951and944S

Yeah I contacted Andial about those but they wouldn't say if the 8V piston could be modified for 16V use. I'd love to see a high quality picture of the piston face but I can't imagine that you'd have valve/piston conflict with the 16V head with such a low compression piston. Does anyone know if the Mahle 3.0 liter 8V turbo piston has reliefs...?

Here's what Andial said- "Hello Terry,
The piston is only for the 8 valve head and we have no future plans to have a 16 valve version made. Honestly I'm not sure if the piston could be modified to accept the 4 valve positions on the head and still keep the same compression ratio.
Regards,
Pete Sanchez "

Terry S.

RajDatta

The stock 16 valve pistons have valve relief for intake and exhaust. The 3.0 2 valve pistons have neither. That is the biggest issue with making the 8 valve pistons work on a 16 valve head.
The compression is lowered partly due to the combustion chamber design on the 2 valve head and also the center area of the piston is dished quite deeply just like the standard 951 piston.
Regards.
Raj

951and944S

Raj thanks , that's what I figured. Been inside a few 944S 2.5's and I have a complete 968 engine so I've seen the reliefs. You brought up an interesting point though that probably answers my question. The new 8V Mahle 3.0 piston isn't really that dramatically different since most of the compression relief is gained by adding the 2V head style combustion chamber. Since the reliefs are pretty deeply cut in the stock high compression piston I assume Mahle was fairly confident of the strength of the remaining material spanning the piston face. I don't see why the factory pistons couldn't be machined down that far and retain the same integrity.

Ah, I'm still considering options, I may sell the 968 head, pistons and cams and buy the new Mahles and a 2.7 head.....

BTW-Took a look at your "pics of my car" thread.......was at a loss for words then and errrr....well I still am....

Terry S.

RajDatta

Terry, thank you . Its been a work in progress and there is still plenty to do. Its all in parts right now. I would go with the 8 valve option as its a proven method and that is how Porsche did it as well. The sales of your items should help fund the swap.
Raj

Under Pressure Performance

For those interested. We have the last set of Mahle turbo 8V 104mm pistons in a standard bore. This is the very last set available - Andial does not have any left, and from what I understand, Mahle is not making more anytime soon.

The set includes the pistons, wrist pins, and rings - $1,300.00

The pistons are coated by Mahle to be used in the factory bore - these are basically the same pistons as used in the 968 turbo S and turbo RS.

Raj, I tried to send you a PM the other night, but got a message that your box was full.

RajDatta

Scott, the PM box was cleaned up so pleae try again.
The factory turbo S/RS pistons have different coatings on their pistons and rings as they used a nikasil blk while the standard 968 is an alusil blk. Both pistons are same spec but not interchangeable due to the difference in cylinder bore material.
Regards.
Raj

Under Pressure Performance

Raj, Absolutely correct. Perhaps I should have been a bit more clear about what I actually meant - What I meant was that these pistons are the same "type" as the S and RS, but coated for use in the stock 968 block.

Sorry for the confusion.