Guys I've been wondering about something as I sometimes do. I asked my mate who knows more about cars but he could not explain this either

 

There are these vacuum lines coming from the balance bar to the clutch and brake pedal boosters and no doubt other places too.

 

But where does the vacuum actually come from?

 

From my understanding of physics (OK I only did A level) if I have two turbos forcing air into the plenum at 9PSI (or even 19PSI with my boost controller) or maybe even more, then surely the plenum is gonna be full of compressed air, not a lack of it (i.e. a vacuum)...... isn't it?

 

Does that makes sense?

 

Rich

You only create positive pressure or boost over a certain rpm. Roughly 3500k for a stockish car, obviously when you change gear come off boost etcs vacuum is recreated and stored there by the one way valve. Off boost the car produces roughly 7-9psi of vacuum pressure. Watch your boost gauge swing negative to positive whilst driving.

What does people boost gauge show when idling mine is 20vac is this to high my pulsar showed about 9in the vac?

Z idles at around neg 9psi but that's all the numbers you get. Sure the pulsar is reading in psi not hmgm or what ever that jap measurement is.

I meant the pulsar shoed -9 vaccum but my zed reads -20 vacuum I thought this was a little high

sounds normal m8 .. Vac -14>20 is right

Edited August 23, 201312 yr by MarkDerby

The zeds stock boost gauge doesn't read upto 20 psi mate.

sounds normal m8 .. Vac -14>20 is right

 

Cool just thought I'd check

 

Z32 bolt I've got an aftermarket boost gauge

Well that would explain it lol.