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S4 Exhaust Valve tweak

Thundercliffe81 May 21, 2017

  1. SRB93

    SRB93 S5 B9 Coupe - Glacier White

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    What a sleeper! Looks awesome with the RS Exhausts.
     
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  3. Keef

    Keef Registered User

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    Always been a fan of ovals! Love it
    Right colour car as well !!
     
  4. Thundercliffe81

    Thundercliffe81 Registered User

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    I feel like I've learned so much and purged so much at the same time reading this Any sound clips?


    Sent from my iPhone using Tapatalk
     
  5. SMI77

    SMI77 Australia

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    Well, also written for any visitors, incl Aussies that I know come here, that contemplate single tips (not necessarily RS style) or maybe want to fit Akrapovic carbon quad tips.
    Sound clips? Thank you, but I am not anywhere technical enough. Will work on it though, which will give it time to settle in.

    This is an excerpt from BE's website that may be of interest:-

    Better Flow – More Go
    Exhaust systems are fitted to remove hot, noxious exhaust gases from your engine, reduce engine noise and reduce exhaust emissions. While the factory-fitted exhaust system on your tow vehicle may perform reasonably well, there are usually significant benefits to be gained by replacing it with an after-market exhaust system.

    Most argue that the key to this improvement is to reduce exhaust back pressure, usually achieved by using larger-diameter tubing and free-flow mufflers. However, what’s actually required is to minimize the resistance to gas flow in order to keep the exhaust gas flowing as quickly as possible so that the burnt gases are efficiently extracted from the engine.

    This means that the saying ‘bigger is better’ is not always the case. In fact, the optimum diameter of the exhaust tubing varies according to the amount of exhaust gas being produced, which depends upon engine RPM and load. While this means that it’s not possible to design an exhaust system that works perfectly under all engine conditions, it is possible to design a system that performs significantly better than the original equipment.

    Beaudesert Exhaust is one aftermarket supplier that really understands exhaust systems and can custom-make a system for just about any internal combustion engine. Beaudesert Exhaust has an edge on most of the com- petition because of its long experience in manufacturing mandrel-bent tubing.

    Most exhaust system piping is shaped using hydraulic presses, which has the unfortunate effect of reducing the pipe diameter on all bends, making it harder for the engine to get rid of the exhaust gas.

    By comparison, mandrel bending preserves the original pipe diameter throughout the bend and therefore does not have this problem. The way it works is that the pipe is prevented from collapsing on itself while being bent by the mandrel, which is inserted inside the pipe.

    Quality mandrel benders are unmatched in being able to produce flawless bends quickly and with minimal distortion of the tube. “When looking at a normal bent piece of tube,” business founder Brian Parker explains, “the wall on the outside of the bend is stretched and thinned while the inside wall is compressed and becomes thicker. Our CNC benders are capable of factoring in the bend elongation and are able to maintain a uniform thickness of the tube throughout the curve. This not only keeps the tube diameter the same along the entire length of pipe, but the wall thickness stays constant too.”
     
  6. SRB93

    SRB93 S5 B9 Coupe - Glacier White

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    If you have an instagram or some sort of social media, upload a video to that and plonk the link in this thread (Y)
     
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  7. SMI77

    SMI77 Australia

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    ...errr, I only have a basic phone and do not do texts,tweet,myface, instagram or anything like that.
     
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  8. Thundercliffe81

    Thundercliffe81 Registered User

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    Hero Unplugged haha.


    Sent from my iPhone using Tapatalk
     
  9. SRB93

    SRB93 S5 B9 Coupe - Glacier White

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    You sound like my dad :D We can just imagine.... or you could kindly ask the technically able?
     
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  10. Keef

    Keef Registered User

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    Thundercliffe81 likes this.
  11. Boosted_Six

    Boosted_Six Registered User

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    I'm going to give this a go too. I would only go so far as disconnecting the exhaust box in the bottom of the picture (valve blocking off the 2nd route altogether) though. The effect of opening the valve on just the 2nd tail pipe on the open route looks minimal.
     
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  13. Thundercliffe81

    Thundercliffe81 Registered User

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    Really good this. Not too expensive mate. £2k in the south.


    Sent from my iPhone using Tapatalk
     
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  14. Keef

    Keef Registered User

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    It's not unusual for me to be leaving the house at 04:30-05:00am so would prefer to be able to keep the zorst on the low down till I'm clear of my road and out in the sticks!
    Then crank it up, so a switching option would be best for me
     
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  15. Thundercliffe81

    Thundercliffe81 Registered User

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    If I was keeping the S4, the switch path is the one I'd go for.


    Sent from my iPhone using Tapatalk
     
  16. Robbe

    Robbe Registered User

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  17. Thundercliffe81

    Thundercliffe81 Registered User

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    Keef and Robbe like this.
  18. Boosted_Six

    Boosted_Six Registered User

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    Just another thought on this topic - to stop the soft errors it might be possible to measure the resistance across the pins in the exhaust valve terminal, then proceed to apply a suitable resistor to the pins in the plug going back into the vehicle?
     
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  19. Thundercliffe81

    Thundercliffe81 Registered User

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    By all means show and pics and diagram. I'm a noob.


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  20. cata_adc

    cata_adc Registered User

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    Also unplugged mine
    Maybe a vcds coder will be on with some research in the future :)
     
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  21. zippster

    zippster Registered User

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    :friendly wink:
    I really hope so .. how hard can it be :friendly wink:
     
  22. Jsmills

    Jsmills Registered User

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    Ok, so I’ve been running with the valves unplugged for a week but my ocd has been wanting to plug them back in..

    Today I’ve been running live data logs from odb eleven to see what the valves get upto when plugged in.

    In Eco, Comfort and Auto all in Drive or Sport they are fully variable (all open to valve 1 and or 2 closed) dependant on throttle load, closed ( lists at 90%) to open (10%) don’t know what the percentages relate to but at ignition off they read 35%.. the road speed has no relation to their status, it’s load based..

    Anyway, under Dynamic and Individual (exhaust set to sport) they are also fully variable unless in Sport on gearbox, then they are always open ...

    ok so some will already know that... here is the interesting bit, if you toggle to dynamic or individual after the engine has started, the valves will remain fully open all of the time until the engine is next switched off, this includes the standard drive setting on the gearbox. It reverts back after next restart, but toggling enables again.

    For some this may be preferable to removing the plugs.
     
  23. A12RNX

    A12RNX Registered User

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    That is good to know. Do the valves stay open if you always have in dynamic mode from start up? Same with individual set to sport?

    Thanks.
     
  24. Jsmills

    Jsmills Registered User

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    strangley no... for the valves to stay open, Dynamic or Individual needs to be selected after every startup. If it was already on that setting they default to variable flaps.
     
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  25. Daggerit

    Daggerit Registered User

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    But if you start the car in Dynamic (and it has the variable flaps) and then stick the transmission in 'S', do they open as if you'd selected the mode? And then stay open if you go into 'D' again?
     
  26. Jsmills

    Jsmills Registered User

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    So when you go to ‘S’ it will open the flaps at all times but they return to variable when it goes back to drive. Going to ‘s’ doesn’t trigger the always open flaps like toggling the mode does. Strange but I tested a few times.
     
  27. Daggerit

    Daggerit Registered User

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    Even when you’ve started the car in dynamic or individual? Nice to know because I figured it would keep them open!


    Sent from my iPhone using Tapatalk
     
  28. Jsmills

    Jsmills Registered User

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    Haha well you’d think so but no.

    Either run it in ‘S’ on gearbox
    Or
    Cycle to dynamic or individual after starting.

    Anything else is variable flaps.
     
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  29. bkusk12

    bkusk12 Registered User

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    After all this time, is this still true? To be clear....all you have to do is start the car (with the valves plugged in) then change drive mode to dynamic and then you can switch back to comfort and all four valves will remain open until you shut the car off next?
     
  30. Jsmills

    Jsmills Registered User

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    Sorry, it is only fully open in dynamic or individual (with exhaust set to sport) and only when this mode is selected after starting the engine.
     
  31. Tony Resta

    Tony Resta Registered User

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    I finally got around to doing this on my S5 last night. What a sweat! Took 5 minutes on one plug, and a good hour on the other, my fingers are still hurting!

    I'm happy to report that everything works fine and the sound has very much improved in the low RPM range. The idle sound is also better and last but not least, revving whilst in park-mode produces some very sexy pops and crackles :D

    Haven't tried the motorway yet. Definitely recommend this though. One tip would be to raise the car if possible, I did it all whilst lying on the floor with a few centimetres of space between my face and the exhausts, and I came out quite dirty!
     
    WesT-gefül likes this.
  32. RichardMMM

    RichardMMM Registered User

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    It doesn't give you anything different to switching to Dynamic or Individual after starting the car (for individual that assumes you've set engine sound to sport). I had them unplugged for a while but I prefer to be able to control the valves and I often just switch modes as soon as I start the car. It doesn't remember the last setting unfortunately even though it may say it is still in Dynamic.
     
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  34. Javbomb

    Javbomb Registered User

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    Just be aware that its possible that if you unplug your valves that you will lose power due to the soft error codes and the car pulling timing to protect the engine, it was 100% the case on RS3's and dyno proven, no dyno test for that on this car yet though, but be aware its possible.

    I unplugged the valves for a couple days, and didn't find it much of a difference if any than just running Dynamic S mode. The RS3 I used to have valve terminator plugs and ran them like that for the whole time I owned the car.
     
  35. Boosted_Six

    Boosted_Six Registered User

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    I just unplugged the drivers side one. S mode opens the other side as before. Was too droney at 70+ otherwise.

    I don't have any codes according to Carista.
     
  36. Tony Resta

    Tony Resta Registered User

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    Two quick clips of the exhaust sound after having unplugged the valves. It's no RS tone but I feel it's much better than before, and has a nice deep sound during low revs.



     
    mister.c. likes this.
  37. JulienG

    JulienG Registered User

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    On my S4 B9 2018, the exhaust sound changes a lot if my in Drive or Sport on the "gearbox" lever while being in Individual mode with Dynamic exhaust mode in MMI.
    Have you also notice the impact of the gearbox mode ?

    Thanks
     

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