General waiste gate / dump valve

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General waiste gate / dump valve

I'll try and clarify things for you.

To keep things simple consider two groups of moving gas, exhaust and boost.

The boost is clean air sucked into air filter, through the turbo and pushed around the boost pipes through the intercooler and eventually into the inlet manifold that sits on the engine (big shiny allow thing, says 'turbo ie')

Exhaust gases are whats left after combustion and they exit the engine via the exhaust valves they then pass through the exhaust manifold and into the other side of the turbo before finally leaving through the exhaust system.

The turbo has two sides, hot and cold nicked name that way for obvious reasons! The cold side flows the boost and the hot deals with exhaust. The turbos two half's can be considered seperate for simplicity and no gas can flow between the two in any case.

That should give you a basic understanding so i'll explain about dump valves and wastegates now.

The wastegate is built into the hot side (exhaust side) of your turbo and does not come in contact with any cold air the flow into the engine. The vast majority of turbos have them built in its not a performance mod to add one and you cant remove it (pease no one bring up EWG's!!). However and this is the bit that will confuse you if any: The wastegates job is to determine how much boost the turbo is to run. It does this by allowing exhaust gases to pass by the turbo's turbine blades and straight into the exhaust system thus not contributing at all. So in english its a little flap that opens, how its does so can be left for another time i think!

All (most at least) petrol turbo'd cars come with a silent dump valve (recirulating). Its job is to stop boost (cold new air) damaging the turbo when its entry to the engine is halted due to a lift off of the throttle.

So both the dv and wg are needed and carry out completely seperate jobs.

If you didnt have a dumpvalve you might hear a fluttering noise, this is the compressor (cold side wheel) stalling at the boost returns and hits the veins going the wrong way. Its the reason you have a dv and prevents large forces loading the bearings and wearing it out your turbo prematurely.

Any questions?

Tom
 
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Does you car have the recirculating (almost silent) one it cam with still?

Its black, plastic and will be poking out of the inlet boost pipe that carries air form the air flow meter to the turbo inlet. if you car has an after market air filter then follow this pipe down towards the turbo and on the underside of this pipe there will be a pipe coming off it and just there will be the dv.

You can buy either an after market recirculating one (better performance but no noise) or an atmospheric one that makes the twiiiisssssssss noise.

I recommend the bailey dv's (dv26) as they seem to last for ever and never stick.

Tom
 
im not sure i will have a look
the person who had it b4 me had one on there but i suppose he took it of and connected it backl up to original. :confused:
ill have a look and let u know
 
nope dont really know wat im looking for
anything in these
any1 else got a picture of it
 

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Looking at the pic of your engine bay it seems to me that your car has at some time in the past been fitted with an after market style dump valve, you have the T piece coming off the top boost hose which is where it would normally be but looks like its been blocked off and this is creating the wastegate "chatter" sound as its called. As steve said its not good for the turbo but i gotta say it does sound really cool. :cool: My mate took his DV off his fiesta Turbo and it sounds sssso sick!!!

:cool: F R O $ T Y
 
does the original 1 stay on the car all the time so counld he off taken the pipe of the new d/v then blocked pipe off .and put the pipe back on the old 1 or not.

would a blue anodised d/v look good or shall i go silver
 
Yes and no. You cant upgrade the one built into the turbo or at least its not common and isnt off the shelf.

You can ditch it by either welding it up or other means and buying an external waste gate which requires you moddifying your down pipe (exhuast) and exhaust manifold. Not cheap and not worth it unless you're after near perfect boost control and big bhp!

Tom
 
the mk1 kid said:
Yes and no. You cant upgrade the one built into the turbo or at least its not common and isnt off the shelf.

You can ditch it by either welding it up or other means and buying an external waste gate which requires you moddifying your down pipe (exhuast) and exhaust manifold. Not cheap and not worth it unless you're after near perfect boost control and big bhp!

Tom

better got me welder out then

Dunc
 
When i get around to it Dunc i'm not going to weld mine but keep it shut as follows:

As you blank of the wastegate part of the elbow you put a bolt through a tapped hole and thread that up against the wg flap. Do this up tight (and test it with a compressor) before welding it in place. This way your turbo cant possibly get damaged in the process and its usesable again in oe form.

Tom
 
Seems as people are talking about the w/g & d/v sounds. How about people upload some sound files of theirs.
That way people can see what set ups get what results (as sound is cool (y) ).

I also just love the sound, so jelous of all you turbo owners out there :slayer:
 
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alexGS said:
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

couldent have said it beter any how extra fuel cases bore washing and over problems and who wants that just for a tishhh
 
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