924Board.org

[morghen]

I have three of these puppies..they look useable..but i have to measure them.
The 4th one is FUBAR..probably timing belt snapped as the three still in one piece pistons have valve marks on them
I have to measure the block too..especially that 4th cyl...it looks like it has some aluminium deposits on it but no damage is visible.

I dug a bit about pistons and its strange that the writing on the pistons say 86.95
I was thinking to measure all and if they are right, to look for a replacement piston and use them to rebuild the spare engine.
However...these look like S1 pistons and i think CR would be 8:1 ?





Some more pics of one of the pistons:






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Supercharger and EFI kits
https://www.the924.com

[Carrera RSR]

I have a set of S1 86.95mm pistons in a spare block which needs rebuilding as it lunched a big end bearing, rod and crank. Just need to swap them in to another block I have with 86mm pistons which bores are now out of tolerance to be reused. But the crank and rods are still good. I will rebuild as a stock full spare engine, crate up and store away for a day when all turbo parts are NLA.

The S1 RoW pistons run 7.5:1 CR not 8.0.
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1980 931 - forged pistons, Piper cam, K27/26 3257 6.10 hybrid turbo, 951 FMIC, custom intake, Mittelmotor dizzy & cam pulley, H&S exhaust, GAZ Gold, Fuch'ed, Quaife
Now www.924board.org/viewtopic.php?t=34690
Then www.924board.org/viewtopic.php?t=31252

[morghen]

meh...they are no good to me then.
i need a set of S2 pistons...

Perhaps its worth looking for a 4th piston to complete the set...
_________________
Supercharger and EFI kits
https://www.the924.com

[Raceboy]

I have almost brand new 86.95 931 S1 piston.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[morghen]

You have just one ? will you sell it? i have to measure these first to be sure they are fit for usage.
_________________
Supercharger and EFI kits
https://www.the924.com

[Raceboy]

Had four from blown 931 engine I bought several years ago, with one (4th) being toasted by detonation, two others had minor damage and one is in very good condition. These pistons were in the engine for maximum few thousand km's.
BTW, all had broken rings which were also new when engine was assembled.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

[WEASEL149]

If you use the 86.95mm OEM pistons, change the top compression rings for Total Seal ones. Doesn't matter whether they're gapless or not.

Oversize OEM rings that I have examined have been cast iron and as a result are crap in a turbo engine and will break if you look at them with the wrong expression
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1979 UK 932