Brake Booster Vacuum for a Turbo Install

[2xWhiskey]

Hi all,

 

Yeah I'm a newb in general (the forum and working on cars).  Anyways I bought a 71 510 wagon that already had a KA24E swap done.  After driving it a couple a couple of times,my friend (my auto knowledge source) and I started to take a real close look at the work done.  Needless to say, one thing led to another and I decided to throw a turbo on it.

 

This 510 has a vacuum assisted brake master cylinder that gets its vacuum from the intake manifold.  Since I'm installing the turbo, this will cause the manifold pressure to go from negative to positive while under boost (so goes my theory goes).  

 

Do I need to rig a standalone vacuum source like from an electric vacuum pump, or will a simple check valve addition work?

 

My line of thinking is that when under boost I don't want positive pressure on the master, making it harder to actuate the brakes(and the diaphragm was designed to work with vacuum).  But I do realize that if I'm under boost, I wouldn't be wanting to actuate the brakes at that point in time anyway.

 

Thanks for your time, and let the hazing begin!

[datzenmike]

First of all you are not likely to be boosting while you are braking. Second, there is a one way valve (or should be) in the brake booster line. It allows air to be sucked out of the booster but you can't push air into it. In a properly running booster there is enough vacuum stored for at least one good stab of the brakes, enough for the BOV to begin working and manifold vacuum to rise..

[2xWhiskey]

Thanks for the informative reply.  It will be nice to know this is a nonissue.

 

I've been racking my brain over it the past few days and was wondering why a couple was used inline with the brake booster vacuum line.  I'm pretty sure you've just verified it as a one-way check valve.

 

Any thoughts on adding a vacuum reservoir for a safety margin?  I'm thinking it's fine as is, at least until I get a feel for it.