dump valve

[General Baxter]

stupid question but what are the mechanicals of one

i know they let boost pressure out, but how ?

[mowgli]

big rubber flap & a spring.... when the pressure gets too much, they let some out

[Jack]

^ not exactly, thats more like a wastegate.

Its basically a vacuum valve that opens when the throttle is closed.

It sits between the charger and inlet (I've seen one fitted between the air filter and charger before, LOL). Its activated by a vacuum hose which goes behind the throttle plate.

The theory is, when the throttle is closed, the charger is still creating pressure which has nowhere to go (on a screw or rotary supercharger, it will break the screw, on a turbocharger it causes turbine stall). The DV uses the vacuum behind the closed throttle plate to open the main valve and release the pressure to stop it damaging the turbo or supercharger, hence also called Relief or Release Valves as well.

DTA DVs just dump the boost out to atmosphere. Rercirculating DVs drop it back in between the turbo and air filter (so are quieter).

Bear in mind a DV won't prevent overboost (so it won't activate when "pressure gets too much"), it will only activate on throttle closed.

[General Baxter]

are they adjustable ?

as on tick over i need my 10psi to go somewhere lol

[mowgli]

what i described is what baxter needs... I live only a couple of miles from him. who knows how big the crater will be when it goes.....

[Jack]

I did this diagram when explaining it to Mike:

http://i13.photobucket.com/albums/a266/razorjack/Misc/dv_diag.gif

On a supercharger technically there shouldn't be any disadvantage, as it won't lag like a turbocharger.

[edit] Baxter Id guess you need something like an EBC that controls the DV.

[burgo]

baxter just needs proper management that can handle the 10psi on tick over

[General Baxter]

baxter just needs proper management that can handle the 10psi on tick over

no you dumb ass,

i dont want the pressure going back thru the charger when i close the throttle, nothing todo with managment lol