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Jaspermaertz
Joined: 01 Apr 2023 Posts: 3 Location: Netherlands Bocholtz
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Posted: Tue Apr 04, 2023 3:53 pm Post subject: 924 Turbo Pistons |
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Hi
im a rebuilding my engine and i need 1 new piston.
the size on the piston is 87.45. and i cant find one used or new..
can anyone help me? |
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morghen
Joined: 21 Jan 2005 Posts: 8883 Location: Romania
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Posted: Tue Apr 04, 2023 4:00 pm Post subject: |
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87.45? that sounds like non standard, you sure its not 86.45? _________________ https://www.the924.com |
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Jaspermaertz
Joined: 01 Apr 2023 Posts: 3 Location: Netherlands Bocholtz
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Posted: Tue Apr 04, 2023 11:18 pm Post subject: |
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Nope its really 87.45 |
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Cedric
Joined: 27 Aug 2004 Posts: 2610 Location: Sweden
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Posted: Wed Apr 05, 2023 12:49 am Post subject: |
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Its the third and last oversize according to the spec manual, finding such a pistons wont be easy. _________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
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Karlio
Joined: 17 Nov 2019 Posts: 67 Location: UK
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Posted: Thu Apr 06, 2023 8:52 am Post subject: |
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Friesinger motorsport have them in stock, around €600 a piston |
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Mike9311
Joined: 14 Dec 2004 Posts: 1678 Location: Chicago-ish
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Posted: Fri Apr 07, 2023 8:35 am Post subject: |
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Karlio wrote: | Friesinger motorsport have them in stock, around €600 a piston |
This needs to read...
Friesinger motorsport have them in stock, around €600 a piston for the discerning 924 owner. Simply asking for the price implies one cannot afford _________________ 1980 931 since 1989
1981 Ideola 931 Club Sport
1982 931 Entwicklungsfahrzeug
1979 924 NA ohne 650 mit 471
1982 931 Red Resurrection - 951 IC
1982 931 parts car / resurrection?
1980 924 NA (R&D lightweight)
1982 931 wana-be GTR race car |
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Jaspermaertz
Joined: 01 Apr 2023 Posts: 3 Location: Netherlands Bocholtz
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Posted: Wed Apr 19, 2023 5:16 am Post subject: |
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Bought the piston at Friesinger! the piston cost 300 euros ex VAT..
now im looking for a set of pistonrings for the remaining pistons.. 87.45. or could i use 87.5 rings? |
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Coco_Lev
Joined: 04 May 2020 Posts: 81 Location: France
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Posted: Fri Apr 21, 2023 9:49 pm Post subject: |
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Jaspermaertz wrote: |
now im looking for a set of pistonrings for the remaining pistons.. 87.45. or could i use 87.5 rings? |
There is one single ring size for each cylinder repair stage. You can theorically use the 87.5 rings. Just need to check for the ring gaps. _________________ https://classic-line.eu |
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MikeJinCO
Joined: 08 Jun 2010 Posts: 1228 Location: Maysville, Colorado
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Posted: Fri Apr 21, 2023 11:12 pm Post subject: |
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I worked for a piston ring company for15 years. There is nothing special about 95% of the piston rings made, a few slight changes to get them to twist, taper faced or barrel faced, etc. Back at the time except for a barrel faced top ring most of the changes were to the second ring to change sealing/scraping characteristics. If you find any ones rings of the proper bore then the only major difference is the thickness and pistons are easily machined for other rings. I believe Mitsubishi makes engines with a bore of similar size for one.
If I recall correctly, the only thing about the 931 ring that was a little different is that the top ring is thinner than was typical at the time, These days it would be a very common or even thick for a modern performance motor. I believe Wiseco has a listing of there rings by bore size and thickness and would be a good place to start.
An alternative is to go to Circle Seal, they make rings by rolling steel rather than machining castings so can produce a set of any size needed. A caution on them tho is that I have heard, very unconfirmed, that their rings are very unhappy if the ring lands are not perfectly parallel. ie worn.
When I was building my race car motor with old 931S2 pistons and a NA head, no 931 rings were available so we just machined the pistons for thicker standard NA rings. Worked fine _________________ Mike
'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild) |
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Karlio
Joined: 17 Nov 2019 Posts: 67 Location: UK
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Posted: Sat Apr 22, 2023 4:48 am Post subject: |
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Oversize rings are very rare these days both n/a and turbo. A set of standard turbo rings are as much as the piston you just bought.
Total seal do gap less rings that should fit. totalseal.com
Or as you are in Holland and speak the lingo you could try www.thn.nl and see if they have got some rings. |
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MikeJinCO
Joined: 08 Jun 2010 Posts: 1228 Location: Maysville, Colorado
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Posted: Sat Apr 22, 2023 8:52 am Post subject: |
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I just looked up Wiseco . Mitsubishi 4G63 87.50 bore, 1.0,1.2/2.8 thickness. _________________ Mike
'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild) |
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