924Board.org

gegge · Joined: 27 Jul 2007 Posts: 1124 Location: Sweden

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

morghen · Joined: 21 Jan 2005 Posts: 8879 Location: Romania

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

Cedric · Joined: 27 Aug 2004 Posts: 2608 Location: Sweden

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/

morghen · Joined: 21 Jan 2005 Posts: 8879 Location: Romania

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

Cedric · Joined: 27 Aug 2004 Posts: 2608 Location: Sweden

gegge · Joined: 27 Jul 2007 Posts: 1124 Location: Sweden

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!
_________________
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

Cedric · Joined: 27 Aug 2004 Posts: 2608 Location: Sweden

morghen · Joined: 21 Jan 2005 Posts: 8879 Location: Romania

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

_________________
https://www.the924.com

joewest · Joined: 06 Oct 2005 Posts: 234 Location: Portland, OR

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."

morghen · Joined: 21 Jan 2005 Posts: 8879 Location: Romania

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

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

It does sound pretty quick..
_________________
80 Turbo - Slightly Modified

Sndtech · Joined: 23 Apr 2013 Posts: 59 Location: New York

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

Dutch924-racer · Joined: 23 Jul 2007 Posts: 1077 Location: The Netherlands

Cool video!
_________________
937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller

Euro924S2 · Joined: 06 Mar 2008 Posts: 215 Location: UK

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

Cedric · Joined: 27 Aug 2004 Posts: 2608 Location: Sweden