vacum on boost?
Turbo Mini Forums

ok so possibly the dozyest question i have ever asked a forum but it is just something i dont know

when a car is on boost where does the vacum come from to run a brake servo or does it function as well?

please be nice is this just a mega thick question?

well how many times do you brake on boost??
i think there is a one way valve in the servo pipe however youll only be braking when off throttle so the servo should never seee boost ..
Please feel free to correct me if im wrong..

Yes when braking you will be off boost normally so servo will see vacuum to assist your pedal effort. However if like me you like to left foot brake then you will find left foot braking while on boost will cause a hard brake pedal. Easy way round this if it bothers you is to junk the servo and use a non-assisted master cylinder.

yes vacuum comes off boost, same vacuum that ttssshhh the dump valve, servo pipe shud have its one way valve close to the inlet as poss so to create a short pipe to vacuum rather than a long one,

sorry forgot the most relevant element to me i am running a super charger will i still see a vacum when decelerating?

Yes you will so long as it's plumbed up correctly.

Strictly speekings its not a true vacum. When you close the throttle the butterfly closes, the engine removes air from behind it in the inlet manifold etc. so the result is less pressure in the inlet system than normal atmospheric pressure. So it works on super charger the same as a turbo setup, blow through or suck through.

cool thanks for the info

your servo has a reserve of about 3-5 stabs at the pedal, so it should be ok even on left foot braking :)

alex

AlexF

do the peeps on this board recon a servo is worthwhile

I run one :)

metro 4 pots on vented disks with mintex 1144 pads on dts disks with dot 4 fluid

trackday use only!

alex

AlexF

i ditched mine, i never liked it, plus i'd snapped a mounting bolt for it so the MOT man always gave me a dodgy look if he noticed it. it does take up a lot fo room aswell, makes it even harder to get my fat hands in the engine bay.