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Need help Identifying Mahle aftermarket RSR looking piston on a 3.2?

ive moved this inquiry from the tech section since i didnt get much responds....help please!

Hello fellow pelicaners

Im looking to replace this piston but im not sure what it is? It looks like a 98mm 3.0 RSR Motorsport piston but my motor is a 3.2? from what I understand 3.0 and 3.2 piston arent interchangeable.

Did Mahle make a version of this piston for the 3.2s. the new recently released (not MMortiz) Mahle P&Cs are different looking than mine which are probably an update.

Any mahle experts here to help decode these numbers?

Markings on the top:

Tiny M mark numbers are hard to see. I think they are 552 on top 0987 on the bottom of the M

Then 94,95 (mechanic measured pistons and its bigger from the bottom of the oil control ring chamfer all the way to skirt area. Is this normal?)

Followed by 39/7

Markings on underside of the piston:

95P30 W2.

Anyone have any experience with i knows where I may be able to find these pistons?

regards pf




Old 06-21-2016, 03:08 AM
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It's a 914 ...
 
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To be clear, your 3.2L motor is a 70.4 x 98 or a 74.4 x 95?
Old 06-21-2016, 04:09 AM
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Puny Bird
 
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3.0 and 3.2 is the same size piston bore (different pin on the piston), the crank stroke is longer on the 3.2.

Those are high(er) compression pistons, but I don't know if those are "RSR" as mine are an RSR style 95mm and are more of a peak shape.
That said Mahle made all kinds of different piston dome shapes, Mahle had some on the shelf performance pistons, but if you had the budget they would make you any dome you liked.
Unfortunately matching them up will be a crapshoot.

I say mine are RSR "style" because they are 10:1CR with regular heads. I don't know the history but they were obviously from a custom run.
Unless you have real 3.0 RSR heads you don't want real RSR pistons. RSR pistons in regular heads will have close to the same CR as USA CIS pistons.

The narrow on top, wider on the skirt is normal.
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Last edited by Mark Henry; 06-21-2016 at 07:26 AM..
Old 06-21-2016, 07:21 AM
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WTB one Mahle 95mm Racing Piston (can anyone ID for me)

It looks as in 95P30W2 is a forging number and was used for several different crown styles.
Old 06-21-2016, 08:08 AM
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Quote:
Originally Posted by stownsen914 View Post
To be clear, your 3.2L motor is a 70.4 x 98 or a 74.4 x 95?
standard 3.2 95x74.4 i believe

Quote:
Originally Posted by Mark Henry View Post
3.0 and 3.2 is the same size piston bore (different pin on the piston), the crank stroke is longer on the 3.2.

Those are high(er) compression pistons, but I don't know if those are "RSR" as mine are an RSR style 95mm and are more of a peak shape.
That said Mahle made all kinds of different piston dome shapes, Mahle had some on the shelf performance pistons, but if you had the budget they would make you any dome you liked.
Unfortunately matching them up will be a crapshoot.

I say mine are RSR "style" because they are 10:1CR with regular heads. I don't know the history but they were obviously from a custom run.
Unless you have real 3.0 RSR heads you don't want real RSR pistons. RSR pistons in regular heads will have close to the same CR as USA CIS pistons.

The narrow on top, wider on the skirt is normal.
I'm running 3.2 twin plug heads

yes the domes arent as tall as a real RSR. u can see the valve relief cut outs arent as pronounce.

so the piston is suppose to be smaller in diameter from the oil control ring up hence the 95/94 markings?

too me the piston looks in great shape, no pocking, detonation marks or scuffing on the skirts. the other pistons 5 cyclinder leaked down at 1-2% so the motor is tight with no leaks. this number 6 leaked piston was down at 16%.

what is strange that the 2 compression rings look to have excessive gap and they were lined up on top of each other?

cylinder look good to and it measure out fine and still had honing crosshatching. could it just be the rings that had the gaps lined up together?

i may send the piston and cylinder out to someone that has precise measuring rig to see if they spec out and have it CC'd. can u do that with any sort of accuracy with out it assemble to the block and crank?

Quote:
Originally Posted by chris_seven View Post
WTB one Mahle 95mm Racing Piston (can anyone ID for me)

It looks as in 95P30W2 is a forging number and was used for several different crown styles.
yes same number but not only my dome is more shallow but the buttom of the piston mine had a skived out area on the shelf area which the pic in the link dont have.

I also don't have the "tabs" on the skirts like most rsr pistons

perplexed...

Last edited by panzerfaust; 06-21-2016 at 10:43 AM..
Old 06-21-2016, 10:28 AM
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Pics from the link for reference..


Old 06-21-2016, 10:45 AM
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Puny Bird
 
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My pistons, which were new in the box, were a hair undersize. We're not sure why, but most likely the reason they were never used. I had to have my cylinders re-plated and sized to fit.
I assume the piston is undersize on top as that is where the heat/expansion would be, all aircooled pistons seem to be built this way.

I would definitely spec it out, check the ring groves for wear and make sure you have the correct CR for you app.
If they do spec out good, even if you have to re-plate your cylinders to fit the pistons, it will still be a cheap set of Mahles. My set with the re-plated cylinders would be worth close to $5K.
I would send them to someone like CE or LN to check them out. If all is good I'd also get the skirts DFL coated.
Finish it off with a new set of goetze rings and you're back in business.
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'74 Porsche 914, 3.0/6
'67 Bug, 2600cc T4
'67 Bus, 2.0 T1
Not putting miles on your car is like not having sex with your girlfriend, so she'll be more desirable to her next boyfriend.
Old 06-21-2016, 11:02 AM
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Puny Bird
 
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Those look like my pistons
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'67 Bug, 2600cc T4
'67 Bus, 2.0 T1
Not putting miles on your car is like not having sex with your girlfriend, so she'll be more desirable to her next boyfriend.
Old 06-21-2016, 11:05 AM
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Piston being narrower on the top than skirts area is the reason mahle cylinder is tapered? Perhaps my cylinder has been replated or rebored without this taper?

Do CE or LN do mahle work? I thought LN makes there own slugs n jugs? I'm thinking of getting a new mahle tapered cylinder and reusing these Pistons.
Old 06-21-2016, 12:25 PM
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Puny Bird
 
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Quote:
Originally Posted by panzerfaust View Post
Piston being narrower on the top than skirts area is the reason mahle cylinder is tapered? Perhaps my cylinder has been replated or rebored without this taper?

Do CE or LN do mahle work? I thought LN makes there own slugs n jugs? I'm thinking of getting a new mahle tapered cylinder and reusing these Pistons.
Pretty sure cylinders are not tapered, if it is it's likely out of spec.
My cylinders had what looked like good crosshatch but were out of stock spec.

LN (Millennium IIRC) did my mahle cylinders, but Charles is an old friend of mine.
__________________
'74 Porsche 914, 3.0/6
'67 Bug, 2600cc T4
'67 Bus, 2.0 T1
Not putting miles on your car is like not having sex with your girlfriend, so she'll be more desirable to her next boyfriend.
Old 06-21-2016, 12:38 PM
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ok thanks i will give them a ring..
Old 06-21-2016, 01:08 PM
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