UK-POLOS.NET - THE VW Polo Forum

Hi,

When I look at the back of the engine from the top next to the engine cover I can see a black plastic device. It looks similarly like a dump valve, but directly connects back to the air intake between the air flow meter and the turbo.

Doesn't this reduce performance!?

I think all turbos need dump valves to release the excess pressure. Just the standard ones are silent compared to aftermarket ones you can buy. Just what ive heard tho. Not sure about it reducing performance.

i dont get what you mean by 'reduce performance'. what i think you want to know is whether they can be improved on with aftermarket equipment???

i think by the sounds of thinks it has a recirculating dump valve fitted??

Mines a recirc dump value - but i'm not any use as mines denzil!

All VAG's from what I've learnt (Turbo wise I'm talking) will have recirculating dump valves. Atmospheric one's can confuse the engine management from what I've been told.

In petrol engines (VAG) it is possible to fir an atmospheric dump valve (for those that don't know this is what makes the loud paacchhssshhh noise in some turbo'd cars) however a new/seperate engine management is required.

Diesel's it's possible but again needs to be wired up as it has something that communicates with the enginemanagement to make it effective. (see forge's website for that one as that's what i'm thinking of)

all turbochargers have a dump valve to release pressure. that pipe could be an oil feed return or a return breather pipe.

Thanks,

I will use this info to find out more about the engine management and the effects/consequences of making the oem dump valve dumping pressure into the atmosphere.

My Dad's Mk5 Golf GTI makes a very slight dump valve noise when changing gear

the audi / vw turbo lumps have recirculating dump valves, not dump-to-air valves. if you want a part recirc/part dump-to-air valve for the sound, you need to buy something like a forge dv007 i think. VAG lumps do NOT dump-to-air by default.

I have looked into this aswell, a wouldnt do it if i were you. Putting dumping to air will confuse your engine managment as it will wonder where all the pressured air has gone that was meant to be recirc'd Plus taking away the pressurised air will reduce the power of the turbo, plus it gets annoying hearing psssssssssss pssssssssssss psssssssssssssssss

You do not want to be fitting an atmospheric dump valve to a VAG engine.

The one currently fitted is a reciculating one. You can upgrade the recirculating one, you wont see any power increase by upgrading it, but VAG platic recirc valves are a known weak point and can eventually wear and leak and cause ecu faults.

I've fitted a Forge 007p recirc valve to my 9N3 GTI

Although just to confuse things, Forge have recently launched a valve which apparently dumps to atmosphere and is still compatible with the VAG recirc system, how they've done it i do not know lol

maybe it dumps a little to air and re-circs the rest??? wouldnt mind gettin one!