dump valve

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grayburnett

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im looking for a bit of advice on dump valves,i see loads of people on here like the forge 007p,why is it that you need to use a recirculating valve rather than an atmospheric valve? i used to have a golf turbo and had a piston dump valve fitted with the hole in the air intake pipe blocked off with an aluminium bung,it seemed to run fine.would this work on my a3 1.8t? or is it much better with a recirculating valve?
 
Atmospherics will give fault codes eventually iirc
 
atmospheric seem to work ok on agu engines, any other engines run like crap! so if you have an agu, you might get away with it. my mate has a baileys on his agu and doesnt have any problems at all
 
The engine is designed to run with a recirculating valve, the turbo will be expecting that air back and when it doesn't it'll work harder to replace it and put itself in limp mode/throw up a management light and fault code. Don't fit an atmospheric, just go with a 007P.
 
ok so how do i know if its an agu engine? ive seen golfs and audis on youtube running hks sqv blow off valves too,theres a fitting video showing how to fit atmospheric valves and they blank off the air intake pipe
 
look on your engine (under the engine cover) near the front sorta near the oil filler cap there will be a code pressed into a metal bit!
 
DSCF2455-1.jpg
 
grayburnett said:
ok so how do i know if its an agu engine? ive seen golfs and audis on youtube running hks sqv blow off valves too,theres a fitting video showing how to fit atmospheric valves and they blank off the air intake pipe
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Just don't do it, do a search and you will see everybody who has any decent power runs one. It isn't the 90's, atmospheric dump valves aren't cool and it will make your car slower because it will increase spool times.

If you are running a decent boost pressure then a recirc' gives more than enough noise if thats what you want.
 
Haha, was that an ironic "lmao" Voorhees? :laugh:

s3dave said:
mmmm, people venting there catch cans to atmosphere should be bringing up the same probs as a atmospheric valve im confused....com
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How do you mean?
 
Westle said:
The PCV system isn't directly connected to the boost system so it's fine. It on vented into the TIP originally to meet with emission laws.
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Lol but it will still go into the intake, and on full chat your engine will be blowing like a good un,...so you cant have one rule for one then not for another.....can anybody see what im saying...dont get me wrong im venting mine tomoz, just cant understand how the DV to atmosphere is a big no no ,....but you can vent the breather with no adverse affects (appart from the odd whiff....lol)
The ecu must dial the breather fumes in or the car would run lean...
 
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s3dave said:
Lol but it will still go into the intake, and on full chat your engine will be blowing like a good un,...so you cant have one rule for one then not for another.....can anybody see what im saying...dont get me wrong im venting mine tomoz, just cant understand how the DV to atmosphere is a big no no ,....but you can vent the breather with no adverse affects (appart from the odd whiff....lol)
The ecu must dial the breather fumes in or the car would run lean...
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I don't think your PCV system "adds" anything noticeable other than the odd drip of sludge. And what it does add is so minimal the engine wouldn't need to adjust for it even if it did meter it.

If you do a PCV delete it doesn't throw an engine management light.

The volume of air being dumped back in by the DV is a big enough volume to be expected by the engine, and it allows for that expected air to spool up the turbo quicker as well as add to the air already in the system and meters itself accordingly. If you take that air away it'll still be expecting it, but when it doesn't get it the turbo will have to work so hard to supply the requested air flow that it will go into limp mode. You might not experience it without a stage 1 remap because it will happily boost up to 20/22psi, but if you had a decent map and no recirc valve it would push the turbo too far in some instances and put it into limp mode. This is exactly what happened when we had our A3 mapped, but the problem was due to a boost leak as apposed to the DV.

Its the difference in requested and delivered pressure which puts a fault code and EML on most times, which could be caused by the intake not getting the air back that it would with a recirc DV.

Please correct me if I'm wrong somebody, I'm just talking from my personal understanding of the way it works.
 
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Hold your pcv/catch can return to the tip and get a mate to rev the engine......theres a fair bit of pressure
I am not on about fault codes yet.....lol.....Breather going in un-metered .....yes.......what is compensating for that......ECU....correct?
Breather blocked off ....who tells the ecu ......NOBODY......ecu is still compensating for the breather system......... ok on a custom map not ok for a generic.....please dont say im wrong.......lol
 
s3dave said:
Hold your pcv/catch can return to the tip and get a mate to rev the engine......theres a fair bit of pressure
I am not on about fault codes yet.....lol.....Breather going in un-metered .....yes.......what is compensating for that......ECU....correct?
Breather blocked off ....who tells the ecu ......NOBODY......ecu is still compensating for the breather system......... ok on a custom map not ok for a generic.....please dont say im wrong.......lol
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I do think you are wrong.

The pcv system is completly unaccounted for because it is past the MAF, your 295bhp S3 is probably getting about 236gp/s of air, do you really think its going to miss less than half a gram from the pcv? And you are comparing it to the 30/40 grams that gets dumped by the DV?

Also, because it works on pressure even if the pcv hose was blocked it would just create a stronger vaccum further down the line. Blocking off the pcv hoses would only stop it from sucking crap air from the pcv and instead make it suck fresh air from before the TIP. Because the vaccum has been made it will be filled from somewhere, less holes and take offs in the TIP means more fresh air coming through the maf from the filter.
 
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Venting the dv might work if you've done the n249 bypass, before i do the bypass I vented it and blocked the tip and it went MENTAL at idle.
It is expecting quite a lot of preasurised air though. Id go try it. again but its ******* down.
I can't understand why people are so obsessed with atmospheric penis compensators, you can still hear them, if they wanted to sound like a fast n furious car shouldve bought one. Tells you alot about the person when they want a noise for street cred over the actual function of it
 
put it into the search bar mate. basically though, its an electronic valve that controls the dump valve when the esp cuts in. sits on top of the rocker cover, its part of a huge vaccum system, cant miss it. people, including myself get rid to tidy everything up and also to aid dump valve response.
 
I went for a bailey dv30 as i read about the the problems you get when using the atmospheric valves.



What i don't understand is how this happens as the recirculating dump valve seems to dump through the air filter anyway.


Or am i missing something....lol
 
A3 T said:
I went for a bailey dv30 as i read about the the problems you get when using the atmospheric valves.



What i don't understand is how this happens as the recirculating dump valve seems to dump through the air filter anyway.


Or am i missing something....lol
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The air isnt escaping through the air filter, you can just hear it when it dumps back into the system.
 
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