Dump valve on my 2.0 turbo

**jonnya** · 29th July 2009, 14:39

would i get any benefits from putting a dump valve on my 2.0 turbo i have heard it can prolong the life of the turbo and heard other stories.

**67688c** · 29th July 2009, 15:05

Excuse my ignorance, but what exactly is a dump valve?

Is this the gadget that youngsters often fit to their go-faster noise making cars, which makes a sort of loud whoosh noise everytime they change gear when accellerating... LOL ?

Just wondered!

**PORKBALLS29** · 29th July 2009, 15:08

You allready have a recirculating dump valve fitted to the 2.0t so if you have the windows down you can hear a very faint woosh and spit when the turbo dumps the pressure. I have seen quite a few threads on here about problems with fitting after market dump valves so I would still well clear. It doesn't appear that you'll get any fruther benefits. HTH

**vectrac20tsri** · 29th July 2009, 15:37

i had a dump valve on my vectra and it sounded good forge motorsport do the kit and its not to loud on the vectra,as long as you have a twin piston dump valve you will be fine,i changed the forge one for a bailys twin piston off an rs turbo never had a problem,

**sdemps** · 29th July 2009, 15:51

Technically external dump valves are bad for turbo's, they can make the turbo stall as it dumps the boost pressure out rather than back into the engine therefor making the turbo work harder. If you like the noise then go for it, it's a personal thing at the end of the day some folks like them others don't (usually the folks that don't have turbocharged cars).

**Steven** · 29th July 2009, 15:53

No benefit's at all mate....

**John C S** · 29th July 2009, 15:55

A bit chavvy is a dump valve.

More your Fiesta RS turbo than a Vectra!

Let us Hypnotise you............

DON'T DO IT - FITTING A DUMP VALVE WILL MAKE YOU A CHAV.

Your back in the room!

**soulman** · 29th July 2009, 15:58

Oh my gawd and laffing soooooooooooo much I'M

nice comments JC

**AntB** · 29th July 2009, 17:13

Originally Posted by John C S

A bit chavvy is a dump valve.

More your Fiesta RS turbo than a Vectra!

Let us Hypnotise you............

DON'T DO IT - FITTING A DUMP VALVE WILL MAKE YOU A CHAV.

Your back in the room!

Sounds like a job for Hypno-toad!

**csd_19** · 29th July 2009, 18:05

Originally Posted by sdemps

Technically external dump valves are bad for turbo's, they can make the turbo stall

Not quite right...

Turbo stall is what happens if you remove the DV altogether or remove the vac hose running to it, and the built up boost pressure in the pipework has nowhere to go when you close the throttle. The air reverses direction and tries to flow against the turbo, hence "stalling" the compressor blades. The stalling gives a noise similar to an external wastegate, that "cha-cha-cha" that WRC cars make; excpet this puts a huge strain on the turbo shaft and will shorten the turbo life.

BOVs (blow-off-valves, let's give them their proper name) can be fitted, but as vectrac20tsri has already said make sure its a twin piston one.

In a turbo system which uses a MAF for fuelling, the standard setup uses a recirculating DV to dump boost back into the intake side of the turbo when you lift off the throttle. The ECU will be setup to take this recirculating air into account when the throttle closes.

With the normal recirculating DV (dump valve) it will be held open at idle due to inlet vacuum. Again the ECU knows that some air will be doing a loop through the recirc DV in the intake system, and the fuelling will be adjusted to allow for this and give a smooth idle.
With a single piston BOV, this ends up fully open at idle, and the air that would normally be recirculated is lost - this can causes idling issues and stalling. The twin piston design counteracts this and allows a smooth idle as it closes fully.

One way to get around the stalling issue is to unplug the MAF - now I don't know if the Veccys still run with it unplugged? I know it works on VAG 1.8T engines, only downside is it makes the engine runs slightly richer than normal as it then uses the MAP sensor and the AIT sensor to sort out the fuelling instead of the more accurate MAF.