924Board.org

[TurboJak]

Thinking about buying Kolbenschmidt GT pistons for my 931 (1982 euro type). They are same size and design as the standard 931 Mahle pistons just another make and weight.
Is there any problem with using the GT pistons in the Turbo model??

The GT pistons are a bit cheaper and I am having a hard time finding somewhere here in Europe were I can get new pistons at a reasonable price (Porsche wants $1000++ per piston )
Does anyone know where I can get pistons at a more reasonable price here in Europe??
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'76 924 + '82 924T engine + GT look

[gegge]

Check german Ebay, but please be advised that they are expensive. I have seen two separete sets of 4 pistons the last year costing approx. EUR 700.
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[gegge]

info@porschecentersyd.se

Hej!



931 103 042 01 ska gå att beställa, pris 2749:-inkl.moms



Mvh

Göran
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[TurboJak]

Thnx for the reply. Did see 4 at eBay a while ago but havent seen any since.
Pelicanparts have the pistons at around 380$ but then you have to add tax and shipment and an unknown delivery time, and seems kind of silly to have some pistons shipped from Germany to US and back to Denmark
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'76 924 + '82 924T engine + GT look

[gegge]

http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&ih=011&sspagename=STRK%3AMEDW%3AIT&viewitem=&item=320225419274&rd=1

The Kolbenschmidt are no longer in production, so if you need and find ones - BUY. Retail price is almost EUR 1500 for a set, if not out of stock.

I don´t think you can find them in US for less to be frank. The Carrera GT is "über-rar" over there.

Another solution is to modify VW type 1 Mahle pistons from wwww.dalhems.se As good as and much cheaper.
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs

[ideola]

You can get completely custom forged aluminum pistons from Diamond Racing here in the Detroit area for about $150 per slug. If you add ceramic coating on the top, teflon coating on the sleeves, moly wrist pins, spirolox retainers, and ring set, the price goes up to about $800 for a complete set. They can simply duplicate stock, OR they can make any dish shape and compression ratio you want. Here's pix of mine, which were designed for 90.25 mm stroke:

Custom on the left, stock on the right:




These will accept stock rods and pins, but the CR has been modified to accommodate a stroker crank. I have an extra set if you're interested, or I could assist you in arranging for a custom set directly from Diamond. I have standard size 931 slugs and they've already imaged the 931 head, so much of the design work has already been done.

Here is a post that contains all of the specifications on these pistons, plus the custom rods I had made by Crower:
http://www.924board.org/viewtopic.php?t=23223
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erstwhile owner of just about every 924 variant ever made

[peterld]

WOW! That is something else. Ideola you are truly a hardcore enthusiast. What a nice piece of work those piston guys do. That will be some sort of monster motor when its done.
Cheers Pete

[TurboJak]

gegge, what kind of modifications would be needed to fit in the VW type 1 pistons?? I'm guessing that the CR will be of and there’s something about the pin diameter not being the same as the 931...

ideola, that’s very interesting and sounds like a reasonable price. Do you think they could make a copy of the standard Euro 931 piston (8,5:1 CR)? Its the same size as your standard piston just a smaller dish diameter…
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'76 924 + '82 924T engine + GT look

[ideola]

No question Diamond could duplicate it.

The best option if you wanted to duplicate it exactly would be to send a sample. Alternatively, I have samples of the 8:1 CR pistons they could use as a base, and then they could modify the dish to achieve whatever CR you want, even higher than 8.5:1 if you wanted (there is some merit to higher CR on a turbo car for low end torque provided you can provide proper intercooling).

The latter approach might not result in exactly the same shape of dish as the stock piston, so your desired approach might depend on how particular you are about precisely duplicating the quench area of the stock piston. But there is no question they can deliver whatever you need.

These guys produce standard aftermarket pistons for virtually all street applications, as well big dollar custom stuff for NASCAR and NHRA. They are at the top of the pro ranks, but still able to deliver exceptional prices on jobber orders. I'd be happy to coordinate for anyone who wants to order from them, as I've met Eric Simon personally and have a pretty good professional relationship with him.
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erstwhile owner of just about every 924 variant ever made

[TurboJak]

Ok I know theres been a lot if discussion on this subject but cant seem to find a conclusion…

Is it possible to run the 8.5:1CR 931 engine with the 87mm VW flat top pistons without changing anything other than the 24/22mm bushing?
Will I loose/gain any horses with these pistons in the block??
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'76 924 + '82 924T engine + GT look

[Rasta Monsta]

Flattops would give you more compression than I'm guessing you want.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3