might help to ID the piston.

Agreed KTL, I will be doing that when the motor is back together.
http://forums.pelicanparts.com/uploa...1478301884.jpg

how do these mains look to you guys?
http://forums.pelicanparts.com/uploa...1478301921.jpg

Those main bearings look quite good but hard to say without a closeup of each. The #1 thrust bearing on the left looks like it shows some "polishing" but that's not all that uncommon. I'm told it's a sign of slight misalignment of the bores. On an aluminum case it's not as concerning and i'd tend to think an align bore isn't needed. The magnesium cases are the one that get all out of whack and need an align bore of the mains to get them all in-line.

Thanks for the reply.
Case, rods, crank, oil pump, inter shaft, and heads are at the machine shop getting worked.

These are my JEs. 9.5 to 1 cr. Purchased a couple of months ago.
The pistons in this post looks on the top like the Mahles from a 2,7 RS with 8.5 to 1 cr.
http://forums.pelicanparts.com/uploa...1478663664.jpg
http://forums.pelicanparts.com/uploa...1478663756.jpg
http://forums.pelicanparts.com/uploa...1478663793.jpg

The pistons look more like an assymetric design and some idea of the pin offset would be interesting.

I think most Mahle pistons have a pin offset even if they are used the wrong way round on one side of the engine.

Mahle have, I believe, recently introduced assymetric pistons for the 997 and JE are doing something similar.

If they were Mahle they should have some forging numbers inside the crown.

They also look similar to RSR pistons.

Hey Chris I have looked over these pistons completely and have not found a single stamp, number, or any other sort of marking on them.
I can measure and post numbers tomorrow to see if that helps.
Took the cyls to the machinist and he said they are KS Alusils that have been lined and nickasiled

I must say it would be nice to get these ID'ed for myself and future people that may find some under their heads