How to get vacuum for brake booster with large cam?

[granatl]

[Although this isn't my Buick, it's a very similar setup]
I have a pretty aggressive cam in my turbo Camaro. Most of the time, the manifold draws enough vacuum to give me power brakes, but most isn't good enough! So I installed an electric vacuum pump instead and blocked off the manifold line.

I'd like to T the two of them together, so that the pump has to work far less. Is there some way to assemble this so that
1. Boost isn't blown into the brake booster
2. The electric pump isn't forever trying to draw vacuum from the manifold.

Here a link to the vacuum pump: http://www.summitracing.com/parts/cca-5500

 

[Joeld]

how about hose from manifold then check valve than t then you have pump feeding t and the t terminates to booster?

maybe i am missing something?

joel

 

[87-WE2]

A very detailed (and professional) drawing of what we did to my brother's boosted Camaro. Sorry - no pictures.

Explanation:
At idle and cruse, manifold draws vacuum. Vacuum flows right to left in the diagram from booster, thru tee, thru check valve, thru tee, back to source.

During boost, pressure flows left to right in the diagram from manifold, to tee, and closes check valve. Pressure activates the hobbs switch and vacuum pump. Vacuum pump draws vacuum from booster on right, thru tee, and also clears any possible boost that gets by the check valve.

I didn't really like his idea because I didn't like the idea of trusting my brakes (and life) to a $2 check valve. But it works. And my $2 check valve works on my vacuum brake setup on the GN.

Just an idea.

 

[TexasT]

There was a thread where a member is using a vacuum pump from a Volvo I think. He mounted two to be redundant in case of failure. He thought it pretty nifty. He mounted them behind the headlight I think.

I'll see if I can find it.

 

[davelostmissing]

A quick internet peruse shows me a kit using that 5500 pump which also includes a switch that (quote)
:Operates when vacuum drops below 18 inches and turns off when over 22 inches (unquote)
http://www.amazon.com/COMP-Cams-5500-Electric-Vacuum/dp/B001O0685G

That would take care of only running the pump as required, still need the checkvalves similar to above...

 

[granatl]

Thanks for the info guys. I just can't fathom how to block boost and vacuum, but maybe after I study the diagram a while, I'll get it.

Yes, the 5500 includes a switch to turn it off, and does work. But if the manifold is drawing (say) 14" of vacuum and the pump wants to see 22", it'll forever run.

 

[davelostmissing]

So you are saying you are happy with the quality of the brakes at 14 inches of vacuum? Then you need a switch with different setpoints.

 

[87-WE2]

Thanks for the info guys. I just can't fathom how to block boost and vacuum, but maybe after I study the diagram a while, I'll get it.

The check valve prevents boost from going past it; it only opens when it's being sucked (giggity).