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Old 08-08-2004, 03:43 AM   #24
Scooby Guru
Member#: 64673
Join Date: Jun 2004
Chapter/Region: NWIC
Location: portland
1990 Legacy wagon
goes 12.387 @ 116.5


The supercharger is clutch driven so you cant change it. this is because the magnetic part is inside the pulley, so the pulley diameter is dictated by the magnetic part of the pulley. I did see a smaller pulley made for the mercedes superchargers but A- they were like $500 and B- may not have been for this particular supercharger.

My fears for making a bigger crank pulley would be A- an exploding crank pulley. B- Overdriving the alternator and power steering. Solutions for this would be to just get smaller alternator and powersteering pulley. Those I can personally make. It is the larger crank pulley that my lathe is too small for.

I dont have ac, so dont have to worry about that. I have considered getting rid of the powersteering too. We shall see.

Ok , now a rough performance review.

It definately works. If you floor it it first and then flick the switch at 4000k, the car jerks forward like you hit nitrous. This was just a test though, obviously you want it on from 0 to 6500 rpm.

If you go to this site,

you can see the compressor map. While not the same as my supercharger, I suspect it is very close. So basically, as the rpms rise, so does the power, with no spike, it just goes faster and faster.

I suspect that right now I have a bout a 10 to 20 hp increase. Not much but something and it is noticable. With the larger pulley, it will be worth all the time.

Now the noise. LOUD. Since I dont have an integrated throttle bypass valve (not the BOV) all air must come through the compressor. At this point I also have a suck ass BOV, this leaks I think even at boost, and when I let off the throttle, it sounds like a very large angry farting BOV.

The compressor noise itself is also very loud but cool sounding.

The compressor at this stage is activated by an on/off switch located on the dash. This is so that I can activate the supercharger as long as the rpm is below 3500 rpm. My fear of having the supercharger come on only at WOT, is that I have heard of belts snapping when jerked into action too hard. I still need to do some fine tuning obviously.
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