How to ID 3 liter pistons

[Tom Oxner]

I think the 3 liter engine came with 8.5, 9.3, and 9.8 compression ratios. How can I identify which pistons are which? Thanks for your help.

Tom

[tom1394racing]

Tom

There is a casting or forging number underneath the dome. Use this chart to match the number with the piston type.

[Tom Oxner]

Thank you very much for the information. That is what I needed to know.

Tom

[Walt Fricke]

Tom racing:

So the Euro and US 3.2 Mahles have the same casting? The US version just has what - more machining on its combustion surface to remove some metal and lower the CR?

This is of a distinct avocational interest to me, because at some point I can get my borescope up in there on an assembled engine through the oil return tubes. But if it is not worth trying on a 3,2 I won't. I'll have to rely on that the piston top looks like..

[tom1394racing]

Walt

This should help.....

Help - Identifying 3.2 Carrera Pistons

[Walt Fricke]

Oh, well. I can always just measure compression with the Whistler. I can tell if they are Mahle's with the borescope down the plug hole before checking CR to see which they are.

[Vin-barrett]

8.5 early 3.0 CIS is easy to tell because they are completely flat on one side
9.3 and 9.8 are similar looking in that 9.3 has a dip in the crown and 9.8 is flat

see here for the difference

are these euro pistons?

[Vin-barrett]

Here you go

[Walt Fricke]

Thanks, Vinny

Great pictures and captions.

Walt