I have a feeling that fitting a BOV will cause issues, as you are letting air escape that the MAF has registered and fuelled for. Possibly you may get an expected air quantity fault, or maybe the MAP sensor will see the pressure drop faster than expected and increase the VNT more to compensate, perhaps causing overboost when you come back on the throttle.
Also, I can't really see how it's going to
make much of a noise, as when you take your foot off the throttle pedal there is no butterfly closing. On a petrol turbo a blow off valve releases air that is under pressure, effectively trapped between the turbo and the closed throttle butterfly, to stop this build up of air stalling the compressor. On a diesel, there is no throttle butterfly to close, so the engine simply continues to take in the air, but fuel is not added, and the turbo decelerates. The lack of trapped air means its not really going to 'whoosh' when the BOV is opened, it'll probably be a bit more of a hiss than a whoosh.
Also, most petrol turbo BOVs are opened by vacuum, when the throttle butterfly closes, this causes a vacuum in the inlet manifold, this vacuum opens the BOV. On a diesel there is no vacuum in the inlet manifold, because there is no throttle butterfly, so I'm not sure what you would use to provide vacuum to the BOV when you come off the throttle. Maybe you can get an electronic one that operates off throttle position. You can buy ones that aren't even connected to the induction system, they just make the noise electronically when certain conditions are met.
- UK's leading independent Alfa Romeo specialist with branches in Bedfordshire, Cumbria & Dorset
Wizard Exhaust systems available here
Tel: 01768 879 171