Maybe Im stupid But How does a GN pull vacuum from the upper?

[Conan56]

When underboost The Gn's Doghouse becomes pressurized by the boost created by the turbo
At this point (Underboost) How does the Gn pull vacuum for the FP Reg and other Vacuum controlled items?>

Im asking this because I am currently working an a vehicle that used to be supercharged and Now Im converting it over to A turbo because it is much more efficient
The Car currently pulls vacuum From the Plenum (Supercharger inlet)
Now I plan to build an Intake Similar to the Gns Intake
And I plan to Blow Through the TB
before it was sucked though and then boost was created

I cant figure out where I should pull boost from now
Maybe before the turbo? on the intake?

I know the answer is prob pretty Obvious but I cant seem to figure it out

 

[strikeeagle]

Well, if you're talking the FPR, it uses the pressure in the doghouse, whether vacuum or boost, as a reference signal.

The FRP maintains the pressure difference between fuel pressure at the FPR inlet (i.e. the fuel pump discharge pressure minus any pressure losses between the fuel pump discharge and FPR inlet) and the reference pressure.

As the FPR is downstream of the fuel rail/injectors, it opens to decrease the pressure at the injector, and closes to increase it.

Thus the FPR is, in fact, a DIFFERENTIAL BACK PRESSURE regulator.

There is a similar "story" for all the other "gizmos" using "vacuum" at idle. For example, the PCV checks under boost, preventing the crankcase from pressurizing, and so on.

strike

 

[pacecarta]

on decell or at idle there is vacuum which is stored in a vacuum canister, on the 87 gn its a ball, there is a check valve in the line to the ball to hold the vac for operation of the cruise servo and the ventilation systems diaphrams

for vacuum brakes on the 89TTA or when converted over in the regal , the booster holds the vacuum in reserve with a check valve at the booster inlet.
the egr and vapor canister only needs to function at decell or light cruise and there is vaccuum present in the plenum when it is needed to operate those devices