924Board.org

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

That TB adapter looks nice, it will be nice to see everything sorted. Have you done alot of full throttle testing with this system?
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1980 924 Turbo
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morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

Testfit today, seems to fit well and installation is easy. So far so good.
I didn't figure out what size sealing o-ring I need so I can't run the car for now...but I'll get the right o-ring in the next couple of days and then I'll drive it. To be honest, I'm a bit disappointed that it can't run on the original rubber boot and while this does not scream modified (the kit will get black BOV valves) it still does not look factory enough to me.
Anyway, since that factory look is now ticked off as failed, I think I'm going to do the SC outlet tube in the same fashion as this last part I made.
At least that will make it look more consistent and also give a bit more flexibility for tolerances in the charge tract.

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kondzi · Joined: 02 Jul 2018 Posts: 485 Location: Poland/EU

Cool 3D prints. I'm not fully happy with the strength of 3D prints though in general, but PETG is a great material for car applications IMHO.
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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)

morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

The devil is always in the details, depending how you design the geometry...use the process and the materials combined with the material properties and post-treatment....you can extend their range of functionality a bit.
I found that PETG and ASA are cost effective materials that can do some work in the engine bay. ABS as well but that is harder to print and not really worth it over ASA for example.
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Sndtech · Joined: 23 Apr 2013 Posts: 59 Location: New York

Any updates on supercharger kit progress ? Looking forward to hearing more
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Manny-
1977 924 Red "Wheeler Dealer Car" | 1977 924 Martini | 1979 Sebring |1979 924 N/A Dolomite Grey | 1980 924 N/A Minerva Blue

morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

Hey Manny, good to hear from you.
Basically I'm not done with the kit yet but its not too far from being ready.
I could already send some out if I wanted as everything has held up well so far but I still have to take care of the crank ventilation, do some more testing and get the whole thing on a dyno.

Quick update on this project.
A lot of ugly weather lately makes me want to stay in the house rather than tinker with this car, also I've been quite busy at the end of last year and beginning of this one to finish my Cayman engine rebuild project.
I've done the new TB tube and I have the first wrapped prototype ready to be tested on the car but I'm missing a securing bracket which you can see the Fusion 360 sketch below in the picture. That will be a sheet metal part keeping the TB charge tube in place.
Also, a friend of mine has a 3 axis CNC machine and although the initial plan was to water jet cut the brackets out of steel and weld them in place using jigs, since I have access to this CNC machine I'll just do them out of Aluminium.
I linked a YouTube video of a bracket milling simulation. I hope to do the first bracket cut next week.

The 924 supercharger kit currently consists of the following part categories:

1. brakets and mounts for the supercharger
2. crank pulley, tensioner and belt.
3. all required hardware, nuts and bolts.
4. inlet and outlet tubes to and from the supercharger
5. complementary blow off valve and silicone hoses and clamps
6. silicone vacuum hoses and vacuum T pieces
7. new airbox bottom surface (also serves as cutting template for your existing airbox)
8. fuel line adaptor (fitting and tightening the original one is difficult with the supercharger in the way)
9. instructions on how to fit all that to the 924 as well as how to lightly modify the supercharger (two of its original mounts need to be sawed off as they can touch the 924 brake lines and impede assembly of the SC)

The kit does not include the supercharger and its original recirculation valve.
Whats missing here is the crank case ventilation system, currently mine is just hanging under the car but I'll need to make brackets and hoses for a catch can. Normally this gets connected to the vacuum side of the intake..but I don't want to run all that stuff trough the supercharger or the CIS plate.

CNC milling simulation for one of the brackets:
https://youtu.be/SJL7t4G4whA

TB charge tube securing bracket:

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Juho · Joined: 03 Oct 2018 Posts: 377 Location: Finland

Do you have picture of the crank pulley? willl it allow to run trigger wheel?

morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

Have a look on the first page of this thread, thats the only crank pulley picture i have. It has a flat front so in theory it could carry a toothed gear for triggering. I’d take the signal from the cam if i were doing an efi conversion, seen some clever ideas lately.
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Juho · Joined: 03 Oct 2018 Posts: 377 Location: Finland

When you think you will start selling the kit?

jacobroufa · Joined: 18 Nov 2016 Posts: 529 Location: Belvidere, IL

Love seeing progress on this. I have got a line on a charger for a good price locally for when you've got a kit together..

Since you've added the kit detail I'm curious about modifications to the car since this was originally posited as a fully bolt-on kit. Is the airbox the only original item that has to be modified here?

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I was talking about this idea with a friend of mine, knowing less about your implementation than I'd like, and he asked me why the throttle body was not relocated to the front of the supercharger, to avoid the pressure drop when throttle is opened and to keep the charger from working when it doesn't need to (building pressure against a closed throttle plate vs in vacuum). Doing some research it looks like this is common wisdom for supercharging in modern cars (including the Mini the blower was sourced from). It seems like a big rabbit hole for the 924 though... I'm guessing the bov next to the throttle compensates for this in your setup?

I'm just curious to know more about the thought behind the design process and about how the pressures might affect our stock system.

If designed similarly to the Mini, could we use a stock intake manifold, cut off the plenum and adapt the outlet of an intercooler to the runners? Then inlet of intercooler to outlet of charger? This would make a pretty compact packaging on the side of the block, potentially. Then place the throttle body between the supercharger inlet and the fuel distributor, adapting throttle cable as necessary.. The sacrifice here would be an intake manifold and throttle cable.. seems like the coupling between everything could be made simpler, and with a liquid intercooler core could provide more boost than you were aiming for.
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1980 Porsche 931
1981 Porsche 924 Weissach

morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

I've done a lot of thinking before and during the development of this kit.
I wanted something that would make the car more fun to drive but not look modified when you looked at the engine(failed that one since i cant use the oem tb boot and some pipes are visible).
I also wanted something that can be installed in a few hours and taken off if needed or wanted.
The idea was that it should be bolt on as much as possible, fully reversible so no permanent mods on big parts like the intake...no oem parts relocation as much as possible...use as many oem parts and as few non oem parts as possible.
If you start thinking about cutting the manifold..its a rabbit hole...one thing will imply another and in no-time you'll be redesigning the whole engine bay...and more.
So the aim of this kit is for any guy with a set of spanners in his garage to fit this thing to his 924 with no advanced mechanical skills needed to install.

For my solution, you need to cut the bottom end of the airbox and glue in a replacement that i made in fiberglass...and elongate one of its mounting holes...this is to clear the top of the supercharger.
This plastic part can be replaced in a few minutes if one would want that, so while it is a permanent mod on one of the parts, it is not visible and its a compromise i am willing to make.
Also the metering head rubber boot has a port that normally goes to the brake booster, that one must be plugged, i cutted mine off and plugged it...and the oil dip stick must be bent to clear the supercharger intake pipes.
I went for subtle and easy mods here and there to make room for this system instead of redesigning the whole engine bay.
This approach is clearly not for everyone as some would rather take everything off and throw efi and what not at their cars.
I respect that, but this is a different thing. This is...if you like, making the most with as little as possible in the least amount of time...while keeping the factory look as close as possible.

In regards to the arangement of supercharger before TB, the main reason is as i stated above, to avoid relocation and further mods that would imply another wave of mods and so on.
However, as you observed, this arangement is the same as found on the Mini Cooper and other aftermarket solutions for the MX5 for example.
The benefit is "electric" pedal response, instant boost as soon as you touch the pedal...also, using a pneumatic recirculation valve instead of cable operated one adds to the "electric" feel and while i dont have a dyno sheet yet, i bet it enlarges the area under the torque line by adding a lot of torque at lower rpm and probably increasing the peak torque as well.
So, whats not clearly visible form the pictures i posted is that i use a recirculation valve that comes original with that particular supercharger to mitigate the pressures between the supercharger and the TB when the TB is shut.
The blow off valve that you see in the last picture is both a refinement and a safety net if the oem valve should fail at one point in the future.
I used a pink one because i had one around..but kit will come with black ones...and i'll paint mine black as well soon

In regards to more power, more boost.
The car is so much fun to drive compared to without this system on that i dont really feel the need to add more power.
I would like to push it a bit more, but i would have to do severe compromises to my initial goals and/or higher the risks...adding an intercooler to this setup and keeping CIS in place is not something i could immagine...if i could...i would have added a small intercooler from the start...but there simply isnt enough space.
So if more boost is desired, meth/water injection can be a solution...although experience rounded up from the community does not favor this aspect.
Air/water intercooling is out of the question, i consider that as very complicated to design and manufacture with risks that outweigh the benefits.
I've seen others fail and struggle, i know precisely why i dont want to do it.
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jacobroufa · Joined: 18 Nov 2016 Posts: 529 Location: Belvidere, IL

Excellent! I really appreciate the extra details, and think you're spot on for not wanting to try too much modification there. Just thinking about it for a short while caused my head to spin. I just felt like I had to get a sanity check so thanks for humoring me...

I am really looking forward to feeling this for myself -- it sounds like you've conquered the lack of bottom end in our cars.

I just snagged that supercharger locally, so you've got another tester as soon as you're ready!
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1980 Porsche 931
1981 Porsche 924 Weissach

morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

Finally had a drive with the 3D printed TB piece on and the additional dump valve.
The additional dump valve makes cruising at high speeds smooth as it should be and now the acceleration is easier to modulate. Quite pleased with this improvement.
The attachment method to the TB however, needs to be improved.
I'll do one more design loop on this part while I prepare the others for production.

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https://www.the924.com

morghen · Joined: 21 Jan 2005 Posts: 8880 Location: Romania

Part of the kit in place as on the 924 engine.
Will do a video with all the parts including the dump valve, all tubes and hoses, brackets, air box shroud and crank pulley.
Now to find a decent supplier that can do the CNC parts.

https://www.youtube.com/watch?v=-51cJWAS2QI

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

Looks very good! I think there will be many interested 924 owners when this is done.

I noticed that speed academy made some fiddling to get the driveability fixed on their supercharged Lexus, to calm it down a bit when coming on the throttle. It was fixed with a little restrictor in the line to the standard bypass valve to make it shut a bit slower. Is it anything you have tried?

https://youtu.be/Bh-Ka-jOBIg
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1980 924 Turbo
www.instagram.com/garagecedric/