Hi all,

I went to the ISTS show yesterday and was amazed to see countless dervs...with dump valves! lol, back when I had my Golf and Bora im sure you had to have some kind of compressor to give the air for the whooosh, or has this all now changed?!?

Cheers

Dave

how big were these dervs with dump valves?

real big diesels with huge turbos running 50 psi + will soon kill off a turbo if the pressure is not vented somewhere so there are used, but not on our little 4 pot's with vnt15/17 etc...

you can buy kits on ebay to fit any diesel, they are opened by a microswitch under the accellerator pedal so when you let off from "foot to the floor" it will open and vent boost pressure to atmosphere.  

One was a Fabia VRS and another was a Pug 306, well never knew that before, cheers!

 My golf mk4 gt tdi 130 has a dump valve but is standard otherwise i'd remove it as its rather anoying lol, once driving get the revs up to around 2,000 with foot half way down on accelerator then lift off, it dumps the excess turbo pressure

when flooring it and releasing my foot off the acc, the CAI i have makes a "dump valve" like noise

i guess this is due to the "bigger" turbo i have??

 i had a dump valve fitted to my old 306 td about 6 years ago.was about £300 didnt improve the performance but did turn heads

14N GTTDI:

 My golf mk4 gt tdi 130 has a dump valve but is standard otherwise i'd remove it as its rather anoying lol, once driving get the revs up to around 2,000 with foot half way down on accelerator then lift off, it dumps the excess turbo pressure

golf diesels dont come with dump valves standard. maybe someone has had one fitted or it is just the pressure in the pipes and turbo making a dump valve like sound. the 150pds with a derv doctor dump valves sound nice.

i had one on my mk3 golf tdi.

as with the 306 no performance. but it was amusing seeing peoples faces.

dervdoctor sells them

Isn't it just an external wastegate... I hear some noise on my anni... not a dump as such.

a wastegate vents exhaust gasses away from the turbo once desired boost has been acheived.

on TDI's some people do hear dump valve like noises, i personally get this and i think it is a boost leak somewhere and it's doing my head in trying to find it. i used to hear a whooshing thru the exhaust when i let off, now i get a pssssss noise like it's leaking somehwere and also a hiss as boost builds.

a carbonio or similar designed filter will make an noise "like darth vader" is the only way i can describe it lol. similar to the noise of a recirc valve in operation on a pterol turbo 4 pot

 is it worth getting a dump valve for a tdi then ??

Ka1neO_TDI:

 is it worth getting a dump valve for a tdi then ??

nope

av got a forge dump valve fitted to my gt tdi golf

(300 pound to make it go psssssshhhhhhhhh...)

i got the fitting kit for mine +  linked to the ecu and gets + linked to the brake servo for pressure.

T8UPS:

14N GTTDI:

 My golf mk4 gt tdi 130 has a dump valve but is standard otherwise i'd remove it as its rather anoying lol, once driving get the revs up to around 2,000 with foot half way down on accelerator then lift off, it dumps the excess turbo pressure

 

 

golf diesels dont come with dump valves standard. maybe someone has had one fitted or it is just the pressure in the pipes and turbo making a dump valve like sound. the 150pds with a derv doctor dump valves sound nice.

mine was brought from a trade seller and it was a company car so it wasn't played around with, my friend had a mk 5 golf diesel and that was brand new ( was a courtesy car) that had one. i herd a renault laguna 57 plate have one driven by a grandad! one other thing if i have all the windows up i can here the internal wastegate inside the turbo it sounds like a pigeon type coo its only very quiet tho, i have herd it on an ibiza not sure what bhp engine but it did for some reason have a lorry exhaust sticking out the back, that made the wastegate sound louder! lol

 I "HAD" one on my old Pd130 Ibiza, Was good at first, then got on my nerves and i took it off as it wastes precious boost.

 How did you remove it as i was under the impression that turnos need a pressure release valve of somekind to function properly as mine goes off or 'dumps' even if i keep my foot on the gas pedal, where was yours located?

14N GTTDI:

 How did you remove it as i was under the impression that turnos need a pressure release valve of somekind to function properly as mine goes off or 'dumps' even if i keep my foot on the gas pedal, where was yours located?

The turbo will still have a wastegate, the wastegate relieves excess pressure.

The dump valve is designed to release the pressure from the pipes between the butterfly valve and the turbo when lifting off the throttle. This is to stop the turbo stalling.

Diesels don't have butteryfly valves so don't need a dump valve.

The after market kits are purely for the noise. They use a solonoid valve to act as a vacuum "switch", the vacuum is taken from the vacuum brake pipe. The solonoid is triggered by the  switch on the accelerator pedal. (as said above). Then vacuum sucks (no jokes) the dump valve open.

14N GTTDI:

 How did you remove it as i was under the impression that turnos need a pressure release valve of somekind to function properly as mine goes off or 'dumps' even if i keep my foot on the gas pedal, where was yours located?

how do you remove something thats not there? hmm that is a tricky one!

the mk4 and Mk5 TDI's (and most other production diesels probably) DO NOT have dump valves fitted as standard. it may sound like it but they DO NOT have them.

 a wastegate is nothing to do with a dump valve, it is located on the exhaust side and simply diverts exhaust gasses around the turbo when it reaches desired boost. what we have on most of our TDI's is a slightly different system but similar nonetheless; variable nozzle turbo's,  which control the flow speed of the gasses past the turbine to alter the speed of the turbine.

a dump valve relieves the excess pressure on the charge air side of the system, so when you change gear the excess pressure doesn't stop the turbo spinning. on a diesel there is no throttle body and thus no sudden pressure spike so no need for a dump valve,.

unless it's a huge diesel engine running 50psi of boost, in which case a dump valve would help but a recirc valve would be better