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How to ID 3 liter pistons

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
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#19 Spec Boxster, 1972 911T (with 3.2), 1985 930-EFI Conversion (in progress), 2002 Turbo X-50
Old 08-13-2012, 08:46 PM
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Tom

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

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Old 08-14-2012, 02:35 AM
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Thank you very much for the information. That is what I needed to know.

Tom
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#19 Spec Boxster, 1972 911T (with 3.2), 1985 930-EFI Conversion (in progress), 2002 Turbo X-50
Old 08-14-2012, 05:41 AM
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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..
Old 08-14-2012, 06:31 PM
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Walt

This should help.....

Help - Identifying 3.2 Carrera Pistons
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Old 08-14-2012, 06:42 PM
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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.
Old 08-14-2012, 11:06 PM
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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?
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Old 08-17-2012, 09:52 AM
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Found pics

Here you go



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Old 08-17-2012, 10:01 AM
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Thanks, Vinny

Great pictures and captions.

Walt
Old 08-17-2012, 12:43 PM
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Old 08-17-2012, 12:43 PM
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