Supercharger Boost/Vacuum ??

[FordNut]

Help me understand something about superchargers, please....

The power brake booster works on vacuum, as do some other accessories (heater duct doors and such). When you go into boost, what happens to those accessories? Is there a check valve in the supply lines to keep the reservoirs from losing vacuum? Is there one added with the supercharger kit? For example, if someone were cruising for a long time under boost, would these devices eventually stop working? Anyone considered adding an electric vacuum pump like the ones in turbo Diesel trucks?

[Wires]

Most non-forced induction cars have check valves for the brake booster, but judging from the manifold pressure gauge in my turbocharged car (no FI for my Marauder :( ) as soon as one releases the throttle, the manifold is back to vacuum. I believe a good supercharger setup would operate the same way - no throttle, no boost.


But, the MM has vacuum operated climate controls, etc. Do those not work when driving with positive manifold pressure, or is there some sort of vacuum resivoir/check valve for this system too?

That's a good question. It should be educational to see what the guys with FI have to say about it.

[carfixer]

On all Ford built cars, the brake booster has a vacuum check valve at the end of the hose where it goes into the booster. The A/C system has a check valve and a vacuum resevoir. The resevoir is located on the left fender well.
Stuff like the evaporative emissions system and EGR, which are vacuum operated, are turned off during heavy load situations so no check valve needed for those items.