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Old 07-06-2006, 01:25 AM   #5 (permalink)
CpuZapper
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rspidydude,
Unless you're just setting up your SC to be on a toggle (I still don't know why you'd want to do that), it is a very bad idea to lock your SC into an engaged state. It will severly reduce the life of your supercharger, and will also very rapidly heat-soak your entire intake tract. The computer already manages the supercharger quite effectively. There is also an Air Bypass Valve (kinda like a recirculated BOV) that routes air around the SC when it is shut off. Basically, any time the computer estimates (since there is no vacuum sensor) that there is only about 8" of vacuum, it will engage the SC and shut the ABV. The SC will be on from then, until it sees about 10" of vacuum for more than 5 seconds when it will disengage and open the ABV. This is so it doesn't disengage between shifts.

Also, once you get an overdrive pulley, you will need to do the ABV mod. The ABV will act as an overboost safety device so that if it goes over 8 psi, it will open a little, and vent the boost back before the SC. Something interesting is that the throttle body is before the SC and intercooler, which is why having the SC on while cruising is not a good or efficient idea.

Just to give you an idea of the temperatures (from the MK1 Archive): The supercharger adds heat to the intake charge both by conduction of housing heat since the supercharger is bolted onto the engine and also by pressurizing the intake charge. With the bypass valve open and the supercharger disengaged the intake system raises the intake charge temperature by about 30 degrees F once everything is up to operating temperature. Running under full boost with an outside air temperature of 50 degrees F the air temperature of the SC outlet can get as high as 270 degrees.

When you put the new pulley on, you will need to change the vacuum lines to the ABV. Here are some images to describe:

Before:


After:

Last edited by CpuZapper; 04-17-2007 at 01:28 AM..
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