WTB set of pistons for a 944S

[armandodiaz]

I need to replace the rings on my 87 8 valve. The spec state the compression is 10.2:1 and the 44S is at 10.9:1.
Since I was pulling the pistons out anyway I was thinking of putting the S pistions in, if they are not too expensive. They are both 100mm. Has anyone done this, or does anyone see an issue with this?

[armandodiaz]

I accidentally posted on the wrong board....
sorry.

[Team SSR]

The S pistons won't be cheaper and the valve reliefs are completely different.

[todd84944]

The pistons won't work on the 8-valve head. You will bend all of your valves within 10sec of start up.

[armandodiaz]

Thanks for the info. Now, I got my specs form clark's garage. But someone stated it was the wrong info. They stated 87 8valve 944s were 9.7:1 and 88s were 10.2:1. Can anyone give me the right specs?

[Team SSR]

'87 and '88 should be the same CR. In '89 the bore size increased from 100 to 104mm and the CR increased correspondingly from 10.2 to 10.9.
Just a note: Pistons are expensive for these cars. Many rebuilds are performed and the original pistons are re-installed with new rings.

[armandodiaz]

Thanks Team, that's what I figured. I was planning on replacing rings but thought I might have a change of giving it a bump up in compression, with a used set of pistons.
BTW:
Has anyone ever heard of the main bearings going bad or any issues with the the wrist pins or connecting rods? These will problably be the only thing that haven't been worked on and I need to do this job in a weekend. I don't have much down to offer.

[WaA420]

Where ever you got that info from is correct, the '88 had higher compression.

[armandodiaz]

This shows the 87-88 with the same 86 had 9.5

http://www.connact.com/~kgross/FAQ/944faq02.html

[WaA420]

It may show that but the '88 motor is a M44-09 and they had different pistons resulting in a 10.2:1 ratio. These differ from the euro pistons also which had no dish on top, just valve reliefs.

[carsontc]

even if you could use the 16v pistons with the 8v head, your compression ratio would actually go down...its the 16v head that ups the c/r

[fast924S]

Yes the 88 944 engine has the 10.2 CR pistons WaA420 is correct

[924Sman]

Those specs are Euro and incorrect as I stated at CG. The 944 na in 87 is without a doubt 9.7:1 and the 88 at 10.2:1

Dal

[armandodiaz]

Dal you are correct, I opened up my old box of Porsche manuals and looked up the specs. They actually have the 87 USA with 9.5 and ROW with 10.6. In 88 they have all at 10.2.

Does anyone think this would make a big difference if I were to change to the larger compression? It's only .5 difference.

[924Sman]

Yes going to the 88 CR will gain about 10 HP provided the rest of the engine is in spec. No need to use the 88 DME either, just install the 88's and off you go.

In my experience the 88 model can pull me slightly on the track. Small but noticable gain. PCA added weight to the 88 to counter the higher HP.

Dal

[x3m944]

We can offer you a set of custom forged pistons in any size, compression, etc... you want for the 944/924S.

For 511.00 Shipped anywhere in the Continental USA.

Buying used pistons can be a serious gamble, please make sure they are full checked to within spec and still servicable.

We also do sleeves and stroker kits... just ask.

[armandodiaz]

Thanks for the offers but if I can't do it cheap then I'll just use the old ones.

[924Sman]

This much I can tell you the 88 pistons will go for over a grand for sure.

Dal

[x3m944]

... cost is always relative to supply and demand, not to mention which company you buy from.

If get the same or better quality and reliability... I say find the best source for the parts and buy them.

Always more than one way to skin a cat...

[armandodiaz]

Originally posted by 924Sman
This much I can tell you the 88 pistons will go for over a grand for sure.

Dal

That's crazy that's almost as much as what the whole car is worth (sorry for the 944 bashing, but this car has not been good to me).