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Dump valves query

Discussion in 'A3/S3 Forum (8L Chassis)' started by Mi11ar, May 26, 2013.

  1. Mi11ar
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    Mi11ar Member

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    I was thinking of getting a more atmospheric dump valve but was warned that the 1.8T Audi engine responds badly to them, and can dramatically reduce performance.

    is this simply rumor?

    At the moment my A3T is standard but as my first mods I'm getting a K&N panel filter and was considering a louder dump valve hence the thread.

    Also can people give recommendations towards which valve to purchase etc?

    Thanks :)
    #1
  2. Blackcupraa
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    Blackcupraa Member

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    Replace the stock valve or get a 007p / baileys. Atmospherics are bad!
    #2
  3. stuart_tate41
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    stuart_tate41 Member

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    You're best with a recirculating valve like a forge 007p
    #3
  4. Mi11ar
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    Mi11ar Member

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    So they are bad, thanks :)

    I'll check them out cheers
    #4
  5. Mi11ar
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    Mi11ar Member

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  6. s33nyboy12
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    s33nyboy12 Well-Known Member

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    Just lose the thought train of an atmospheric dump valve, its a no go on a3 1.8t. Buy jap turbo if you want a massive dump valve.

    However to get a "nicer" sound, consider a b5 tip with an s2000 filter and cold air feed coupled with a forge 007 diverter valve. ;-)


    Sean
    #6
  7. s33nyboy12
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    s33nyboy12 Well-Known Member

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    #7
  8. jack_davey
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    jack_davey Member

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    Why are they 'bad' on a 1.8T?
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  9. Mi11ar
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    Mi11ar Member

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  10. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Been discussed a million times...

    VAG ecu's measure the air using the MAF (mass airflow sensor)... it knows how much air it has and knows how much injector duty to get the right AFR... when you let of the throttle the air in the system 'dumps' to protect the turbo but it recirculated back into the intake... this way the ecu still knows how much air is in the system to fuel accordingly... if you vent this air to atmosphere it can cause the engine to run rich as the charge system has less air in it than the ecu thinks it has... this can cause misfires, stalling and generally make the engine run badly...

    <tuffty/>
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  11. jack_davey
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    jack_davey Member

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    I can understand the theory behind that, but surely inevitably, some of that metered air is lost back out of the air filter when the recirculating valve is opened?

    Also despite the air being metered by the MAF, the reason the air is being recirculated or 'dumped' is as a result of the throttle being closed anyway, so regardless of what duty cycle has been calculated for the injectors at WOT, the fact the throttle is now closed means hardly any of that air passes the throttle?

    Do these cars not also have a MAP sensor that would detect the sudden drop in pressure from an atmospheric dump valve?
    #11
  12. A3-Lee
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    A3-Lee Active Member

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    I had an atmospheric on my 1999 1.8t AGU for 18 months and it was fine but took it off as i got bored of it lol I'm now running a oem 710n DV and s2000 filter and the noise is amazing
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  13. 16Klappe
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    16Klappe Princess Slayer

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    Wow.

    Surely the amount of times Tufty and myself have answered the questions above means there can't be many people left in the UK who don't know the answer.

    If you can't be bothered to use Google, why should we bother to answer for you.

    :(
    #13
  14. Mi11ar
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    Mi11ar Member

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    This Friday I'll get a panel filter and one of the suggested valves, providing I don't have any dramas with them, I'll get an exhaust system possibly with decat.

    And I did use google but there's conflicting opinions just wanted to clear it up with you guys.
    #14
  15. s33nyboy12
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    s33nyboy12 Well-Known Member

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    this is what I thought jaardo! If you type in a3 1.8t dump valve in google it brings up 6 results from as.net alone. Even my mrs knows why you can't have an atmospheric BOV on Audi 1.8t :).
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  16. 16Klappe
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    16Klappe Princess Slayer

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    I am more than aware of this.

    Can we change the forum registration so that instead of having a captcha image it ask "should you fit an atmospheric DV to a 1.8t"
    #16
  17. s33nyboy12
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    s33nyboy12 Well-Known Member

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    Lol agreed!
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  18. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    What do you think a recirculating valve does? yes... there is a map sensor but the pressure will drop whether you use a recirc or an atmos valve... the map sensor doesn't measure air or air flow, it doesn't care where the air has gone... out to atmos or back in the inlet tract its still pressure drop... the maf does and the maf has already metered this... if the air lost from an atmos valve was metered on the way out then the ECU could arguably compensate... but it isn't... you vent the air to atmos then it will run rich... thats how the VAG ecu's work... they calculate fuel etc based on stuff thats measured...

    As for losing a little out the airfilter... maybe it does but the ECU is clever enough to have accounted for this... when you release the throttle do not assume its closed as you do not control it, the ECU does... the throttle pedal just tells the ECU how fast you want to go... the ECU makes that happen...

    <tuffty/>
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  19. Mi11ar
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    Mi11ar Member

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    Well as I said thanks or the replies, and again I did already google it but there was contrasting opinions and I wanted to know from the horses mouth so to speak.

    This is the first VAG I have owned so still learning.
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  20. s33nyboy12
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    s33nyboy12 Well-Known Member

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    jack_davey

    I can understand the theory behind that, but surely inevitably, some of that metered air is lost back out of the air filter when the recirculating valve is opened?


    Also despite the air being metered by the MAF, the reason the air is being recirculated or 'dumped' is as a result of the throttle being closed anyway, so regardless of what duty cycle has been calculated for the injectors at WOT, the fact the throttle is now closed means hardly any of that air passes the throttle?


    Do these cars not also have a MAP sensor that would detect the sudden drop in pressure from an atmospheric dump valve?

    ?
    Wtf, is this guy trying to tell P.T about vag 1.8T engine setup ????

    Ban him :)
    #20
  21. Tim_Attard
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    Tim_Attard Active Member

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    if you want the sound, get a tip + s2000 filter and stick with a standard valve, i was stupid and got a split-r when i first got my car, after fitting the above i swapped back to standard and it makes a better sound than the split-r did anyway dont see why you would go atmos
    #21
  22. jack_davey
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    jack_davey Member

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    Wasn't trying to lecture anyone on here, if you notice every sentence I wrote had a question mark on the end.

    I'm trying to understand the topic better. I'm new to VAG cars, but not at all new to automotive technology or ECUs.

    I don't doubt that a atmospheric dump valve doesn't work well with a MAF equipped car, but I'm not sold on the reasoning that is being suggested here.

    True, the throttle is never really closed as such as most cars incl. the 1.8T (apart from the very old cable throttle versions) employ a drive by wire throttle and it is always slightly open to allow the engine to idle.
    BUT the main reason the system needs to recirculate or dump the pressure is because the throttle plate is mostly closed and thus the air has nowhere to go other than back out of the turbo, and this can cause compressor stall (the fluttering noise) which will damage the turbo.
    #22
  23. 16Klappe
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    16Klappe Princess Slayer

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    When will it end.

    Ppppllllleeeeaaaasssseeeee can we just stop talking about dump valves, I'll do ANYTHING. I've had five years of logging onto ASN and seeing the same question asked in the same way and given the same answers by the same people. I'm not sure my brain can take enough of this, my mental hard drive is about to fail.

    I think if I see another dump valve question my mind may well erase my entire life learnings to create a partition for "Useless **** I don't need to know because Google knows it for me."
    #23
  24. kan-e
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    kan-e New Member

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    i dont no why you are flipping you dont have to read the thread... this lad has just come a cross to the vag seen and was after a bit of help... and were would be best place to get that help???

    Google... not true

    the best place for help is from the ppl that are in the no on this site as he can ask questions on how and why and whats best...

    i have my self just bought a a 1.8 turbo that has a dump valve fitted so i think this is a good thread even tho its been asked loads of times...

    do you not ask questions!

    if you dont ask you will never no!

    on the body building forum every day there most be five ppl joing asking the same question so we point them in the direction of the sticky threads maybe some one should do one on here for the dump valve....
    #24
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  25. 16Klappe
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    16Klappe Princess Slayer

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    Mate.

    This **** has been covered three time THIS WEEK and as I am sure you are aware it is only 10AM Tuessay morning.

    And no I don't ask questions, I research, understand and then make my decision. Once my decision is made I help inform others on my experience.

    I'm all for helping people and sharing knowledge, but this really is a daily thing which is always answered in exactly the same way, and then followed up by somebody who doesn't really know contradicting what has been said, then someone who hasn't got a clue saying it worked fine on theirs.

    Google, search, basic thought process behind how a DV works...All lead to the same answer.

    The purpose of a DV in its most simple form is to release pressure to save compressor stall, releasing to atmosphere is one way. A better way to release the pressure would be to re-use that charge to aid the turbo on re-application of the throttle.

    It really is that basic, and if you don't understand those basic principles of forced induction then you have no place playing with the set up and should be taking it to a specialist to do the work for you.

    I know I sound like a total vagina, but it has to he said.

    P.S, I ran an atmospheric valve for two thousand miles+, noticed no running faults as such (mapped ME3 AGU) however my fueling was miles out on over run and the car was considerably healthier when I went back to my Forge 007p which I had been running forever.

    I have had a Bailey DV30, a Bailey DV26, two Forge 007P's, I have tried a Split R, I have tried three revisions of the 710n.

    And now that I have got the most powerful K03s A3 in this country, guess what DV I run? Uhhuh...Standard 710N bought from TPS.

    Stick with the OE valve, fit a cone filter, up the boost. My car is easily as loud as an atmospheric valve when it drops 22psi if that is what you want, and it drives better for it.
    #25
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  26. kan-e
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    kan-e New Member

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    think you should make a sticky thread...
    #26
  27. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    No one reads them :(

    <tuffty/>
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  28. Vex182
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    Vex182 Guess what I drive...

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    I agree, more regular users read them but new users just dive right in with questions.
    #28
  29. 16Klappe
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    16Klappe Princess Slayer

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    The irony burns me.

    :(
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  30. [Dave B]
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    [Dave B] Rrrrrrrr-tech

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    If you really meant this, then you my friend are a legend.
    #30
  31. s33nyboy12
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    s33nyboy12 Well-Known Member

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    Lol! This is priceless , I kind of want to open a new username and profile and ask this question on as.net again I think jaardo would have a meltdown...... :)

    Sean
    #31
  32. 16Klappe
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    16Klappe Princess Slayer

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    Potentially. It is just a base incompetence which outlines a fundamental flaw in intelligence. Which in turn undermines any potential merit for completing the work to a satisfactory level.

    Can't read a big banner which says FREQUENTLY ASKED QUESTIONS, probably can't wield a spanner.

    :beerchug:
    #32
  33. s33nyboy12
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    s33nyboy12 Well-Known Member

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    The infamous forum quote of " weeding out the thick and educating the misguided" ! Lol
    #33
  34. boost-addict
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    boost-addict Member

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    so what stops you running the maf just before the throttle body? just a qestion !!!
    #34
  35. badger5
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    badger5 www.badger5.co.uk Site Sponsor

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    because the system was not designed to do that...................
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  36. boost-addict
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    boost-addict Member

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    fair comment. is there a reason why it wouldnt work, always been curious to know if it would work and why it wouldnt if its not possible
    #36
  37. superkarl
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    superkarl MAN OF STEEL

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    so you werent joking when you posted that????!
    how about the fact it would be after the turbo, so wouldnt be measuring injested air which its for. So then how would the car know what its taking in?
    It would then be measuring pressurized air being forced in at godknowswhat mph, so the engine would think it was consuming enough air for 1000hp. In fact, the maf would max out constantly, so thats another reason.
    #37
  38. boost-addict
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    boost-addict Member

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    ah ok.no harm in asking! there are other turbo'd cars with the maf after the turbo
    #38
  39. superkarl
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    superkarl MAN OF STEEL

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    i bet you £100 there arent
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  40. kan-e
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    kan-e New Member

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    iv just put in search bit.. dump valve... there are loads of threads on people asking...

    :keule:
    #40

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