Help Identify these 80mm pistons

[tom1394racing]

Can anyone identify these 80mm pistons?

They appear to be more aggressive than any of the 2.0 S pistons I've seen.

They look like the 906/910 racing pistons on page 140 in BA's book.

Can anyone help?

[cstreit]

They sure look similar 906 pistons to me... but I'm just a schlub, I'd wait for the experts to chime in.

[tom1394racing]

I wonder if they could be 69S pistons. The 67-68S motors are listed with a CR of 9.8:1, while the 69S is listed with a CR of 9.9:1

Here's another pic of a 2.0S piston. It is clearly different than the set I have. However, The difference between the two looks bigger than 0.1 CR points.

I know there is someone on this board who will know the answer.

[tadd]

Those are 906 pistons for the extra tasty 10.3:1. Are they in spec?

tadd

[DW SD]

Tom,
Cool find! What are you up to? Are you building another engine?
Your nosey friend,

Doug

[tom1394racing]

906 pistons...Wow!!!

I'll be offering these for sale in the classifieds along
with lots of her cool engine parts I recently purchased.

These have been inspected and are good to go. I wonder what they are worth?

[ErVikingo]

I can't really tell formt he pics but they look like 69 S pistons from here. Hopefully they are 906 though !

[tom1394racing]

Here's a pic of a set of 906 P's and C's I found by searching the forum.

They look just like the set I have. Does anyhave have a pic of a 69S piston?

I'd hate to sell mine as 906 pistons if they are really 69S.

Is there some way to tell them apart?

[tadd]

Tom:
You got 906 pistions. That peaked crown gives it away. Round that and you got S pistons. Then you loose valve pocket and you have E or L pistons, finally if you have little moonlets for valve clearence you are in T land. Simple as pie.

tadd

Edit: I think he was looking at the lower pic for that opinion...

[ajserrano]

Originally Posted by tom1394racing

Can anyone identify these 80mm pistons?

They appear to be more aggressive than any of the 2.0 S pistons I've seen.

They look like the 906/910 racing pistons on page 140 in BA's book.

Can anyone help?

Hi Tom! Hope all is well. While looking for a couple of used 906 pistons myself, I came across your old post here. The way to best identify your MAHLE pistons is by their casting number.

MAHLE 906 Piston = 80P24 and/or 80P24 W1

MAHLE 911S (69) Piston = 80P26 E

I included the 69S because most forum posts I come across are erronously describing the 69S pistons as "906" when in fact they are not.

If by chance you do have some 80mm pistons with the MAHLE 80P24 casting number, please let me know if those are available for sale, I'm interested.
I'm currently trying to complete one or two sets and need some 906 pistons that are within the same weight group. See below...

This is my current inventory of MAHLE 906 Pistons and Alloy Cylinders.



Now look at the bottom row, I have identified five 906 pistons that are very close within the same weight group, I need to be within one gram from each other (ideally). Less material can be removed from the steel wrist pin to get closer to a match, but removing aluminum from the piston itself takes a whole lot more milling for just one gram which can compromise the integrety and reliability of the component.



The 906 MAHLE Casting Number 80P24 variation...



another 906 piston, same casting number...



Below are some details for an OEM NOS set of 69' 911S MAHLE pistons, the ones that most often get misslabeled as 906. This is a bit frustrating when you see it all over the boards.



(photo courtesy of Phil Hindley, UK)





Now my used set of 69S' 80mm MAHLE pistons, same casting number as Phil's...



One-Year ONLY 1969 Porsche 911S / MAHLE Casting # 80P26 E



Hope this helps some... AJSERRANO at MSN dot COM

[tom1394racing]

Armando

I have a few of these pistons left. Email or PM me for more details

[ajserrano]

email sent. Thanks Tom!

[356RS]

Armando, Are these 80.94 the 81mm 906's?

[ajserrano]

Hi Mark! I just tried to call you...

Currently I have posted online a copy of the 1999 MAHLE Piston Casting Number Master List which is a later document and did not include the 906 variations, even the 907 which Phil and I suspect may be the very same part as the 906 pistons. Someone on this board probably has the earlier MAHLE Piston Casting Number Manual which could further shed light and answer some of our questions.

[Jon B]

All the cylinders shown in this thread appear to be Biral.

Original 906 cylinders were Chromal, with dimpled chrome-plated bores.
Porsche used Chromal cylinders for racing engines well into the 917 era.

[ajserrano]

Here is a very nice complete set of early 906 cylinders which I'm using on my 906 engine build.

I'm now looking for a comparably nice set of 906 pistons to fill these barrels. MAHLE p/n 80P24...

[ajserrano]

Technical Reference for 1968 on 911S...

Looking for similar document, but specifically for the MAHLE 906...



...photo courtesy Bernie Buschen...

[Flat6pac]

Years ago I did a pre A 1500cc with chrome linings on aluminum cylinders. Gorgeous factory material.
Bruce

[356RS]

Great information, Thanks Armando, Jon.

[blue72s]

Armando

So, apart from the casting number, what is the difference between the 69S and 906 pistons?

The domes look identical to me