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try the good old search button, found this from Vagrant N02.
Does exactly wot it says on the tin . It dumps all that lovely built up turbo pressure when the throttle is shut . On a petrol engine it is debated that it stops the turbo from stalling due to sudden back pressure . On a diesel it is not such a prob , most recon you want the turbo pressure not dump it as the engine then has to build it back up again so you could in fact make your Surf slower .
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Only if you want to sound like the dickheads down the McD's most evenings!
I don't know if the Surf turbo makes enough pressure to warrent it, but in theory they will pressure down the intake with the throttle closed quickly, which puts less stress on the turbo and intake pipes. And reduces turbo lag as the turbo isn't stalled by the closed throttle pressure, so when you put your foot down again, the turbo spools up to boost pressure quicker as it's still spinning quite fast.
But like I said, a diesel isn't a racing engine, I wouldn't expect it to show much difference in performance. But if someone trys it and it works, all the good!!
4x4toys.co.uk - Keeping you on and off the road...
there are 2 kinds of dump valves. Atmospheric and recirculating.
Only atmospheric valves make the Mcd's Whoooosh as they dump the charge to the atmos insted of recirculating into the induction system.
Dunno much about diesel turbos, as they are far less exciting than petrol. (I am a saab freak as well and used to have a forge dump valve on my 93 turbo)
On a surf I would expect you would gain more power by platting fog and stuffing this in the exhaust to increase back pressure than you would by fitting any sort of dump valve.
The BOV ( blow off valve) does not have to do the Pshhhh thing, that is caused by the little prats putting a tuned trumpet on the valve outlet.
I had a long hard look at this myself and then at the suggestion of one of the Kiwis on the Aussie forum I disconected my throttle butterfly. The 'fly is only there to trigger the EGR anyway and seeing as that is gone I no longer needed the butterfly. It (he bf) does also make idle and shut down a little smoother but that is a small price to pay for the effect of not having it.
I now have significantly less turbo lag and you can see , on the gauge, and feel the boost come on much quicker.
BTW I am running 11psi at full boot.
A BOV on a manual is ok but a waste of time and money on an auto.
Nev
This is what i was about to say An AUTO does never shut the engine off as you do not change gear so there is no point trying to fit a dump valve as you dont close the throttle to change gear see....................
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