vacuum sources for turboed engines ??

steptoe · Post by **steptoe** » Mon Mar 27, 2006 4:06 pm

In planning my turbo conversion, my thinking has hit a stumbling block

If the turbo pressurises the inlet manifold at times vacuum operated bits need consideration don't they ?

Firstly , vacuum advance is most likely disconnected, so no worries.

vacuum brake booster holds vacuum for one operation at least, and the Subaru vacuum operated heater controls...

And what do you do to protect these from boost pressure popping things off or undoing their intended functions.

Another vacuum reliant item on me Brumby is cruise control

The LPG safety cut out is also vacuuum operated, so an electric box will take care of the fuel supply

My limited experience with turbos is with Diesels and they don't have manifold vacuum at all , rather a vac pump on the back of the alternator or completely separate so those conversions don't need any attention.

So what do you do with petrol or gas converting to turbo ??

Craigus · Post by **Craigus** » Mon Mar 27, 2006 5:49 pm

The brake booster hose in turbo cars has a one way valve in the line. You would normally be off the throttle if seriously braking anyway, so there'll be plenty of vacuum in that state.

I'm not sure what happens with the vacuum powered vents and stuff - I haven't found a valve in the system, but maybe there is one.

The distributor in the older stlye cars has both advance and retard, so there's no issue there.

tim_81coupe · Post by **tim_81coupe** » Mon Mar 27, 2006 6:25 pm

As Craigus said, one way valves for your heater controls and brake booster. You will need to add the valve for the vents.

You could also hook vacuum items up pre-turbo, plenty of vacuum there when the revs get up, not so much down low though.

The PCV system on my EJ20G runs off pre-turbo suction.

PeeJay · Post by **PeeJay** » Mon Mar 27, 2006 8:45 pm

One way valve in the brake booster line is a must, it's scary when the brakes take 1.5 secs to activate 8O

As for the vacume lines, just get the big white thing (name?) off an RX turbo. It seems to be another one way valve of some sort.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Tue Mar 28, 2006 12:41 am

You could always isolate the vacuum systems (all but the brake booster) and use a liberty cruise control vacuum pump, i have one of those controlling the cruise system on my RX and another on Dads RX controlling all the vacuum operated bits except the brakes

steptoe · Post by **steptoe** » Wed Mar 29, 2006 12:56 pm

yeh , thanks, always noticed boosters hold a vacuum well after engine switched off so that no worry

so one way valves need thought and attention for the other bits and subie made a vacuum pump, belt driven I bet

if as a last resort I could hook up a mouth piece to suck on

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Wed Mar 29, 2006 4:24 pm

The Vac pump for the Liberty cruise control is electric.

steptoe · Post by **steptoe** » Thu Mar 30, 2006 1:23 pm

thanks swk, so it won't be found engine mounted. for trivia sake , know where it lives ?

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Thu Mar 30, 2006 7:06 pm

It lives at the rear of the engine bay bolted to the firewall on the LH side just under the cruise control throttle cable puller. You will need to supply power to 3 wires and then earth one to make the pump operate and pull a constant vacuum.

steptoe · Post by **steptoe** » Mon Apr 03, 2006 1:35 pm

Ok , thanks