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Supercharged 924 NA
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gegge  



Joined: 27 Jul 2007
Posts: 1084
Location: Sweden

PostPosted: Thu Apr 30, 2020 5:39 pm    Post subject: Reply with quote

Would it be possible to pre-charge the Roots with a turbo?
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs
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morghen  



Joined: 21 Jan 2005
Posts: 8213
Location: Romania

PostPosted: Thu Apr 30, 2020 6:18 pm    Post subject: Reply with quote

Yes, it is possible to help out a 931 turbo in lower rpm but not easy.
I was actually thinking about my old 924 turbos when i first drove this supercharged 924 as there is boost right from idle...or the milisecond you open the throttle you are already on boost regardless of the RPM.
It feels like my Cayman in terms of responsiveness.
I still have my 931 engine and i'll test-fit the charger on that engine to see what would be needed to make it work for the 931 as well.

Until then, i'm improving the system every day a little bit.
I want to drive it again during this weekend with a wideband and data logging on so i can WOT it.

Sealing between the two tubes is done by flush fit and an oring.

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SUPERCHARGED Ruby-sh 924
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CÚdric  



Joined: 27 Aug 2004
Posts: 2000
Location: Sweden

PostPosted: Thu Apr 30, 2020 7:43 pm    Post subject: Reply with quote

Great that you put this project on here aswell! We ve been discussing it alot during the process so I have nothin more to add


I think i sent these before to you, but could be fun to add here, would be interesting to see if those performance numbers are close to what you will end up with in the end. According to the article they used water injection to mitigate detonation, hopefully it will be enough with 98octane fuel for you to get to the same point.




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morghen  



Joined: 21 Jan 2005
Posts: 8213
Location: Romania

PostPosted: Thu Apr 30, 2020 9:12 pm    Post subject: Reply with quote

Cedric, thank you for the outstanding level of input, greatly appreciated as always!

In comparison to that old-school supercharger i expect no need for water injection or any type of cooling because of the following differences:
-lower boost level (5 psi vs 7psi)
-much better fuel today vs back then
-much more thermally efficient supercharger
-fuel injected instead of carbs
-charger is not throttled
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CÚdric  



Joined: 27 Aug 2004
Posts: 2000
Location: Sweden

PostPosted: Fri May 01, 2020 12:22 am    Post subject: Reply with quote

morghen wrote:
Cedric, thank you for the outstanding level of input, greatly appreciated as always!

In comparison to that old-school supercharger i expect no need for water injection or any type of cooling because of the following differences:
-lower boost level (5 psi vs 7psi)
-much better fuel today vs back then
-much more thermally efficient supercharger
-fuel injected instead of carbs
-charger is not throttled


Yeah, i think there is much better chances for your setup with todays 98octane and better supercharger. And you also have a wideband to tune and measure with, which is a massive advantage.
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gegge  



Joined: 27 Jul 2007
Posts: 1084
Location: Sweden

PostPosted: Fri May 01, 2020 5:40 am    Post subject: Reply with quote

I still don┤t understand the Butera solution. The k-jet (CIS) was capable of delivering fuel at the right A/F ratio. Why even consider (ONE) carb? And what happened to the runners?

The M45 presented here is by far the best hp per buck ever spent!
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Carl Fredrik Torkildsen

924 turbo -81 Carrera GT RESTOMOD
924 turbo -80 Dolomite De Luxe
924 -85 DP kit, BBS RS, M030 and tuned engine
924s -86 Black on black turbo with Fuchs
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CÚdric  



Joined: 27 Aug 2004
Posts: 2000
Location: Sweden

PostPosted: Fri May 01, 2020 5:52 am    Post subject: Reply with quote

gegge wrote:
I still don┤t understand the Butera solution. The k-jet (CIS) was capable of delivering fuel at the right A/F ratio. Why even consider (ONE) carb? And what happened to the runners?

The M45 presented here is by far the best hp per buck ever spent!


I think the kjet was just new and scary, and they where used to carbs, probably not a fully rationale decision. Yeah, runner length was slightly compromised to say ar least
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morghen  



Joined: 21 Jan 2005
Posts: 8213
Location: Romania

PostPosted: Fri May 01, 2020 7:20 am    Post subject: Reply with quote

dunno why carbs..but they also ditched the cam cover
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joewest  



Joined: 06 Oct 2005
Posts: 194
Location: Portland, OR

PostPosted: Sat May 02, 2020 4:42 am    Post subject: Reply with quote

Awesome upgrade!
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'79 924 Track Prepared (currently under supercharger upgrade)
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morghen  



Joined: 21 Jan 2005
Posts: 8213
Location: Romania

PostPosted: Sat May 02, 2020 7:20 am    Post subject: Reply with quote

Second generation of functional prototypes now on the car.
Assembly ease much improved but room for better.
I still dont have an AFR on the car but seeing the plugs look good and only boosting a maximum of 0.2bar its safe to drive a bit lively...no WOT and no higher than 4500RPM tho.

Here is a short video of just driving around.
Its without question considerably quicker than when NA, revs up faster.
Gets up and goes instantly, no lag, no waiting for boost or rpms to increase.
pedal = GO
My butt dyno is that on a technical circuit it would be quicker than a standard 931 because of how quickly it picks up after slowing down for a corner.
Its nowhere near as dramatic as an early turbo, it feels and drives like a big NA...but sounds nothing like a NA. Video is poor quality but you can have an idea.
I suggest loud volume as the recording isnt very loud.
Car on toyo proxes, and ambient temp was approx 22deg C.

https://youtu.be/VxjylhPUoYs


Fueling looks decent so far, we'll see how it behaves on WOT and higher RPM after i hook up the AFR.

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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2066
Location: MI

PostPosted: Sat May 02, 2020 9:35 am    Post subject: Reply with quote

It does sound pretty quick..
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Sndtech  



Joined: 23 Apr 2013
Posts: 47
Location: Commack, NY

PostPosted: Sat May 02, 2020 4:44 pm    Post subject: Reply with quote

Real sweet .. sounds great and seems very responsive with instant power..
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1977 924 Martini |1979 924 N/A Dolomite Grey | 1980 924 N/A Minerva Blue
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1062
Location: The Netherlands

PostPosted: Sun May 03, 2020 4:24 pm    Post subject: Reply with quote

Cool video!
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937 trackday car
Series 2 engine
951S turbo and intercooler
937 DITC
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Euro924S2  



Joined: 06 Mar 2008
Posts: 184
Location: UK

PostPosted: Mon May 04, 2020 11:44 pm    Post subject: Reply with quote

Great work mate! The low down torque of the SC is it's best feature. It also makes it very predictable in the wet.

Keep the updates going!

Cedric, where did you find that article on the old SC kit? would love to read that if you have a link or higher quality image of the text?
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UK spec '83 N/A with 931 motor with Eaton MP62 'charger @ 15psi. EFI - 565cc inj. Standalone Adaptronic ECU. 951 FMIC. Ally rad. Twin throttle. Recirc valve. Custom manifolds and CAI. 232bhp
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CÚdric  



Joined: 27 Aug 2004
Posts: 2000
Location: Sweden

PostPosted: Tue May 05, 2020 12:05 am    Post subject: Reply with quote

Euro924S2 wrote:
Great work mate! The low down torque of the SC is it's best feature. It also makes it very predictable in the wet.

Keep the updates going!

Cedric, where did you find that article on the old SC kit? would love to read that if you have a link or higher quality image of the text?


Its in the "924 Gold portfolio" book, I can make a scan of it, but every 924 owner should have that book anyway
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