oh right, thanks for the info, think I'll sit back on this one for a few months and see what develops.
Whats a DV valve? Its not one of things that makes your car sound like a chav-chariot is it?
Dump Valves are fitted to the engines of turbo chargged cars and sit between the turbo outlet and the throttle body. When transitioning from a boosted state to a closed throttle state (as in between shifts), due to inertia, the turbo continues to pressurize air, but the closed throttle prevents the compressed air from entering the engine. In this case the pressure exceeds the preset spring pressure in the dump valve and the excess pressure is bled off to atmosphere.
Even with a dump valve the compressed air acts as a brake on the turbo (slowing it down), because the pressure on the backside of the turbo is at a higher pressure than on the front side (and the air actually wants to flow through the turbo backwards).
The Chav type are atmospheric type, and the woosh you hear is the gases venting to atmosphere., the recirculating type fitted to VAG cars, doesn’t obviously make this noise
