Hello
I was wondering if Dump valves works on turbo diesels(the ordinary ones) I know it is a bit silly question and dump valve sound wouldn't match to a car like xantia as its not a boy racers car but I find the sound quite amazing. Has anybody experienced or knows if they would work on TD xantia?
Thanx alot
Dump valves on TurboDiesels
Moderator: RichardW
the air intake isnt throttled anywhere like a petrol turbo so no they dont work,
However, some people that were obviously rather desparate to have the petrol dump valve noise on their turbodiesel have come up with a kit to make it work, I believe it simply stores some of the boost pressure in a bottle and vents it when signalled to do so by solenoid controlled by a switch you connect to the accelerator or brake (cant remember which)
However, some people that were obviously rather desparate to have the petrol dump valve noise on their turbodiesel have come up with a kit to make it work, I believe it simply stores some of the boost pressure in a bottle and vents it when signalled to do so by solenoid controlled by a switch you connect to the accelerator or brake (cant remember which)
It depends on what you mean by work?
Dump valves release pressure, simple as. On a petrol they release back pressure so that it doesn't interfere with the spinning of the turbo (back pressure would hit the turbo the 'wrong way' and cause the turbo to 'stall'). The diesel however doesnt have any back pressure to be released!
When changing gear is when the petrol is mostly affected by the back pressure (ie lifting off the accelerator) and seriously slowing the turbo, by having a pressure release the turbo isn't slowed and is still 'spun up' when you have made the gear change. In releasing the pressure there is a 'whoosh' noise, and its the only real obvious sound. On a proper dump valve the released air is recirculated back into the turbo the right way round to keep the speed up, but there is very little sound. These are unsurprisingly known as recirculating dump valve and a lot of Audi's and VW's have them fitted and are of PLASTIC construction, and dont seem to last long!
Now, diesels! Well they dont have back pressure to be lost. In theory you can vent some forward resistance and stop the turbo slowing, but the theory is 'rollocks' and they make litle if not no difference to the turbo speed. But they will release pressure and make a 'whoosh'
So yes they do wok in as much as they make a boy racer come fast and furious 'whoosh' noise but thats about it, unless you have a recirculating DV which makes no noise and is a little pointless! But the cost is stupid! For a good diesel DV which goes 'whoosh' not a fart noise, will cost around £180 (search on Google for Derv Doctor or Allards Motor Sport, there the only people who really know there stuff!). A recirc valve (plastic one from a VW/Audi) will set you back about £15 but make little difference and dont go whoosh!
Basically for a diesel if you want to pimp your ride, then they work! If you want the car to go faster, then they dont! Hell if anything it will slow the turbo by leaking boost! The sort of system that Mosser is talking about is the way you get you N/A Fiat Uno to have a turbo noise! or you can stick a 'fart' mechanism in the tail pipe to get a similar effect with the added bonus of turbo 'spin up' noise!
Dump valves release pressure, simple as. On a petrol they release back pressure so that it doesn't interfere with the spinning of the turbo (back pressure would hit the turbo the 'wrong way' and cause the turbo to 'stall'). The diesel however doesnt have any back pressure to be released!
When changing gear is when the petrol is mostly affected by the back pressure (ie lifting off the accelerator) and seriously slowing the turbo, by having a pressure release the turbo isn't slowed and is still 'spun up' when you have made the gear change. In releasing the pressure there is a 'whoosh' noise, and its the only real obvious sound. On a proper dump valve the released air is recirculated back into the turbo the right way round to keep the speed up, but there is very little sound. These are unsurprisingly known as recirculating dump valve and a lot of Audi's and VW's have them fitted and are of PLASTIC construction, and dont seem to last long!
Now, diesels! Well they dont have back pressure to be lost. In theory you can vent some forward resistance and stop the turbo slowing, but the theory is 'rollocks' and they make litle if not no difference to the turbo speed. But they will release pressure and make a 'whoosh'
So yes they do wok in as much as they make a boy racer come fast and furious 'whoosh' noise but thats about it, unless you have a recirculating DV which makes no noise and is a little pointless! But the cost is stupid! For a good diesel DV which goes 'whoosh' not a fart noise, will cost around £180 (search on Google for Derv Doctor or Allards Motor Sport, there the only people who really know there stuff!). A recirc valve (plastic one from a VW/Audi) will set you back about £15 but make little difference and dont go whoosh!
Basically for a diesel if you want to pimp your ride, then they work! If you want the car to go faster, then they dont! Hell if anything it will slow the turbo by leaking boost! The sort of system that Mosser is talking about is the way you get you N/A Fiat Uno to have a turbo noise! or you can stick a 'fart' mechanism in the tail pipe to get a similar effect with the added bonus of turbo 'spin up' noise!
I recently fitted one to a mates Xsara HDi (i fully explained to him that it would do nothing apart from make the noise which is all he wanted it for).on this setup a small microswitch was fitted onto the throttle potentiometer that closed the switch when you let off the throttle & operated an electrovalve that was fitted to the vaccum pump to open the valve.biggest waste of £200 ever,it sounded nowhere near as good as a petrol one & made a mess under the bonnet with oil vapour everywhere.
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julian2002
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just an fyi here but the latest vw tdi pd engines use a garret variable geometry turbo and dump valve. they sound like plumbing though not the crisp tssshhhhhh you get from a petrol turbo. if you get the chance to drive one accelerate hard in 2nd up to about 1700 - 1900 rpm and then lift off & dip the clutch spewlurgle.