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Cedric
Joined: 27 Aug 2004
Posts: 2762
Location: Sweden
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 Posted: Wed Oct 01, 2025 5:08 pm Post subject: |
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| Mclaren924 wrote: | | Cedric I believe the exact specs are a 47,4 mm compressor wheel inlet, with a 66mm compressor wheel outlet that winds up being 72mm with the extended tip. Ultimately I'm not a turbo genius by any shape or form, the main constraints with turbo choice was a relatively bolt in option. The customer was actually wanting a 8ar housing from a gts byt Simon informed us they are very hard to source and could be a long wait as well as they are quite laggy compared to the setup he has spec'd for us. If this car made 300 wheel with 91 on a dyno, the customer would be ecstatic and so would I. With that also in mind, a bigger less responsive turbo was ruled out. I'm very confident that this car will be an absolute thrill to drive and has room for more power if E85 was ever brought to the table as an option. |
Then he have done some machining to fit that wheel, it will probably work very well. I dont think the 8cm2 housing would be necessary either, the better the compressor efficiency the farther you can use a certain size turbine housing, since it will need less drive power to achieve the same boost and flow. The limiting factor would probably be the 91 fuel which sucks quite a bit, be sure to have good intercooling. E85 on the other hand would enable lots of sillyness 
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1980 924 Turbo
www.instagram.com/garagecedric/ |
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Cedric
Joined: 27 Aug 2004
Posts: 2762
Location: Sweden
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| Posted: Wed Oct 01, 2025 5:27 pm Post subject: |
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| Mclaren924 wrote: | Sorry for lack of updates, have had a martini car getting a complete mechanical/electrical restoration and it has needed basically everything gone through. It could be a 5 page thread of me just posting on that car, fixing others peoples mistakes is always 2x worse than fixing a mechanical failure.
Not much has been done to 931 project as it just got it dropped off to paint a few days ago and machine shop is supposedly getting everything done by next week. Currently not much to be done as I don't have the chassis or the motor. I do have the trans and TT so have been getting that all assembled and mocked up to make sure it's all there and will be no issue come install time. Currently toying around with short shifter. 100% credit to Lizard for original design and Ideola for posting the specs and having a good thread talking about it.
https://www.924board.org/viewtopic.php?t=33456
Making a 3d printed mock up right now out of some cheap abs to test out the throw. Will print a Carbon Fiber nylon version after I get the design to tolerance and let a buddy test it out in his s1 turbo and see how he likes it. Really aiming for just an improvement of the stock to make spirited street driving more enjoyable. If we like the feel and how it drives, I'll machine one up and go from there.
On an engine related note, customer was interested in doing a lightweight flywheel and pp setup. I know the pp is an easy one to find as its a 915 part and somebody is making those for sure. The lightweight flywheel on other hand I'm not too sure is being made as an aftermarket part. Apparently the s2 flywheel is a good bit lighter? Will have to weigh some tomorrow to confirm this. I'm sure it's in this forum somewhere too lol. |
Ive ran that shifter for years, it works well, but I had some interference issues with the body insulation if i remember correctly. I spaced down the front bushing for the shifter to move the shift rod down slightly which solved that issue.
Regarding the flywheel, they are all very different , aswell as the different specific pressure plates they fit to(there are some combinations that were on these), so the easiest way would be to just shave off some weight of the current flywheel, the S1 wheel have some meat that could easily be removed, i even have on of those made years ago that I never used
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1980 924 Turbo
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Mclaren924
Joined: 13 Oct 2021
Posts: 245
Location: Oceanside CA
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| Posted: Wed Oct 29, 2025 2:10 am Post subject: |
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You are right Ciprian, I believe the housing was indeed machined to accommodate bigger wheel.
After talking with the customer, we just opted for a stock s1 flywheel. Going to take a page out of your book and stick with what the engines design benefits and just feed it more boost and keep rpm down. Ultimately the head is completely stock minus an adjustable cam pulley so the top end couldn't handle extreme abuse either. We may run a set of stiffer springs that mittlemotor has.
Just got the centerforce pressure plate and the flywheel and morghens crank pully dropped off to machine shop and they should have it all balanced and ready to go for us tomorrow.
The body shop has the engine bay almost completely stripped down and has a good paint match ready to go, hoping that's done this week too. We shall see
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1980 931 "Salt" Bucket wannabe racer (Dreaming)
1979 924 Sebring "Pepper" -Sold
1977 924 Slicktop "Pennie"-Most likely parts
1979 3/5 gt clone 924- Shop Test Car |
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