Vilhuer

.125 is half of the number normally quoted and I think even that can cause problems. 104mm is at upper limit of most blocks even without core shift.

John Veninger

This is excellent news. So what is the engine size using 103 pistons with the standard stroker crank?

Anyone know the current price on stock 968 pistons?

Vilhuer

103.00mm x 95.25mm = 6.35L/387cid.

$540 or 474.07 euros each in few places. If they even are available new.

dprantl

Aren't 968 pistons the same as 944S2 pistons? Not that they would be any less rare, but at that ridiculous price you could probably source a banged up 944S2 and use its pistons.

Dan
'91 928GT S/C 475hp/460lb.ft

John Veninger

Yes, 944S2 are the same. all depends who made them.

Typical rate for used ones are around $100-$200 each, and they are USED.

$1700 for pistons that run in the original bore material is a good way to go.

I just hope I don't have to use that option anytime soon!

Vilhuer

Most 944 S2 seem to use Mahles which do not work in 928 stroker as they have full skirt while most 968 have Kolbenschmidt which work. Finding 8 good condition pistons can take years unless one buys few 968 engines. Which might not be too crazy way to get them. Selling block, crank, heads and cams might net so much $$$$ that pistons can end up being practically free. That is still slow and less smart way than geting new and very likely much lighter set for under $2k. In the end large part of the money can be saved on possibility to use cheaper heavier rods and need for less added mallory to crank.

atb

Russ are you sure about this? I don't have a cite for you, but I'm pretty sure that the Reynolds minimum spec was .250" wall thickness. I'll see if I can find a source for my number, do you have one for yours?

This issue with going slightly larger than 104mm is finding a ring that will work with the alusil at that bore size, no one makes one.

-Adam

atb

Yeah, what Erkka said....

Mark Anderson

No they are not the same. I have used both with good sucess but the S2 pistons can require some clearance. I do have some good used S2 pistons for $50 ea.

Fabio421

Ring that will work with the Alusil? The rings aren't special, are they?

ddarnell

Are the Wossners forged? Never mind I read the title
David

Vilhuer

Oh yes they are.

That ring sizes are available? BMW's Alusil engines all have under 100mm pistons AFAIK so no help from there.

Chris White

BTW - the 106.5mm pistons I mentioned were for a 951 Darton MID sleeved block...
I hope nobody thought it was for a 928 block!

Chris White

Wossner does have alusil rings availalbe up to 106mm, I had to pester them for almost a year to get them up to that size.

martin D

Ring material for Alusil.
What will / wont work or best options ?.