Updated Boost Control/WGFV Diagram

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  • prj
    S2Forum Zealot
    • Mar 2010
    • 6308
    • Country: Estonia

    #16
    Originally posted by driftin jo
    Wrong, there might be a little gas pushing past the wast gate but not enough to stop out of control spool of the turbo, as said above the only thing stopping unlimited boost is the ECU cutting the fuel pump. If you don't believe it then hard wire you fuel pump and try it, you will get 2.5 bar, just before your con rods are turned into bananas.
    ECU does not cut pump, it cuts injectors.
    http://tuner.ee - http://www.facebook.com/tuner.ee

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    • driftin jo
      S2Forum Fiend
      • Sep 2007
      • 2222
      • Country: United Kingdom

      #17
      Originally posted by prj
      ECU does not cut pump, it cuts injectors.
      I stand corrected.

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      • UrS4boy
        S2Forum Obsessed
        • Feb 2006
        • 11859
        • Country: Canada

        #18
        Originally posted by cooperquattro
        not strictly true!!!if there is no hose on the w/g then the opening point will be spring pressure,meaning the exxhaust gas will open the valve at the given pressure,NOT give unlimited boost
        Nope. The spring keeps the valve CLOSED. Without pressure to the lower chamber there is NOTHING to open the WG valve.
        RS2'd 93 UrS4 5 spd sedan
        94 UrS4 V8 6 spd manual avant

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        • UrS4boy
          S2Forum Obsessed
          • Feb 2006
          • 11859
          • Country: Canada

          #19
          Originally posted by Jamo
          Having done this as a test I can tell you you get boost until ecu cut. .... it will only open at spring pressure with a boost source to the lower chamber
          ^^This^^
          RS2'd 93 UrS4 5 spd sedan
          94 UrS4 V8 6 spd manual avant

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          • prj
            S2Forum Zealot
            • Mar 2010
            • 6308
            • Country: Estonia

            #20
            Originally posted by UrS4boy
            Nope. The spring keeps the valve CLOSED. Without pressure to the lower chamber there is NOTHING to open the WG valve.
            There is actually.
            Exhaust gas pressure does press on it from below, but that pressure is fairly negligible, because of the way it's oriented.
            But if you would take the spring out for example, then the gases would push it open and you'd get no boost. Or if you would fit a 0.1 bar spring, it'd also push it open with just the pressure of the exhaust.

            P.S. I know this is not very relevant, as no one is running anything less than 0.4 bar spring, but I thought it's correct to point out.
            http://tuner.ee - http://www.facebook.com/tuner.ee

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            • UrS4boy
              S2Forum Obsessed
              • Feb 2006
              • 11859
              • Country: Canada

              #21
              Originally posted by Jamo
              Agree wastegate is wrong way around as gas come in under the valve not through the side as shown in diagram
              Does this "new" diagram work better/do your head in less?

              RS2'd 93 UrS4 5 spd sedan
              94 UrS4 V8 6 spd manual avant

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