FRporscheman

I once read here that some people like using the 944 S2 pistons in their engines. I don't know the 928 engines very well but I'd assume this would be for the 5.0L 16v guys looking to drop compression? Like I said I don't know. Well if people still use them in their builds, I have a set (4) of 104mm S2 pistons I don't need. I also have a set (4) of 104mm 968 pistons. AFAIK they are identical except the 968 pistons are forged, and S2 units are cast. I don't even know what these are worth...?

John Veninger

They are typically used to build a 6.4L stroker motor. Small market for them.

Are they new or used? I may be interested in them as spares.

Vilhuer

All 32V 928 use 100mm pistons. Kolbenschmidt 968 pistons can be used in 104mm bored 928 block. All 944 S2 pistons have too much material in skirt to work in 928 block without major mods. Is your 968 set similar to bottom row center pistons in below picture?

John Veninger

Have to somewhat disagree with the 944S2 pistons having to much material. Depends on which manufacture.
I run 944S2 KS pistons without any modification. Maybe the 944S2 Mahle have more of an issue.

Vilhuer

Do Kolbenschmidt 944 S2 pistons have full skirt like in Mahle 944 S2 pistons in previous messages picture or non full skirt design like 968 KS pistons in below picture?



As below videos try to show I think there is no way full skirt piston can be used in 928 block when stroke is 95.25mm as standard 3.75" stroker crank. Unless block is modified and/or skirt is exceptionally short.


http://www.youtube.com/watch?v=hTrl2Acrlnc


http://www.youtube.com/watch?v=E5uCM4CWYSs

FRporscheman

They are all used. The 968 pistons have about 180k miles on them and the S2 pistons have somewhere between 120k and 150k. How much is each set worth?

John Veninger

They are the non-full skirt.

Vilhuer

Thats quite a lot of miles. As their condition can be very good or useless we need to see pictures of skirt area and diameter measurement taken from WSM specified location. See attached picture for correct procedure. Also skirt coating must be ok everywhere and ring grooves within tolerances. What is tolerance group of the 968 pistons?

That explains why they work. So both 944 S2 and 968 pistons are ok for stroker build as long as they are made by Kolbenschmidt. Mahle versions will not work without serious mods. It seems most 944 S2 got Mahles and most 968 use KS.

mark kibort

so the 944S2 pistons from KS will work, but arent they for 2 valve strokers, or do the piston valve reliefs matter?

can you make a stroker block with both sets. 944s on one side and 968s on the other?

mk

FRporscheman

I suppose you could, if you take 10 grams off the rods or something to compensate for the difference in mass.

The 968 pistons I have are the KS type with non-full skirts. I'll check the S2 pistons later and post pics of all of them.

I remember the thread I read before about 928s using these pistons was regarding 2v strokers and S2 pistons. They were saying the 4 valve reliefs are partially cut away and 2 new valve reliefs are cut in.

Mark Anderson

I have 2 sets of used S2 pistons and 2 sets of 968 pistons. $400 per set. I also have a few new 928 104.5 pistons.

Vilhuer

They work much better in 4 valve strokers as head design is exact same as in 928. Very few people make 2V strokers and in doing such beast it doesn't matter which Porsche 104mm pistons are used. All available options will result wrong compression ratio.

John Veninger

Just for reference mine were 944.103.058.10

FRporscheman

Mark, when you say "set", is that 4 or 8?

Mark Anderson

there are 8 in my sets