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  • #31
    Originally posted by S2central.net View Post
    Yes - the WGFV is nothing more than a solenoid that is driven by the ECU... The duty cycle is provided by ECU software. You are right to say that any WGFV would do the job - as long as it responds quickly to duty cycle modulation and is reliable (doesn't stick) and robust enough in the hot engine bay to keep operating.

    AFAIK - the ECU uses the nominal amount of duty cycle set in the software to achieve target boost pressure for the prevailing conditions (load and demand). It has the ability to adapt the duty cycle to cater for aging, thermals and such like... I don't know how much it can adapt by, but there are fault codes raised by the ECU if it detects excessive boost (unable to reduce duty cycle to achieve target) and for a failure to achieve the target boost if duty cycle cannot be increased within adaptation limits.

    Something that occurred to me today about these dual port WG configurations is that the upper chamber MUST remain airtight for those to work properly. Note that many a wastegate cap that has been 'frankensteined' with an adjustable screw will not have an airtight upper chamber - even though the membrane to the lower chamber is a perfectly airtight seal.

    As time permits I will do some dabbling with different springs and WG topology and make ECU tweaks to seek the best from them. I'll also test that turbosmart solenoid as well for kicks.
    now that is food for thought, my cap was pre frankensteined by previous owner need to see if it leaks

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    • #32
      Good wadge of loctite / araldite down there will sort it out.
      Paul Nugent
      Webmaster http://S2central.net
      Administrator http://S2forum.com

      1994 S2 Coupe ABY - aka Project Lazarus
      2001 A6 allroad 2.5TDi - family tank
      2003 S4 Avant 4.2 V8 - daily burble

      Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

      There are only 10 kinds of people that understand binary - those that do, and those that don't

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      • #33
        I have a screw and a nut there, but I'm pretty sure it is fairly airtight!

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        • #34
          'fairly airtight' is fine if running with uppermost chamber at ambient pressure... but if using funky WGFV topology that applies control pressure to the uppermost chamber then its bad news - as control pressure might be leaking past the frankenthreads. Only way to be sure is vacuum applied to upper control port - if its airtight then you are good.
          Paul Nugent
          Webmaster http://S2central.net
          Administrator http://S2forum.com

          1994 S2 Coupe ABY - aka Project Lazarus
          2001 A6 allroad 2.5TDi - family tank
          2003 S4 Avant 4.2 V8 - daily burble

          Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

          There are only 10 kinds of people that understand binary - those that do, and those that don't

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          • #35
            Originally posted by A80Avant View Post
            I have a screw and a nut there, but I'm pretty sure it is fairly airtight!
            If it is leaking when you test it just rap some PTFE tape round the threads that will get it gas tight.

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            • #36
              I was going to post i'm going to PTFE the threads and locktite it as I am using the upper chamber fulltime

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              • #37
                I will not be fitting locktite as i want to be able to fiddle with the spring a bit.

                Here the setup. Its a large screw and nut, which are very tightly bolted. For the piece of mind but also a small test, i will add some PTFE tape that i have there to see if im going to have any higher boost or any spikes there. If i am loosing boost pressure, then with VEMS all i would get is a spike,as the PID config, will eventually push the N75 to reach the target boost. I will let you know once i have logs and tests done.

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                • #38
                  Originally posted by A80Avant View Post
                  I will not be fitting locktite as i want to be able to fiddle with the spring a bit.[/IMG]
                  You get different grades of locktite, blue is good for stuff you want to take apart easily (with tools) but will not vibrate apart, I don't know how well it deals with heat though?
                  Current-2004 Impreza PPP wagon

                  Sold-92 3B coupe-RS2+, 996s, konis, rear torsen, forged rods........
                  Sold ABY-stock

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                  • #39
                    The hoses and tolerances are so small in there, that the leak isn't going to do much at all, even if it's there.
                    I mean, I am all for everything working properly, but it's not really going to leak enough to make a huge difference.
                    http://tuner.ee - http://www.facebook.com/tuner.ee

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                    • #40
                      PRJ what is the downside of using mechanical boost?
                      Audi Nut!!!

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                      • #41
                        i see

                        ill try some PTFE tape anyway since it is mentioned and i have it as a spare... that when i have the car back....

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                        • #42
                          Originally posted by Tonks4x4 View Post
                          PRJ what is the downside of using mechanical boost?
                          http://tuner.ee - http://www.facebook.com/tuner.ee

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                          • #43
                            I ran it on my old 90 Quattro B2 it ran 14psi on a pressure relief valve. So had no wastegate creep at all and boosted 14psi from about 2000rpm to 6000 approx before the turbo ran out of power.
                            It was good on AFR
                            And I did not have any bad effect but people say it is not good to do
                            Audi Nut!!!

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