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gegge
Joined: 27 Jul 2007 Posts: 1124 Location: Sweden
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Posted: Thu Apr 30, 2020 4:39 pm Post subject: |
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Would it be possible to pre-charge the Roots with a turbo? _________________ 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: 8879 Location: Romania
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Posted: Thu Apr 30, 2020 5:18 pm Post subject: |
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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.
_________________ https://www.the924.com |
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Cedric
Joined: 27 Aug 2004 Posts: 2608 Location: Sweden
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Posted: Thu Apr 30, 2020 6:43 pm Post subject: |
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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.
_________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
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morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
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Posted: Thu Apr 30, 2020 8:12 pm Post subject: |
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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 _________________ https://www.the924.com |
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Cedric
Joined: 27 Aug 2004 Posts: 2608 Location: Sweden
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Posted: Thu Apr 30, 2020 11:22 pm Post subject: |
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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. _________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
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gegge
Joined: 27 Jul 2007 Posts: 1124 Location: Sweden
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Posted: Fri May 01, 2020 4:40 am Post subject: |
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I still donīt 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! _________________ 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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Cedric
Joined: 27 Aug 2004 Posts: 2608 Location: Sweden
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Posted: Fri May 01, 2020 4:52 am Post subject: |
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gegge wrote: | I still donīt 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 _________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
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morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
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Posted: Fri May 01, 2020 6:20 am Post subject: |
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dunno why carbs..but they also ditched the cam cover _________________ https://www.the924.com |
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joewest
Joined: 06 Oct 2005 Posts: 234 Location: Portland, OR
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Posted: Sat May 02, 2020 3:42 am Post subject: |
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Awesome upgrade! _________________ '79 924 Supercharged / Track Prepared
'80 931 Daily Driver - Sold
"The number of posts in my profile may represent the number of times I have screwed something up...and admitted it here." |
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morghen
Joined: 21 Jan 2005 Posts: 8879 Location: Romania
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Posted: Sat May 02, 2020 6:20 am Post subject: |
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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.
_________________ https://www.the924.com |
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Fasteddie313
Joined: 29 Sep 2013 Posts: 2596 Location: MI
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Posted: Sat May 02, 2020 8:35 am Post subject: |
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It does sound pretty quick.. _________________ 80 Turbo - Slightly Modified |
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Sndtech
Joined: 23 Apr 2013 Posts: 59 Location: New York
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Posted: Sat May 02, 2020 3:44 pm Post subject: |
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Real sweet .. sounds great and seems very responsive with instant power.. _________________ Manny-
1977 924 Red "Wheeler Dealer Car" | 1977 924 Martini | 1979 Sebring |1979 924 N/A Dolomite Grey | 1980 924 N/A Minerva Blue |
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Dutch924-racer
Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands
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Posted: Sun May 03, 2020 3:24 pm Post subject: |
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Cool video! _________________ 937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller |
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Euro924S2
Joined: 06 Mar 2008 Posts: 215 Location: UK
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Posted: Mon May 04, 2020 10:44 pm Post subject: |
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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? _________________ 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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Cedric
Joined: 27 Aug 2004 Posts: 2608 Location: Sweden
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Posted: Mon May 04, 2020 11:05 pm Post subject: |
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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 _________________ 1980 924 Turbo
www.instagram.com/garagecedric/ |
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