As I am finishing up my supercharged 944, I am puzzled by one thing. What do I have to do to the vacuum system to maintain it during boost? Can I run all the vacuum lines to the same locations or do I need to re-route them?
The FPR and brake booster have vacuum lines and there's some other small ones, am I missing something here?
Copy the vacuum routing used in the 944 turbo. Basically you'll want the booster and hvac on a one-way valve.
The FPR line should go to the manifold after the blower, so its reading manifold pressure- no check valves. Purge lines and other engine control type stuff I would leave in its original location. Vacuum for brakes and heater controls (I think 944s use vacuum doors in the heater)and that sort of stuff needs to come from the manifold, and there should already be a oneway valve in the line, but it may not work as well as it did when it was new. You may need a storage tank to maintain enough vacuum to the brakes and heater for climbing hills, high speed cruising or hooning, and if you are an uber-hooner, you may decide to add some sort of vacuum pump to keep the brake booster happy. If its like everything else of that vintage, the heater will default to defrost when the vacuum drops low, so that's a good sign to help decide what you need to add.
It seems pretty basic but I'll add this anyway: you might need to clamp all the hoses to keep them from popping off under boost.
Good info, thanks guys! The 944 apparently comes with a vacuum reservoir already as well, which should help.
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