As mentioned please do some research before attempting to fit one of these pointless devices but just incase you are too lazy here goes;
Lesson 1
DV's were invented for petrol cars, due to their nature petrol cars have a
throttle valve that regulates the amount of air entrained into the engine proportianate to your right foot.
Lesson 2
On petrol engines that employ a turbocharger to force more air into the engine and hence increase efficiency, can be subject to strain if the above mentioned
throttle valve is suddenly closed and the subsequent sudden increase in inlet pressure can actualy cause the turbine in the turbo to stall.
Lesson 3
This is where a DV comes into play, in an attempt to stop the turbo from stalling and creating even more strain on the already stressed componants of the turbo a pressure relief device was devised that would bleed off all this excess pressure thus preventing the said turbo from stalling.
Lesson 4
The DV operates by means of a diaphragm or pistion that is actuated on by a vacuum sourced from the inlet manifold of the engine this in turn opens the the DV and the subsequent charge is dumped to atmosphere (whooshy noise) or in the case of most VAG cars is recirculated back into the inlet system prior to the turbo.
Lesson 5
The vacuum pressure from the inlet manifold is generated when the
throttle valve is closed and the pistons in the engine try to suck more air into the engine which in combination with with the
throttle valve closed results in a vacuum being formed in the inlet manifold.
Lesson 6
If you have not already noticed by now the throttle valve plays a major part in the operation of any dump valve.
Now which componant do you think a diesel engine does not have ?
Wait for it
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You guesed it a
THROTTLE VALVE
Diesel engines continually draw air in and are controlled in speed and power by the amount of fuel injected into the cylinders. This is why a dump valve on a diesel engine serves no useful purpose other than to make a whooshing noise as the turbo is always free to spin no matter what throttle position you apply. Dump valves on diesels are electronically controlled hence why they are expensive but if you want to waste money on a pointless device then go ahead be my guest.
Alternatively why not record your mates DV and put it on a CD and play it at full volume down at the local chavs meet as this would have the same desired effect