924Board.org

McGyver · Posted: Tue Jul 13, 2010 1:36 am Post subject: Pistons again...

Hi Guys!

I found quite good looking 924 cylinder block for my 931 but unfortunately they had some strange size pistons ... "86,98" or something like that. I've got one good set standard size pistons 86,50 from series I which I wanted use first... and I've got 2 spare pistons with 86,75 size (II) and can't find some other to make a good set.

What I intented to use is that cylinder block and that 931S1 pistons... is there any way to do that. What is a proper size of cylinder for that pistons in turbo (86,50)?

Foto of its:

BTW: If someone got set of 931 pistons for 87mm I could be really interested

But than I have to sell that 2 complete sets first:
931 S1 - 86.5mm
924 - 86,98mm
931 S2 - 86,75mm - just 2 pistons
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Have the block sleeved for your smaller pistons.
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erstwhile owner of just about every 924 variant ever made

RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

I know sleeving isn't cheap.

Custom 931 pistons are $650 a set in any CR and bore size you want, including the coatings. FWIW. Add in the cost of shipping to Europe...can you get a block sleeved for $700? Not sure...but if not, you'll either have to find 87mm 931 pistons (pretty rare, I think) or order new pistons. Or find another block.
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erstwhile owner of just about every 924 variant ever made

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

i dont know the price a set of used pistons go..but you can get JE pistons for 600-900 US$ custom made to your desired CR,bore and they are forged

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https://www.the924.com

Smoothie · Posted: Tue Jul 13, 2010 4:06 am Post subject:

I priced resleeving in NJ a couple years ago. The quote for just one cylinder was right around $700. ...So $700 x 4 =

.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

The fact that the cost of re-ringing OEM gets you almost halfway to buying custom slugs with modern manufacturing techniques makes using OEM extremely hard to justify, IMO.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

McGyver · Posted: Wed Jul 14, 2010 6:17 am Post subject:

I ask tooday about that block sleeving and they say it should cost about 120$ or 100 Euros here in Poland. So I think this will be best way to go futher with that engine.
What is proper diameter hole for 86,5mm piston? what gap between cylinder block and piston... I know about 0,3-0,5mm gap between end of ring but this don't tell what is proper size of that.
I can't find it in Haynes - maybe in Workshop manuals they write something about that.

Or maybe someone in Europe have some original pistons set for sell in some oversize diameter.?? could be from S1... but S2 will be much better.

I've got one good nominal block for 86,50 but it has crack on one side of water cooling maybe after winter or something... and it's too risky to use it
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

i have 3 S1 pistons of 86.95 the forth one is damaged by detonation and melting.
_________________
Supercharger and EFI kits
https://www.the924.com

McGyver · Posted: Thu Jul 15, 2010 7:02 am Post subject:

I found set of 86,95 S1 pistons... now I'm waiting for photos but I think that should solve my problem easly and with new rings all tolerances should be quite enought.

I'm wonder when someone find some more 86,75 S2 pistons

So now I try to get that oversize pistons and then I think I sell the rest - 931 S1 nominal, 924 oversize and that two S2...
_________________
931 82' - 5000km after full engine rebuild

SOLD: 924 81' N/A- with turbo gearbox "dogleg" - great but mysterious car

www.mauser98k.internetdsl.pl - if someone like german rifles (English version avalible)

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Good luck finding new rings for the 87mm pistons...those are going to cost you a pretty penny (as the saying goes).
_________________
erstwhile owner of just about every 924 variant ever made

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

will JE pistons supply rings for their custom pistons?
_________________
Supercharger and EFI kits
https://www.the924.com

Joes924Racer · Posted: Thu Jul 15, 2010 11:21 pm Post subject:

* How bout having a knurled set installed (wonder what other ways
there are to expand.) No dont think JE comes with rings they might but
dont think so. Good luck.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

peterld · Posted: Fri Jul 16, 2010 11:48 pm Post subject:

87mm (86.95) piston ring sets available from EBS Racing for $92.50........down from $145 some eighteen months or so ago. Ask for Don.
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80/81 932/8 ROW

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI