Mahle Alusil or Nikasil

[classictarga]

Hi everybody,

I got a little problem with the identification of a cylinder. The engine comes of a 1977 911 with CIS (165HP). Some head studs got loose ans smashes 1 cylinder pretty bad. Now Iwant to get a new cylinder and I'm not sure what I got:






Cylinder and piston are both Mahle.
The casting # of the piston are "CO21" , "90L61" .On top of it it says "A2"
The casting # of the cylinder is "90ZN2 W6"

Almost all those Mahles are supposed to be Nikasil cylinders. That "almost" is my problem: The inner surface of the cylinder is not magnetic, so that should be Alusil.

I read a hundred threads about identifing those cylinders and I did not get any further.

Can anybody tell me by checking the pictures and the casting numbers what I got?

Thanks for your help,

Nico

[Flat6pac]

The easiest test is with a magnet.
The Nikisil will draw a magnet slightly.
Thats always my first test so I know what Im working with for sure
Bruce

[cnavarro]

I would say it looks like an alusil.

[tom1394racing]

Those are Mahle Alusil.

I can provide in-spec replacements for both the pistons and the cylinders.

PM me with your email if interested.

[classictarga]

Hi folks,

thank you for the quick replies. I also thought it had to be Mahle Alusil, but since they are so rare, I did not want to believe, that I acutally have 2 Mahle Alusil engines at once. Al least I can start to swap parts.

Thanks again for your help,

Nico