Mahle Mystery Pistons - Calling all experts

I am trying to source a piston for an 85 308 QV, and I never dreamed that doing so would be so incredibly impossible. I see that Ferrari has two part numbers for replacement pistons used in these motors, one being a Borgo and the other a Mahle. The problem is that there appears to be two different versions of the Mahle piston that was used in the 3.0 QV. I have made a million phone calls & put this issue to some pretty knowledgable people, and nobody seems to know what's going on here. Every part number I have ordered has yeilded the "wrong" piston type and any help would be greatly appreciated.

If you look at the following photo:
Image Unavailable, Please Login
Notice the postion of the wrist pin is different, and the arc between the two skirts are a different shape. Both pistons have "8093" stamped on the top inside the dish. On the bottom, the "wrong type" is stamped with "81P9+" where the "right type" is stamped wtih "81P6+". Also, through exhaustive internet searching, I have located the following photo from a past ebay auction which shows the pistons I need and the box they came in, but did not specify a Ferrari Part nyumber.
Image Unavailable, Please Login
You can see the Mahle part number on the side of "2K 318 17" which seems to be an equally perplexing mystery to vendors. I would welcome any input on this problem, or if anyone has one of these pistons laying on the shelf, I would love to hear about it. Thanks In advance.

 

It appears to me that the piston on the left would probably be an early design piston and the one on the right would be a later design. I guess that by the skirt shape and the area under the oil ring. The piston on the right is also 20+ grams lighter I bet just by the shape, I'm guessing. I ran into a similar problem on F355 engines. The pistons in the engine had a slightly different shaped skirt, and the newer replacement pistons also weighed 19 grams more!! Further investigation by David at Ricambi showed that any pistons that didn't meet weight at the factory were sent out as replacement parts. As a result, we designed our own pistons-- better and lighter than factory pieces too, and cheaper. Depending upon how many pistons you need, you may have to resort to custom pistons too. In the Ferrari 180 degree flat plane crank, it is very important that all pistons weigh the same to keep the engine in balance. If you can't find a suitable replacement, PM me and I can give you a quote on custom pistons if you want.

 

ya know whats so funny, i have found out that many out of spec and downright wrong Lamborghini parts from the assembly line were boxed and shelved for "service parts".

now, 20 years later, when we are trying to keep our cars running, we find new old stock parts, that were garbage when they were new, and the supply of any good parts to be " 0 ". that explains why Lambo Jalpa wheel bearing are almost $700.00 EACH, and SKF and lambo "locked" the part number so you cannot get replacements.

lucky for me Diablo bearings with factory shims will work in a Jalpa.

so these small quaint Italian "craftsmen" did have a bit of Redneck in them after all.



LOL

 

I'm not clear on why one style is "right" and one is "wrong" as long as all 8 are the same.

Better than stock pistons are available from JE and others for less than OEM price.

The biggest reason for the scarceness of Jalpa parts is the small number of cars built (411) and they haven't developed much of a following.

Strut cartridges have been rare almost since the beginning.

 

If needing only a single piston or two, you may want to contact Dave Helms... he may have what you need too.

 

Simply stated, the "right" type is right because it would result in all 8 pistons being the same. Maybee I should have called it "the one I need".

This motor was rebuilt very recetnly and was again disassembled to investigate oil on one the spark plugs, even though the leakdown numbers were perfect. During the overhaul, the decision was made to reuse the stock pistons and replace only the rings simply because all of them, except one, were in excellent shape. I found a matching replacement piston at that time (by pure luck I guess), but it has turned out to be defective. There is a VERY small casting flaw which looked like a minor surface scratch, but examined under the microscope, revealed a <1mm fissure that went all the way through the piston. I wish to find a piston of this type because everything in this motor is in perfect shape except this one piston. I'm thinking that SOMEONE must have one of these somewhere sitting on the shelf somewhere in this world, but locating it is another thing.

Thanks so much for this lead. I will send him an email.

 

KEVIN ---

As with many out-sourced parts, you often get the supplier's (Mahle) id stamps and the end assembler's (Ferrari) stamps on the same part. Plus, with cast / forged parts, there are often id's for the "as cast / forged" version and id's for the final "machined" part --- this can be a source of confusion when trying to determine which part id to match to a replacement.

If you wish, send me a PM with as much "Mahle" info & identification stamps (plus everything else that's on the piston) as you can find, and I'll run it by a friend of mine who works for Mahle --- he may be able to hunt this down for you.

No promises though, as he works for the Filters Division of Mahle... but, he might know whom to contact internally.

 

Here are all the markings on the piston. I also sent you a PM, and I greatly appreciate your offer to look into this. Its things like this that make this community great!
Image Unavailable, Please Login
Image Unavailable, Please Login

 

This is my first post on this site. I got an Email yesterday from Williws telling me I need to join and check out this question. The 81P #s are the numbers of the forging. The 81 is for 81 mm diameter, the "P" is for forging (as opposed to an "L" for a casting or a "V" for a casting with steel struts), and the last digits are the "derivative" of that diameter. The "8093" is the last 4 digits of the finished print of the piston. What you don't know though is the change level difference if any. The numbers above the "M" tell you that this piston was machined at the MAHLE Rottweil plant (plant 5). The "04" is a MAHLE plant internal number that identifies which shift and/or which machine line. The "0184" says that it was machined in January of 1984. I think more importantly in this matter is the 2K31817. I am suspecting that this number is the first part of the drawing number. I will inquire to friends in Germany today to see if I can get prints that reference each forging type. Hang in there and don't stray to the dark side. Piston precision is toleranced tighter than parts in a Swiss watch.

 

What a small world.....

I was born in Rottweil, my mom was working as an administration secretary at the Mahle Plant.

Today my cousin is working at Mahle in Stuttgart (administration too). I gonna ask him if he can help.

Good luck, Till.

 

Sorry Kevin, no help here.

Dave

 

First of all, thanks for joining & providing such detailed and useful informaiton about the piston coding. Interesting and good to know. It then beggs the question to be asked...... If these were made on a manufacturing line in Germany, then why are they stamped "USA"? Does this refer to the piston as begin a "USA version" design?

With this info, I confirmed that the pistons I had labeled "wrong type" in the photo are indeed a later version or model. The stamp in the dish reads "506 / M / 0884" which, according to 288vol's decoding info, says that it was made in Aug 04 at the same plant in Rottweil. It is seeming that because the version I need is an older design, most stock has been depleated of that particular model. Even if someone has one of these older pistons, determining it is difficult becasue no new part number was issued for the revision change. Good thing these cars invoke such passion, because wtihout it, dealing with this stuff just wouldn't be tollerable.

I have come across some scattered mentioning about "Red Dot" and "Green Dot" pistons. Does anyone know what this is referring to? Weight maybee?

 

I'm sure it does refer to a USA version Ferrari engine application....great thread here!

308 engine pistons were all used up long ago in rebuilds of the 'oil burners' so we can use this Factory support!

Thanks again to those, joining in......

 

KEVIN ---

It looks like between "208vol" and "till", they've got you covered. So, I won't bother to ping my buddy at Mahle afterall.

 

there is a VW, (front wheel drive) that uses struts that fit the Jalpa.

ill be quiet and not distract from the thread.......

 

cool post, and welcome. its refreshing to see others help those in need, especially with parts for these crazy cars!

 

Kevin i "think" the USA spec cars were at a lower compression ratio and had a dished piston as opposed to the rest of world spec cars due to the emissions requirements. i could be mistaken, but it seems the "euro" cars of the same type, always have a higher compression ratio and require a higher fuel grade. then there are the camshaft profiles....

 

I think you might have heard this from me.

Not a perfect fit, I've modified a few sets though.

 

I just mailed all the information to my cousin at Mahle.

He told me that Ferrari-pistons are distributed in the so called "Motorsport"-department which is splitted from the normal aftermarket
That's why it is impossible to choose Ferrari as manufacturer if you visit: http://www.motorenteile.mahle.com/eLIZA/app/queryEngine

Now we have to wait for answers.............

Oh man, in 1984 I lived only 500 meters away from the place where this piston was made.
Today I live 500 m away from Mahle headquarter in Stuttgart.
There must be a solution.

Best, Till.

 

The times I have seen "red dot" and green dot" markings on pistons, it was to differentiate between bore clearances. For example an 81mm piston that actually measures 80.996 mm will be within tolerance, but require a smaller bore than an 81.004 piston, hence the red and green dots. That was not on Ferrari pistons, though, so take it for what it's worth. Also, I am picking numbers otut of the air; it's been a while, but I seem to rem pistons coming in 0.01 mm increments.

 

First information from my cousin at Mahle:

He transmitted the photos to the technical service. The competent engineer promised to look after our problem.

My cousin wont be in his office until wednesday 13th of march (skiing in Austria, lucky man). So don't worry if there are no news until then.

Best, Till

 

Well, first of all, I would like to thank everyone who made such an amazing effort in sharing your knowledge and helping me understand what I was dealing with in regards to my pistons. The definitive answer came from the last place I thought it might, which was my local Ferrari dealer. Ferrari of New England determined that my piston (aka: right type) was indeed an original design used in the QV motors, and Mahle improved the piston design late in 1984, yet no new part number was issued for the revision. There was at least one other slight revision after this as well. Here was his official response:

So, this piston that I have searched high and low for is now on its way, and thanks once again to all that helped. It is greatly appreciated!

 

That's great news - been a fun thread to follow and look forward to how this all turns out.

 

Adeptel, I still have more technical information on its way. I may be able to elaborate more after tomorrow. I am glad you have what you need on the way. As for til.a.fischer, you must live on Pragstrasse or Haldenstrasse. I was just there at the end of January, and I too had to make a trip to Davos / Klosters (Switzerland) for some snowboarding over the weekend. The motorsport part of MAHLE is located in Fellbach. There is also a motorsport division in the USA, but it is primarily focusing on Domestic (USA) racing - and quite successful I might add.

 

Adaptel,

great that the problem is solved.

208vol,

my office is indeed more in the center of Bad Cannstatt, that's the other side of the Neckar (river). But tomorrow we are moving....horrible mess, everything in boxes.
I didn't know that the Motorsport-part of Mahle is in Fellbach. My occupation is in architectur, my links to MAHLE are stricly familiar.

Am I correct assuming that you are working for MAHLE?
Davos is also a nice place to be. Growing up I spent some summers there.

I think we are all interested in more technical information on the topic.

Best, Till.