Been a while since I updated this thread, just passed 202,000 miles and still running solid! So I ended up rebuilding the supercharger again with a new rotorpack from a Cobalt SS supercharger. The rotor blades were the exact same, but the bearing shafts on the new rotors were about 7 mm longer than the old rotors.
This meant the needle bearings in the back of the supercharger had to be recessed further down for the new rotors to work. So back to hacking everything up again... This is probably not the way to go about it, but I made do with the tools I had and about 8,000 miles later the supercharger is still running strong. I got a giant ass drill bit 1/64" smaller than the diameter of the bore where the needle bearings press into, and drilled the two holes a few mm deeper. When I reached the depth I needed, I then swept the holes by hand with a circular sanding bit on a Dremel until the bore of the holes got back to the press-fit tolerance. Miraculously I drilled the holes straight and the new bearings pressed in snug and now sit deep enough for the new rotors. And, everything still turned smooth! While I had the supercharger in pieces I removed the stock air temp sensor I had fitted in the manifold, and re-drilled and tapped the hole for an aftermarket air temp sensor that can go up to 300 ºF. I also replaced the shaft seal on the supercharger snout and reassembled the supercharger with a silicone sealer designed for gear oil (the red anaerobic stuff did not seal very well the first time around and I had multiple leaks).
I also made a custom air intake, which actually made a noticeable boost increase on the low end of the powerband. With the throttle pointing right up against the false firewall there's not a lot of room to wrap a 3" intake around so I used what's called a cobra head coupler.
For the intake temp sensor I welded a 2" x 1" x 1/2" piece of scrap aluminum to the intake tube and drilled a hole straight through it and drilled and tapped the M6 bolt thread. I also added a bung to thread a barb into for the PCV hose and I also welded in a bung for my cold side air temp sensor. One thing I noticed is that due to the location of the intake and temp sensor in this car, when the engine shuts off, all the heat from the downpipes rises up and heats up the intake tube. So when I start the car within an hour after I've been driving it, the intake air temp will read 120-150 ºF, which causes the AFR to be kind of lean until it figures out what's going on. I heat wrapped the aluminum intake tube too hoping it would help, but it still gets too hot. This also happened with the stock intake, so there's really not much that can be done, just a poor location for an intake temp sensor.
Now that I have cold and hot side aftermarket temp sensor locations, I was able to install my dual intake temp gauge in the driver side air vent.
For anyone that's curious, I typically see hot-side temps between 180 ºF and 220 ºF when I'm street racing at night and it's a little cooler, and the hottest I've seen it get was 240 ºF when I was hillclimbing this summer on a 100º day. I know I'm nearing the max temp you can be at with pump fuel, but I haven't had any issues yet. I'd like to be able to use an aftercooler like this:
https://mercracing.net/shop/ct-engin...charge-cooler/. I would either need to cast a new manifold or make an adapter plate that would probably be too big to work on this car... maybe one day.
Oh I almost forgot, here's a before and after of the supercharger boost... The rebuild got close to 2 psi of boost back just by having clean rotors.
It's hard to compare all the new data to the first log I made because it was freezing cold the first time I logged power, MAF, and timing after the initial install. Even though the boost is a lot higher, I only gained a few g/s of MAF, which is weird. I also found out that this car depends a lot on the intake temperature. The timing advance will change as much as 6-7 degrees based on the temps and the power and torque will change as much as 20 hp/tq depending on the time of year.
Some other things I've done since the last update are 18Z brakes, all 4 wheel bearings, B7 spindles then B5 S4 spindles, adjustable coilovers, had to replace the heater core, got 4 new S4 facelift doors (I've now replaced 7 panels on this car), black roof rails, and fixed the long cranking issue. I first had B7 aluminum spindles which did work, but they widened the track width just enough to destroy my inner axle boots in a few thousand miles. I'll probably go back to B7 spindles when I swap my spare 0A3 into the car because then I'll be using B7 axles and everything will be the right dimensions (since I hate the 01E and there's no way it lasts another season of street racing). To do B7 spindles all the control arms are the same except for the lower straight arm. The balljoint is a different size so you have to use a B7 control arm with a B5 shock bottom bushing. The ABS sensor also fits perfect in the bore if you use the same sleeve from your B5 spindles. Anyway, I'm just running B5 S4 spindles now and all the suspension parts and axles are happy.
For the doors everything was super quick except for the driver's door. The facelift doors have a new style door handle on the inside too, which created a problem because I still need to use the key in the door. There's no way to swap just the lock over to the newer door handle, so I had to cut up the two door handle/lock assemblies and bond them together. They're made of indium or tin and have a melting point under 400 ºF so they can't be fused or brazed, which means the only option is to use JB weld. It took a long ass time, but it worked and hasn't broken yet.
Heater core job wasn't too bad besides all my wiring I had to move around for the aftermarket gauges.
And the long cranking issue I've had for probably a year and a half now was the simplest thing ever. I guess AEM fuel pumps don't come with built-in check valves so I installed an in-line check valve with some standard 5/16" fuel line hose right above the outlet of the fuel pump and now the car starts up every time. This is the check valve I used:
https://www.highflowfuel.com/i-23908...-8mm-5-16.html.
And that's about everything I can think of since the last update!
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