Help Identifying This Piston

[echrisconnor]

I'm trying to put new pistons in the Nickasil cylinders in my 3.0 engine. I just got the following pistons used, however it appears that they're Klobenschmidt (sp?) ones for Alusil jugs. Can anyone confirm this for me and whether, in fact, they are unuseable. You can clearly see the KS marking on the inside.

[KobaltBlau]

They look like they have the iron coating used with the alusil. Kolbenschmidt did make some nikasil p/c combinations, but I bet your suspicion is correct.

BTW, are you starting work in earnest?

[Henry Schmidt]

Chris, your pistons are iron coated, cast pistons used in Alusil cylinder.
One easy way to tell cast from forged is that forged pistons never have full circle skirts. The reason is that forged pistons expand too much. Here's what a forged Nikasil piston looks like.

[smestas]

I'm no piston expert but it looks just like the KS Alusil pistons that I used in my rebuild.

[KobaltBlau]

Same number even on simon's, looks like.

Chris, looks like you have unmatched Ps and Cs.

[smestas]

From some of my other pics it looks like the number on the other side of the KS logo is 095136

[echrisconnor]

Yup, that's what I was afraid of. Damn. Thanks to all for the feedback.

Anyone know of a good source for another used set of 95mm 9.3 or 9.8:1 Mahle pistons for Nickasil?

[Henry Schmidt]

Originally posted by echrisconnor
Anyone know of a good source for another used set of 95mm 9.3 or 9.8:1 Mahle pistons for Nickasil?

I might have a set. I'll check and get back to you. As you can see we have a large inventory of good used Ps & Cs. What size group are your cylinders?

[echrisconnor]

Henry -- thanks for the offer: looks like you're swimming in pistons. It also appears that you responded just as I was editing my post changing "cylinders" to "pistons." Anyway, how do I look for the size group on the cylinders? I just knew I needed to spec 95mm Mahles.

Thanks,

Chris

[Henry Schmidt]

Here's a quick lesson on piston and cylinder identification.
Cylinders are either Nikasil or Alusil. Kolbenschmid or Mahle.
The easy way to tell Alusil from Nikasil is that Nikasil is magnetic. The size is bore diameter ( 80, 84, 90 and so on) plus a size designation. This number is on the cylinder near the base gasket. It is a 0, 1, 2, 3. Be careful not to mistake a mechanics numbering system for the size. All cylinders in a set should be the same. Next there is a triangle with a number in it. Either a 5 or a 6. This is the height group. These must also match. When building a race engine we always measure and trim ( if necassary) the cylinders because we are looking for a tolerance closer than Porsche.
Next the piston:
The piston is marked with a diameter number also. 0, 1, 2, 3. When new, the piston should match the cylinder. As pistons and cylinders wear it is nice to put larger pistons in smaller cylinders. For example 1 piston in a 0 cylinder.
Pistons also have a weight group marking. This can look like - - , - , nothing , +, ++ . These marks correspond to a designated weight. These weight groups can be found in factory spec books

[echrisconnor]

Henry - great reply. I've been looking for some sort of decription like this for a long time. Is there any way of determining what the stock or intended CR of the piston is - such that you could tell the differnce between a 95mm 9.8:1 piston vs 8.5:1 other than looking at the dome shape?

[echrisconnor]

I know this isn't the Parts Classifieds, but I thought I might get some help here:

I'm at the final stage of my engie rebuild and am trying to source some good, used pistons. What I'm looking for is a set of six, good, affordable, used 9.3:1 95mm Mahle Pistons for Nickasil cylinders. These are going into a CIS 3.0 engine.

I need some from a later SC that are still in good shape. Please shoot me an e-mail at:

echrisconnor@yahoo.com

If you have any, or know of a good source I might call.

Thanks to all.

Chris Connor