hosrom_951

The NA pistons were changed between early and late models, also the USA models are different than that of ROW models, you can tell by the design of the pistons, since the NA pistons have cut outs for the valves The CR ranged between 9.5:1 to 10.9:1 or so. Turbo pistons are 8.0:1 and have no cut outs like the NA as Michelle shown.

ehall

Thanks folks. That's what i needed. I saw a set for stupid cheap, and was lookingfor a way to decide the amount I was willing to pay for them. They sold for more than my level. Thanks all.

J Chen

But I remembered seeing Turbo pistons
with valve cut outs.

hosrom_951

ehall: I can get you a NEW set of 100.00mm pistons (tolerance group 1) for $660

Chen: Which ones?? i also cam across soemone who also mentioned seeing turbo pistons with valve cut-outs, you are the second person to mention that, but i never seen neither Mahle nor Kolbemschmit turbo pistons with such cut-outs, interesting though!

J Chen

BTW does anyone know the volume of the depression
of the 951 piston ?

Duke

Nah, those were probably from an engine with a broken t-belt

J Chen

Duke, Hos,
Firstly I think it was Danno who posted a picture
& I saw it on my buddy's 951 engine during
removal for a head job.

ehall

Michelle is showing her new pistons for her 951 build out above. They obviously have an indentation, as have ALL of those that I have ever seen. I just wanted to know if the NA's look the same?
Hos, If I only rebuild my stock powerplant, I won't need any pistons, I may still overbore to a 2.7 however. Whatcha got in 104mm?

Porsche-O-Phile

Talk to Hosrom - he's the resident piston guy.

ehall

"Talk to Hosrom - he's the resident piston guy."

lol You trying to get warmed up for the OT wars later in the day?

hosrom_951

Chen: I didn't say you were mistaken, i said that you are not the first person to say that they have seen 951 pistons with valve-cuts

ehall: 104mm?? sorry, i only have 104.51mm S2 and 968 pistons from Mahle

Porsche-O-Phile

LOL! No, just saying he's got an inside lead on cheap pistons or something out there in desert-land. I'm suprised he hasn't offered any yet. . .

Bill

Beyond the obvious differences in compression, the ring lands (area between the compression/oil rings) are thicker and the crown is thicker on the turbo pistons. Added durabilty against the stresses in a turbo motor (high heat, high combustion pressure).

If you look closely at Michelle JD's pistons, you will see the very thick ring lands.