Visual and Spec Differences for Pistons - 67/68S, 69S, 906

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Originally Posted by blue72s

Some pics of 81mm pistons (not mine)

http://www.early911sregistry.org/for...1&d=1322152431

http://www.early911sregistry.org/for...1&d=1322152954

http://www.early911sregistry.org/for...1&d=1322152509

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Here's the thread with those pics. It looks like they are identitfied by 80P26 which matches with the chart in the first post of this thread. They also appear to be 3 ring, not the oversized 2 ring pointed out in the chart.
The mystery continues.
http://www.early911sregistry.org/for...le-906-pistons

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Here's a set of pistons claimed to be 906. But I am thinking they are (were) 69S instead, based on the lack of holes drilled above the wrist pin boss.

Again, it's still not clear what the real differences are between 69S and 906 3 ring pistons, so I hope someone chimes in with an answer...

http://www.early911sregistry.org/for...FS-906-Pistons

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Here's a difference I am beginning to notice as consistent. It shows up between the 67/68/69S and 906 pistons labeled as such in the archives:

'S'
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906
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You all need to provide dome height and dome volume numbers so you can compare pistons. I have two 906/911R sets here, one used 80mm #80P24 W1. Dome height is 17mm and the dome volume is 36.2cc. the second set is new 81mm #80P26 + E. Done height is 17mm and dome volume is 37.2cc. Both sets have the drilled underside and look like pistons in post #11. Gordon

there are 80.5 mm 67-68S and 906 3 ring pistons. My early 80.5mm 906 piston doesnt have the drilled holes.

A visual reference to NOS 67-68 p & c here:

http://www.early911sregistry.org/for...-and-cylinders

A set of refurbished and measured 67-68S pistons here. Note 80P26 for 67-68S.
http://www.early911sregistry.org/for...-and-Cylinders

I think chart in my first post is so ridiculously off base for determining piston application, or this number has nothing to do with a certain piston type and more to do with manufacturing process.

Experts please weigh in

Very intersant......

Another recent thread:
http://www.early911sregistry.org/for...-Mahle-Pistons

And more great reference pics for NOS 69S pistons:
80P26E

http://www.pbase.com/9146gt/my9146gt...80p26e_phil_uk

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Another set of 69S Pistons
80P26E

http://www.pbase.com/9146gt/my9146gt...80p26e_lorimer

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