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donistook
Joined: 13 Jan 2023
Posts: 3
Location: Fort Worth, Texas
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 Posted: Sat Jan 14, 2023 2:41 am Post subject: 924 turbo stroker crank |
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I am sure this has been discussed before, but I am new to this forum. I am building up a 924 turbo engine for a customer, and am looking into a stroke increase. I am not new to these, as I have built many a race engine, and raced the 924 in SSA, 924 DP in SCCA DP, and the 924 Carrera GTR in IMSA…along with the 944 in the IMSA Firestone Firehawk series. So….anyone have a lead on a stroker crank, or a company that can offer such?? Thanks!
Don Istook 817 332-6547. Rswerkes4@gmail.com
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Started racing Porsches in 1977, and was one of the seven original Porsche teams in the IMSA Firestone Firehawk series. In PWC, we raced with VW and Audi. In IMSA, we raced for Porsche, VW, Audi, Pontiac, Chevrolet, and Toyota. I renovate Porsches |
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Cedric
Joined: 27 Aug 2004
Posts: 2610
Location: Sweden
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924RACR
Joined: 29 Jul 2001
Posts: 8810
Location: Royal Oak, MI, USA
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| Posted: Sun Jan 15, 2023 2:22 am Post subject: |
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Welcome to the forum, Don!! Glad to have you hear.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype |
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donistook
Joined: 13 Jan 2023
Posts: 3
Location: Fort Worth, Texas
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| Posted: Sun Jan 15, 2023 4:10 am Post subject: |
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I forgot…I also raced the 924 in SCCA ITB. I was around a lot of the racing with the DP 924 and the 924 GTR’s…many years ago. My street car was a 924 Carrera GTS Club Sport.
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Started racing Porsches in 1977, and was one of the seven original Porsche teams in the IMSA Firestone Firehawk series. In PWC, we raced with VW and Audi. In IMSA, we raced for Porsche, VW, Audi, Pontiac, Chevrolet, and Toyota. I renovate Porsches |
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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Mon Jan 16, 2023 2:58 am Post subject: |
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There was a gentleman here who might still shows up from time to time but is out of the 924 game. He had a GT as well for a time. You will find his posts here filled with a wealth of knowledge (Dan / Ideola), He built a stroker using a stock crank that was welded and reground. Technically he built three. Two welded and one with smaller journal rods yet to be tested I believe. That one was just offset ground for the smaller rods. Someone else owns that car. Just throwing that out here since you asked. I have one of his former cars and broke the engine down. Crank still looked decent.
around 2.2 Liters
This is the only picture I can post quickly. I was playing around with rods so ignore them.
Non welded smaller journal rod motor. I'll see if I can find a pic of this crank. His version of a D-Prod
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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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Mike9311
Joined: 14 Dec 2004
Posts: 1678
Location: Chicago-ish
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| Posted: Mon Jan 16, 2023 3:05 am Post subject: |
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The non-welded offset ground crank. Need to find how much stroke he achieved. Details here but you could do custom rods and pistons to suit your needs. Journal size not an issue with lighter pistons and rods
https://www.924board.org/viewtopic.php?p=332225
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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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Fifty50Plus
Joined: 28 Feb 2008
Posts: 1357
Location: Washington DC area
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| Posted: Mon Jan 16, 2023 3:40 am Post subject: |
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Don,
I was spectating at the Road Atlanta Runoffs from the mid '70s til they moved. I say your D-Prod 911 in '80 or '81 in the rain and decided that was the car for me. I built a similar Targa and raced it very successfully in Regionals for 10 years in the NE Div (too poor to chase Nationals). I moved to IT-B in the '90s with a BMW 2002 and finally wound up with a 924 in IT-B after seeing Vaughan Scott race his at Road Atlanta. Much advice from he and Dan Beckett (Idola) helped me continue to be successful in Regional racing. I converted my car to H-Prod this past year and plan on running Nationals (oops, Majors) this year for my first Runoffs attempt at VIR.
The folks on this board are a wealth of knowledge and help as you've seen with the first responses in this thread.
Regards,
Chuck Allard
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1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car |
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donistook
Joined: 13 Jan 2023
Posts: 3
Location: Fort Worth, Texas
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| Posted: Mon Jan 16, 2023 5:06 am Post subject: |
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Wow! That is a great memory! Yes, the DP 911 targa I raced was an exceptional car. I think I had 10 wins, plus the 3rd at the runoffs that year (against several 924 DP cars). It is in California now, and Mike Sweeney is restoring it. I have a 944 Spec car we are building, but will be selling it as I bought another Audi RS3 LMS TCR car. Best wishes!!
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Started racing Porsches in 1977, and was one of the seven original Porsche teams in the IMSA Firestone Firehawk series. In PWC, we raced with VW and Audi. In IMSA, we raced for Porsche, VW, Audi, Pontiac, Chevrolet, and Toyota. I renovate Porsches |
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kondzi
Joined: 02 Jul 2018
Posts: 485
Location: Poland/EU
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| Posted: Mon Jan 16, 2023 8:52 am Post subject: |
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+1 for offset grind, these cranks are bulletproof, why weld one and risk failure?
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Konrad
'89 951 US
'88 Mustang 5.0 LX Convertible (factory specs)
'84 911 Carrera 3.2 RoW (factory specs)
'81 931 RoW (TBD)
'81 Ford Capri 2.8i (factory specs)
'79 Ford Capri 2.9 (heavily modded) |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Wed Dec 06, 2023 5:54 am Post subject: |
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| kondzi wrote: | | +1 for offset grind, these cranks are bulletproof, why weld one and risk failure? |
Because there's only enough material to get to 2.1L with the offset grind method. Welding and regrinding can get you to 2.2L. There were unsubstantiated rumors of a 2.4L stroker from one of the big time racers from back in the day (Dave somebody???, can't remember the name), but they never posted full specs, and based on my research, I think the magazine article mis-stated or mis-calculated what they actually achieved. The cylinder skirts in the block would require massive removal of material to accommodate any more stroke due to the increase in rod angularity.
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erstwhile owner of just about every 924 variant ever made |
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Kenodog
Joined: 25 Jun 2003
Posts: 2651
Location: Vancouver,B.C.
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| Posted: Wed Dec 06, 2023 8:49 am Post subject: |
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Back in the day I scored an Oettinger / Okrasa crank that was then plundered from me by Mikri1984, (total scumbag.)
After that I researched getting one made, welded and ground by someone, and spoke with two very reputable companies in Commie-fornia. They both said it was a breeze with these cranks because they were so heavily built. One was Lopez Crankshafts and one was Castillo's Crankshafts.
Leigh
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1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140 |
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ideola
Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI
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| Posted: Wed Dec 06, 2023 9:06 am Post subject: |
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| Kenodog wrote: | | They both said it was a breeze with these cranks because they were so heavily built. |
The one thing our crank guy said was that these cranks appeared to have been nitrided or put thru some other similar hardening process, which did make processing them more of a challenge than he anticipated. But to Leigh's point, I don't think there has ever been any concern about the stoutness of these cranks. They were designed for a diesel application, after all.
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erstwhile owner of just about every 924 variant ever made |
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Beartooth
Joined: 05 Apr 2022
Posts: 206
Location: Roberts, MT
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| Posted: Wed Dec 06, 2023 6:10 pm Post subject: |
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It seems a little impractical trying to stroke this motor unless you're pushing the envelope within the constraints of some racing rulebook, or just throwing money around. If I had really deep pockets, a billet crank be would what I'd gun for: whatever stroke I choose (I'd keep it small enough to avoid clearancing the block), and I'd have my pick of rods too. That's a lot more money, but both are very marginal gains for the money. Ultimately, I'd think you could either build power with boost, in which case the stock bottom end is plenty stout (except for needing a piston upgrade), or if you wanted more motor, you'd bite the bullet and buy a 944 S2 or 968 - or 924S and swap engines if you wanted the tofa look. If I had all the money in the world, I'd spend $10-20k rebuilding mine and be happy with what I got, but for someone just wanting power, the M44 makes more sense. I think I'm agreeing with kondzi here either way though: it's hard to see a welded crank not getting weaker, and it just doesn't buy you that much.
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1980 931 diamond in the rough |
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Cedric
Joined: 27 Aug 2004
Posts: 2610
Location: Sweden
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| Posted: Wed Dec 06, 2023 7:48 pm Post subject: |
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| Beartooth wrote: | | It seems a little impractical trying to stroke this motor unless you're pushing the envelope within the constraints of some racing rulebook, or just throwing money around. If I had really deep pockets, a billet crank be would what I'd gun for: whatever stroke I choose (I'd keep it small enough to avoid clearancing the block), and I'd have my pick of rods too. That's a lot more money, but both are very marginal gains for the money. Ultimately, I'd think you could either build power with boost, in which case the stock bottom end is plenty stout (except for needing a piston upgrade), or if you wanted more motor, you'd bite the bullet and buy a 944 S2 or 968 - or 924S and swap engines if you wanted the tofa look. If I had all the money in the world, I'd spend $10-20k rebuilding mine and be happy with what I got, but for someone just wanting power, the M44 makes more sense. I think I'm agreeing with kondzi here either way though: it's hard to see a welded crank not getting weaker, and it just doesn't buy you that much. |
Thats very true, probably one of the worst bang for the bucks mods possible considering the effort needed. A fun project if you have a very big budget for the build, or a tricky rulebook. Though i would rather put that money on the turbo system, and possibly some head porting if i had to chose where to burn money and if there werent a rulebook i had to obey:) Though its always fun to see weird modding even if its not the most efficient way!
reminder, 500+Nm on the std bottom end is more than enough for most anyway. Play with the strengths of the engine, like the std crank and rods etc.
https://www.924board.org/viewtopic.php?t=45866&postdays=0&postorder=asc&start=0
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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Kenodog
Joined: 25 Jun 2003
Posts: 2651
Location: Vancouver,B.C.
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| Posted: Thu Dec 07, 2023 4:11 am Post subject: |
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| Beartooth wrote: | | It seems a little impractical trying to stroke this motor unless you're pushing the envelope within the constraints of some racing rulebook, or just throwing money around. If I had really deep pockets, a billet crank be would what I'd gun for: whatever stroke I choose (I'd keep it small enough to avoid clearancing the block), and I'd have my pick of rods too. That's a lot more money, but both are very marginal gains for the money. Ultimately, I'd think you could either build power with boost, in which case the stock bottom end is plenty stout (except for needing a piston upgrade), or if you wanted more motor, you'd bite the bullet and buy a 944 S2 or 968 - or 924S and swap engines if you wanted the tofa look. If I had all the money in the world, I'd spend $10-20k rebuilding mine and be happy with what I got, but for someone just wanting power, the M44 makes more sense. I think I'm agreeing with kondzi here either way though: it's hard to see a welded crank not getting weaker, and it just doesn't buy you that much. |
When I got the stroker it was in a 70's NA car from a tow yard. The guy bent the front end and I got the car for $500. He obviously didn't know what he had and neither did I until I was driving it to the ferry to bring it home. Throaty and grumbly in all the right ways, drifted a few corners with ease ...it was crazy. It was the first NA car I had ever driven and was thinking what the hell does everyone complain about these, it's got way more torque than my modded 931..
Although on a 931 you only need an I/C and boost controller to bump up 50 hp for very little money so....yeah, go little turbo cars !
_________________
1979 Euro 931, Olive
1981 931, Sabine
1991 Ford Ranger XLT 4x4, Ricky
1996 Ford E-350 ex-FedEx Van
2014 Mazda CX-5 (Kinderwagon)
2019 KTM 790 Adventure
2024 KLX300
2024 KLX140 |
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