V8_SPANKER

diverter valve...a blow off valve...and a bypass valve?
thanks

frank@AMS

first there were turbo cars without any dump valves

excess pressure built up and backed into the turbo, whenever the throttle plate closed.

this back pressure, slowed down the turbo(s) and increased lag time on throttle re-opening.

then came atmospheric dump valves, which solved that issue, by dumping excess pressure overboard between shifts

but as Mass airflow meters became common, wasting all that carefully measured air became a draw-back

so the Diverter or Bypass or Plumb-back, design came about...instead of throwing away metered amounts of air.

It dumps the excess boost back into the airbox just behind the air meter or MAF and thereby retains the air:fuel ratio and long-term fuel trim..carefully learned by the ECU.

so is simplistic terms, it's an evolutionary model

NO valve(s) older turbo cars (and Rally cars)
.
.
Atmo or Blow-off valves
.
.
Bypass/Recirc/Diverter/Plumb-back Valves

Rory

are both used to described a gate located in front of the throttle body used to release excess pressure that builds when the throttle plate closes suddenly; the gate reroutes this air to the intake, after the MAS. As has been pointed out, though, the later can be used to describe a gate that dumps to atmosphere.

Rory

PhoenixGTS

being plumbed back in or vented to atmosphere.