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silly topic

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edy:
did you no they are also illigal, BUT the fuzz have to see it in action, wich is imposible without driving, even then they cant actually see it, hence why you will never get stopped for it  :D  

i think it is the noise.

paradigm shift:
Ok, a dump valve (or blow-off valve) is simply designed to release the boost pressure in the intake when the throttle is closed. The theory is that the air has to escape somewhere and if it can't go through the throttle body it'll flow back through the turbo stalling it and then when you put your foot on the go pedal you have to wait for it to spool again. It's worth realising there are two types of dump valve - vent to atmosphere and recirculating. VTA valves basically just open and do as their name says. That's where you get the tsshhh noise. Recirc valves open and the air is directed down another pipe into the air intake before the turbo but after the airflow meter. I've driven with a VTA, a recirc, and no valve at all. VTA's give a chavtastic sound but a awful for part-throttle. It's like having kangaroo petrol. Recircs are in theory the fastest, though I'm currently running my Nissan 200sx without any valve as it's still on a t28 turbo not some huge thing that takes an age to spool.

As for legalities, dump valves in themselves are not illegal. Nearly all turbo petrol cars will have a recirc valve fitted by the manufacturer to aid with driveability and longevity of components (plus, not having one gives a lovely noisy "pidgeon" noise as the air rushes back through the spinning turbo, and generally people get worried if their car makes a noise other people's cars don't..). The issue may arise with exceptionally loud VTA valves under noise pollution regs.

And finally... diesels don't have dump valves, they don't need them as they don't operate a butterfly throttle like a petrol engine.

HTH! I've rambled on a bit.. :D

Joe

dreadnought110:
quote from http://www.dieselbob.co.uk/tuningmethods_plus.shtml
DUMP VALVES


Although not a true tuning option these devices are now available for all engines fitted with a turbo charge including diesels. These devices release excess turbo boost pressure when it's not required i.e. When changing gear, which is often claimed to reduce turbo lag.



Pro’s
Everyone will know your coming.

Something to polish at the weekend


Con's
Makes the vehicle sounds like it has asthma or some serious bronchial problem.


WHO SHOULD BUY A DUMP VALVE?
The perfect companion to a performance filter (something else to polish)
Anyone wanting there vehicle to sound like it has asthma.



DOES DIESEL BOB TUNING OFFER DUMP VALVES?
NO! 8)  8)  8)

Steven:
God, I know all about them now, thanks guys  :lol:

dazliss:
Tut, next we'll be fitting sparkplugs in the tail-pipe to ignite the unburnt fuel to get that true rally car look  :twisted: :lol:  :lol:

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