(G) waiste gate / dump valve

on my car i have a waiste gate which i prefer the sound of.
what is the difference between the 2 is it that the w/g throws air out and sucks it in at the same time, where the d/v just gets rid of it all.

Wastegate vents exhaust manifold pressure to regulate boost pressure.

Dump valve vents excess boost pressure in the boost pipes created when the throttle is snapped shut.

and in english
so is there any difference in performance

The wastegate is what makes the turbo a usable component

A dump valve aids the turbo so it will keep spinning between gear changes (Stop compressor stall or Air Flow Meter flutter)

Both the above are bad for the two mentioned components but compressor stall and waste gate chatter are the ********! lol

type: AUDI in www.streetfire.net search and youll hear why!

To expand on what Steve said...

The standard Uno Turbo has both a wastegate and a dump valve. You don't normally hear either of these because they are 'internal' and 'recirculating' respectively.

The wastegate opens to give the exhaust gas an easy path to the muffler, not going through the turbocharger. This prevents the turbocharger from working too hard, so the wastegate limits the maximum boost pressure (normal limit: 0.6bar). This is to ensure reliability of the engine by restricting the maximum temperatures and loads.

If you have a bleed valve fitted, it changes the point at which the waste gate opens. It's called a bleed valve because it bleeds off some of the pressure in the pipe to the wastegate opener (correctly called 'actuator'), so that the wastegate doesn't open until the boost pressure gets higher than normal.

I'm guessing that you have an 'external' wastegate, which I'm also guessing will release the exhaust gas directly to the surroundings? Apart from the noise I can't see any other difference in performance apart from probably having the actuator calibrated to a higher pressure than standard.

If there is boost pressure going into the engine, and then the accelerator is released sharply, the throttle plate closes and the boost pressure momentarily has nowhere to go - excess boost could surge back into the turbocharger's outlet causing 'compressor surge'. The dump valve opens in these conditions to let the excess boost go around into the inlet of the turbocharger (recirculating type), or an aftermarket external dump valve lets the excess boost out into the surroundings as a Tsshhhhhhh.

(This loss of boost then means that when the throttle re-opens, the turbocharger cannot build up boost pressure again until more air has been drawn in, which in so doing comes through the fuel injection system's airflow meter... causing the fuel injection to inject more fuel to match the extra air... and for this reason I personally don't see the point of an external dump valve, even though they are cool to have.)

Incidentally Biz is absolutely right in pointing out the very real purpose of both these components, which is why the Uno Turbo has both (wastegate+dump valve) as standard.

Hope this helps, please say if still confused
I'm thinking you must have a larger turbo as well to get 170bhp, so maybe you'd like to share what your setup includes?

-Alex

all i know is that it has a hybrid , fuel modification , upgrade actuactor and the other little bits eg k+n. i have dyno print out of 170bhp / 180 torque .
i can hear the w/g but not the d/v . wehre the d/v goes it is blocked of

How do you know you can here the WG? Unless it has no exhaust (or a "screamer" pipe) you cant.

What exactly do you want to know?

Standard Uno Turbos have a BOSCH bypass valve (No noise when coming off the throttle)

Uno170 mate is the noise you hear of a flutter? (like a pigeon in a way)

on my old MK2 i used a sized ****ty dump-valve and that caused the un-used air when i came off the throttle to go back past the turbine blades in the turbo and "fight" the incoming air in the air flow meter (AFM)..............and results in the flutter sound............NOT good for the air flow meter

Have you got another dump valve to check to see if your current one is faulty?

and how long has it been doing this?

i have waiste gate make spig noise ( not tssssss) i thought the d/v goes on that big turbo hose where mine is blanked i will post photos 2morrow.
wat is better w/g or d/v

"i have waiste gate make spig noise" What the F%^& does that mean? Its a wastegate anwyay. You have both a wastegate and dump valve from the factory.

i meant pigeon noise .
where is the d/v located

'd/v' is a T-fitting on the side of the large air pipe going into the turbocharger. Look down behind the airflow meter. Or look on the vertical metal pipe at the front of the engine - the uppermost pipe goes off to the right, around the corner, and into the 'd/v'.

-Alex

im sure i dont have a d/v i have the t piece but it is blocked of think i just got a waiste gate
so can i run both d/v + w/g ?
then the noise would go tssss pigeon ?
is the any difference in performance wise between the 2 or just the noise ?

this is my engine

<<<then the noise would go tssss pigeon >>

No, The whole point of the DV is to remove this noise. If you want the noise, leave the DV off the car.

The noise is compressor surge which is not very good for the turbo.

The wastegate is not at all part of this.