OK, so whats the best thing to fit to the s4 then ?
done a bit of searching around, and dump valves are a no no, and BOV's are a yes yes, but dont make a much noise.
is this right ?
can anyone describe the noise to me ?
Dump Valve, BOVs, etc
Olly,
I believe that 'dump valves' and 'BOVs' (blow-off valves) are the same thing: They release the pressurised air to atmosphere when the throttle closes. This is what makes the noise - a quick hiss of air, similar to that when the nozzle on a tyre is opened.
The S4 (2.7 biturbo) relies on recirculation of the air rather than release to atmosphere. So the 3-port valves are know as DVs (diverter valves) or 'recirculation valves'. Because the air is simply fed back into the turbo intakes, the only noise is that due to the pressure drop across the valve. This does make a hiss, but rather quiet so that it can only be heard when driving slowly with the windows open.
I believe that 'dump valves' and 'BOVs' (blow-off valves) are the same thing: They release the pressurised air to atmosphere when the throttle closes. This is what makes the noise - a quick hiss of air, similar to that when the nozzle on a tyre is opened.
The S4 (2.7 biturbo) relies on recirculation of the air rather than release to atmosphere. So the 3-port valves are know as DVs (diverter valves) or 'recirculation valves'. Because the air is simply fed back into the turbo intakes, the only noise is that due to the pressure drop across the valve. This does make a hiss, but rather quiet so that it can only be heard when driving slowly with the windows open.
2001 Silver S4 Avant
AmD remap, APR R1 DVs, APR bipipe, Full Miltek exhaust
H&R coilovers, AWE DTS, Porsche front brakes, Short-shifter, 18" RS4 replicas
Defi-HUD boost gauge / turbo-timer (with afterrun pump modification), Phatbox
AmD remap, APR R1 DVs, APR bipipe, Full Miltek exhaust
H&R coilovers, AWE DTS, Porsche front brakes, Short-shifter, 18" RS4 replicas
Defi-HUD boost gauge / turbo-timer (with afterrun pump modification), Phatbox
No such sound for the S4. If you love it so much, your only choice is to buy an aftermarket unit which simulates the sound (yes you can buy them).
2001 Silver S4 Avant
AmD remap, APR R1 DVs, APR bipipe, Full Miltek exhaust
H&R coilovers, AWE DTS, Porsche front brakes, Short-shifter, 18" RS4 replicas
Defi-HUD boost gauge / turbo-timer (with afterrun pump modification), Phatbox
AmD remap, APR R1 DVs, APR bipipe, Full Miltek exhaust
H&R coilovers, AWE DTS, Porsche front brakes, Short-shifter, 18" RS4 replicas
Defi-HUD boost gauge / turbo-timer (with afterrun pump modification), Phatbox
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