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S4 Exhaust Valve tweak

Thundercliffe81 May 21, 2017

  1. Greg Goulding

    Greg Goulding Registered User

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    Sounds like I know what I'm doing next weekend! Glad it's not just me that has dirty pipes!


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  3. Thundercliffe81

    Thundercliffe81 Registered User

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    I'll refrain from the obvious joke! Ugh, you're right. If you guys seen my car, you'd string me up. The sycamore tree has gone full ****** and my entire car is sticky like glue and full of bird muck. Well, goose poo to be specific. And it's killing me haha. Cleaning this weekend.


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    Last edited: May 22, 2017
  4. Thundercliffe81

    Thundercliffe81 Registered User

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    Cold start video didn't record sound this morning. Think my phone memory is full. Will do tomorrow but trip to work sounds very good. Certainly enough difference for just keeping valves open anyway. As I said low rev burble and grunt with much louder and deeper bottom end pulling away fast.


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  5. 81llyh

    81llyh Registered User

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    Where's the videos??? :D
     
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  6. Thundercliffe81

    Thundercliffe81 Registered User

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    I'm on it this morning. Been a very busy week bud. We thank you for your patience


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  7. Keef

    Keef Registered User

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    @Thundercliffe81 looks like your post has found its way to the A5/S5 section...

    I'm really tempted to do this, but need by zorst to be even quieter in the mornings on cold start.
    Twice last week I was on the road at 04:30 and saw my neighbors curtains twitching lol, he remarked when I first got
    the car, "its louder than the last one"

    I know you can get separate wireless controller kits for the valves on Akrapovič systems, I wonder if a wireless kit could be installed on our systems?
     
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  8. Thundercliffe81

    Thundercliffe81 Registered User

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    Screw em!! How's it got all the way over there?




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  9. EddieRS3

    EddieRS3 Registered User

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    Sounds good mate !

    Quite nice to see all 4 tailpipes in use.

    I need to find a way of getting more pops from the exhaust
     
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  10. Thundercliffe81

    Thundercliffe81 Registered User

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    I don't think a wireless kit exists but surely it could made?


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  11. Thundercliffe81

    Thundercliffe81 Registered User

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    Get them things we use to have as kids. The ones you throw on the floor that go bang. Haha


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  13. DG555

    DG555 Registered User

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    Can you do some warmed up tests to compare to this? I recorded this yesterday with a crappy GoPro Hero+ but it's pretty close to the way it sounds. This is with all valves in place and unmodified.

     
  14. Thundercliffe81

    Thundercliffe81 Registered User

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    That in dynamic? Getting a bit of background noise. I'd have to incorporate the services of my lady (no jokes) and trottle off somewhere to get some rev shots. My neighbours wouod green light me at mine I'll see what I can do. It's definitely louder now.


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  15. R.A.G

    R.A.G Registered User

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    That might have been me!

    Thanks for taking the lead on this, I've done it myself now, and although subtle, it's a nice improvement to the depth and tone.

    It would be great if someone smarter than me can work out a way to code them open, or trick the car into ignoring the valves somehow, I'd be happier with that than physically leaving them unplugged long term.
     
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  16. Thundercliffe81

    Thundercliffe81 Registered User

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    Yeah I feel you on that note. I've taped mine up pretty well and cable tied up high so hopefully zero moisture gets in there. I need a fellow Audi man in the North with VCDS capability to wipe the slate clean before my first service. It's subtle I agree but it's definitely an improvement. Waiting to see how @EddieRS3 Gets on now with his mod in July!


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  17. 81llyh

    81llyh Registered User

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    I have vcds where abouts are you?
     
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  18. Thundercliffe81

    Thundercliffe81 Registered User

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    West Yorkshire.


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  19. 81llyh

    81llyh Registered User

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    I'm in West Yorkshire too :tearsofjoy:
     
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  20. Thundercliffe81

    Thundercliffe81 Registered User

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    Happy days. That's great to know. I'm due in in 9000 miles. Ok to hit you up then?


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  21. 81llyh

    81llyh Registered User

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    That's fine..what is it you want doing?
     
  22. Thundercliffe81

    Thundercliffe81 Registered User

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    It'll just be the fault codes removing before the service for unplugging the electronic valve control.


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  23. DG555

    DG555 Registered User

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    Yes it's in dynamic. If the system operates like VW Ines then the valves should remain closed unless it's over 40mph and a certain RPM. This is to comply with EU noise regulations. Mine certainly shuts closed when stationary regardless of driver mode.
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  24. Thundercliffe81

    Thundercliffe81 Registered User

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    Yeah mine did before. Got to rev it hard to get flaps open. I wonder what the B9 RS4 is going to sound like


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  25. DG555

    DG555 Registered User

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    Marketing will make sure it sounds like the B5 I'm sure :)
     
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  26. Thundercliffe81

    Thundercliffe81 Registered User

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    That's what I'm scared of haha.


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  27. TripleD

    TripleD Audi S4 Avant Owner

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    Have been following this thread, and thought I'd add my completely unresearched opinion for what it's (probably not) worth.

    It's been mentioned that the exhaust valves are closed in a certain rev band, isn't this done to generate some kind of back pressure until the turbo is spooling enough that it then needs to get rid of the gases quicker, in whihc time they are opened?
    From memory and younger days a lot of people started changing exhausts to bigger ones with less boxes, but it was found the turbo pressure had to increased and engines started to go bang quickly (RS Turbos).
    So the question really comes down to how does this mod actually effect the engine and turbo rather than just increasing the noise? because if it's having to up the turbo pressure to account for the open exhaust, and as mentioned it's logged that the valves are disabled, that's your warranty out of the window, and a very expensive engine replacement in the worst case, or a turbo replacement as the seals are blown.

    Like I said, maybe fine, but also maybe worth some kind of test to see how the turbo pressure changes. Also depends on the length of ownership I suppose ;)
     
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  28. Thundercliffe81

    Thundercliffe81 Registered User

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    Very good point that. I've heard on the S3 it's not an issue but we got anybody in the know that has anything gospel on this?

    Cheers


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  29. EddieRS3

    EddieRS3 Registered User

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    As far as I was aware the valves are purely there to altar sound rather than turbo pressure.

    Certainly is the case with BMW but not sure on Audi if I'm honest. However, there are people running complete decat systems with a straight pipe and had no issues. Not sure with this new engine though !
     
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  30. DG555

    DG555 Registered User

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    The flap is there only for noise reduction by EU regulations below 40mph. The R32 had the same thing and was without a turbo charger. A few owners claimed back pressure changes but nothing was ever proven and I highly doubt it'd make any difference.
     
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  31. DeanoC

    DeanoC Well-Known Member VCDS Map User

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    Worth noting my RS lost 12lbft torque having the valves open below 3k rpm.

    Probably does not tramslate to the S4 as that is turbo but worth checking

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  32. TripleD

    TripleD Audi S4 Avant Owner

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    Assuming these guys have had some kind of remap as well in order to compensate for the difference in the exhaust flow? which would mean the turbo pressure sensors would accomodate the throughput.

    I suppose the just for noise control makes sense as the flaps are sitting on the tailpipes and not closer to the engine, was just a thought I had while waiting for my emails to open this morning. I'm no mechanic so can easily be proved wrong :)
     
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  34. Thundercliffe81

    Thundercliffe81 Registered User

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    Holy ****!! The RS4 needed all the torque it could get! That's a lot!


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  35. Thundercliffe81

    Thundercliffe81 Registered User

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    Cheers guys for thoughts on this.


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  36. Daggerit

    Daggerit Registered User

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    The physics is that the back pressure is not 'tuned' for turbo cars versus NA cars as they don't require it for scavenging from the cylinders on the exhaust stroke. The exhaust already has back pressure from the turbo and so in theory you should have as free-flowing of an exhaust as possible after the turbo for best gains. :)

    Lots of YouTube stuff about it I'm sure.
     
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  37. R.A.G

    R.A.G Registered User

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    It is indeed a very valid point that I considered before opening mine up permenantly, I'm certainly no mechanic either but my logic is, if the car leaves both valves open in Dynamic and Sport auto (which I believe it does), it surely can't be causing any drop in torque or doing the engine any harm, I genuinely think as others have stated it's an EU noise reg thing, and for owners who want a quieter exhaust note!
     
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  38. Thundercliffe81

    Thundercliffe81 Registered User

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    It's an excellent mod I think. Just that little bit extra.


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  39. Ridders71

    Ridders71 Registered User

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    Hi all.

    I am a new S5 owner ( sorry, don't kick me out..) and have been following this with interest. I am not wanting to mod my car, but I am wanting to understand better how the exhaust valves function in the different drive select modes, on cold start up and when 'sport' mode is engaged with the gear selector.

    What I think I have learned is that all valves open in both dynamic, but only over 40 mph and a certain rev level? Selecting sport in any drive mode does the same with the exhaust as being in dynamic?
     
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  40. Thundercliffe81

    Thundercliffe81 Registered User

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    Evening. Liking the car?

    Yes, I believe that is all true. Cold start on closed valves. Only open at certain rev range. This mod just adds more low down grumble/burble and louder sound at lower speeds. I'm not experiencing any drone at motorway speeds.


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  41. R.A.G

    R.A.G Registered User

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    Totally agree mate, I've driven 200+ miles today and there's no noticeable downside to my ears, no motorway drone and just much better sounding low down and under load.

    My exhaust tip OCD is also calming down as all four tips has a light amount of soot rather than just the one being caked in it (I'm sad I know!)
     
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  42. Thundercliffe81

    Thundercliffe81 Registered User

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    This is an acceptable (and empathised) level of sadness buddy I'm sure some better mods will sound great. I'm thinking @EddieRS3 here, looking forward to hearing that.


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  43. Ridders71

    Ridders71 Registered User

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    Yes thanks, loving the car. I have some pics i the A5 forum, I won't repeat them here, I will no doubt be breaking forum rules lol. Only got it last week, still taking it relatively easy!

    So, no difference in exhaust behaviour between dynamic and "sport"? And in Individual drive select it gives option to set 'engine noise' - I am guessing this is actually exhaust noise and essentially sets it to behave as though in dynamic.

    Sorry for all the questions! Like others, having only one exhaust get dirty I don't like - especially. It makes the other 3 tailpipes appear 'fake'
     
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