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MikeJinCO
Joined: 08 Jun 2010 Posts: 1227 Location: Maysville, Colorado
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Posted: Thu Mar 25, 2021 10:14 pm Post subject: |
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When I did my 931S2 pistons I had basically 0 deck clearance and had to cut pockets. From the clay marks they are a bit deeper than necessary.
https://imgur.com/d9R2u11
https://imgur.com/7WdNwaO _________________ Mike
'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild) |
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Juho
Joined: 03 Oct 2018 Posts: 377 Location: Finland
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Posted: Thu Mar 25, 2021 11:20 pm Post subject: |
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with na head? |
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MikeJinCO
Joined: 08 Jun 2010 Posts: 1227 Location: Maysville, Colorado
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Posted: Fri Mar 26, 2021 12:52 am Post subject: |
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Yes, NA head _________________ Mike
'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild) |
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anthonimartini
Joined: 17 Feb 2020 Posts: 240 Location: portland oregon
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Posted: Fri Mar 26, 2021 1:26 am Post subject: |
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the s1 and s2 931 pistons have the same height correct? just a different bowl shape/volume? i have a nice set of s1 pistons i considered getting the ring lands machined to accept NA sized rings for reliability. i didnt consider using them for a bump in compression over the euro NA pistons. how much volume did those reliefs add to the chamber? _________________ ive saved alot of 924's
current:
79 MochaSchwartz 931
83 944
87 924S
Instagram @anthoni.jpeg
formerly known as turbellion, lost password. |
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safe
Joined: 18 Mar 2017 Posts: 583 Location: Sweden
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Posted: Fri Mar 26, 2021 1:31 am Post subject: |
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anthonimartini wrote: | the s1 and s2 931 pistons have the same height correct? just a different bowl shape/volume? i have a nice set of s1 pistons i considered getting the ring lands machined to accept NA sized rings for reliability. i didnt consider using them for a bump in compression over the euro NA pistons. how much volume did those reliefs add to the chamber? |
Whats wrong with the turbo rings? _________________ /Magnus, Stockholm Sweden
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Porsche 924 -79 NA, EFI and Turbo.
Porsche 931 -79
Porsche 911 -77, 3.2 Targa
Porsche 911 -69, 3.6, Coupe |
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Rasta Monsta
Joined: 12 Jul 2006 Posts: 11723 Location: PacNW
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Posted: Fri Mar 26, 2021 5:06 am Post subject: |
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safe wrote: | Whats wrong with the turbo rings? |
They cost One Jillion Dollahs (per slug). _________________ Toofah King Bad
- WeiBe (1987 924S 2.5t) - 931 S3
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MikeJinCO
Joined: 08 Jun 2010 Posts: 1227 Location: Maysville, Colorado
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Posted: Fri Mar 26, 2021 5:20 am Post subject: |
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Welcome to my world. I bought the pistons for about $100, by the time I bought the rings, had the pistons machined for the NA rings and then got the valve pockets cut I was within about $100 of just getting a set of new forged lightweight JE pistons with rings and pins. _________________ Mike
'67 MG Midget Dp
'71 Ocelot Dsr Kawasaki 1000(under rebuild) |
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anthonimartini
Joined: 17 Feb 2020 Posts: 240 Location: portland oregon
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Posted: Fri Mar 26, 2021 7:58 am Post subject: |
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and they break. at least under boost. i can get them machined to fit the larger rings and use a decent set of rings for about half the price of the oem sized rings. the are a bit more efficient then the NA rings as the thinner contact area reduces friction. but ill take the reliability. _________________ ive saved alot of 924's
current:
79 MochaSchwartz 931
83 944
87 924S
Instagram @anthoni.jpeg
formerly known as turbellion, lost password. |
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dial67
Joined: 07 Apr 2013 Posts: 20 Location: DeRidder, LA
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Posted: Fri Aug 05, 2022 9:28 am Post subject: VW Type 1 pistons |
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Did the VW pistons work well in your build? If so how much deck height? It would seem that the block would have to have considerable material removed. I am interested in using the VW pistons because they will be easy to source. I have had quite a run around trying to buy pistons. |
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