MyE28.com

Hi,
I am trying to find pistons for my M30B35 engine from my Euro spec E28 1987 M535i.
I need some oversize pistons but I can't find any Meyle or KB origionals.
The origional pistons were pt no: 11251276701
The first oversize pt no: 11251276703
The second oversize pt no: 11251276710
As far as my research goes they are all NLA.
Has anyone ordered some custom pistons from anywhere to suit a 92.25 to 92.5mm bore?
If so where did you get them made?


Thanks

It is not easy at all to find stock oversized pistons for the Euro E28 535i M30B34 engine. Note that the piston in the picture you've posted is not for the E28 M30B34 engine, but for the E34 / E32 M30B35 engine. The correct piston for the Euro spec (10:1 compression) E28 has a piano-shaped top.

You may want to try Hubauer Shop in Germany, maybe you're lucky to still find them brand new:
https://www.hubauer-shop.de/en/
Before that, you may want to carefully double check the part numbers and make sure you're looking for the right piston. Realeom is very useful:
https://www.realoem.com/bmw/enUS/select

As a side note, you may use also the E34/E32 pistons, whose tops look like in the picture you posted. Despite that they yield a compression ratio of 9.0:1 in M30B35, when mated with the E28 M30 cylinder head they will get you around 9.8:1 compression. This is due to the fact that M30B34 combustion chamber volume is smaller than M30B35. Factor in the overbore, and you'll be very close to 10:1.
To make things even more complicated, note that there was also a super are 9.1:1 compression piston, unsed in the non-cat version of the Euro E32 735i and very late E24 635CSi. See the picture at the link below:
https://www.magicview.ro/mye28/pics/M30B35_pistons.jpg

For second-hand pistons, you may want to check:
https://www.kleinanzeigen.de/
As of now, there are several offers for used M30B35 (read E32/E34) "0" size pistons, none for M30B34 (= E28) Euro pistons, but one for "+25" (92.23mm) size M30B35 (= E32/E34) brand new Mahle pistons. Make sure you're seated before you read the price:
https://www.kleinanzeigen.de/s-anzeige/ ... 5-223-1857

Good luck!

Thanks so much for all of that information.
I am finding it very hard to work out what I have as RealOem states I should have pistons pt no: 11251276701
Yes this is a M30B34 engine produced in 4/87 so quite a late version of this car bought into the UK.
I am very confused though as the bore is definitely standard but the pistons do look like those out of a later E34 B35 engine as shown in the following picture https://photos.app.goo.gl/UCsJpq82z8tGEwD26
The pistons are 92mm which is the standard size and I am fairly sure these were the original pistons
The number on the block matches the VIN.
I also took a picture of the combustion chamber https://photos.app.goo.gl/oe3D4ttEawQmVPxh6

The pistons look like they have a very minimal dome on them.
I am really confused as to which pistons I need now?
Ideally I would buy some to increase the compression if it is low...

I also measured the intake valves and they are 47mm

I'm a little confused...my understanding was an M30B34 would have either flat top (low compression) or piano top (high compression) pistons. Here's a picture of a piano top piston, so named because the raised portion looks kind of like a grand piano:



Here's an older discussion that shows examples of M30B35 pistons: https://www.mye28.com/viewtopic.php?t=144340