Overboosting.... Help im running out of ideas

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  • S2central.net
    Retired OG Mod
    • Jul 2003
    • 16590
    • Country: Northern Ireland

    #16
    A long shot maybe - with the very free flowing exhaust that you have Greg - could the turbo be overspinning I wonder and causing excessive boost ?

    Was the car mapped with this exhaust system or not ?
    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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    • Mihnea
      S2Forum Extremist
      • Jul 2003
      • 1288
      • Home: Belgium Current: United Kingdom

      #17
      Originally posted by S2central.net
      A long shot maybe - with the very free flowing exhaust that you have Greg - could the turbo be overspinning I wonder and causing excessive boost ?

      Was the car mapped with this exhaust system or not ?

      Good point Paul, the answer is "not", the car has been remapped with the stock exahust, including cats and standard DP....

      Greg, can u make it to Doug's this weekend or not? Forget the speedo/mileage stuff, we'll sort that out for you

      Cheers,

      Mihnea, soon to prepare stuff before leaving
      '98 Silver Grey 2.7T S4, dual 2.75" turbo back exhaust with no cats, FMIC, BIG injectors, 10 Bar motorsport fuel pump, modded RS4 turbos, tubular exhaust manifolds, custom intakes, RS4 MAF, Bilstein PSS9, H&R ARBs, 19" BBS CH, custom remap, 511 BHP/505ft-lbs

      www.MRCTuning.com
      info@MRCTuning.com
      Workshop Directions

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      • Doug_RS2
        S2Forum Possessed
        • Jul 2003
        • 3847
        • Home: Scotland Current: England

        #18
        yeah - get up here Greg - If you are running 2 bar boost I want to see how yours feels compared to mine running 2 bar. There will be a few cars here so you can swap bits over if you are really stuck.
        S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8

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        • S2central.net
          Retired OG Mod
          • Jul 2003
          • 16590
          • Country: Northern Ireland

          #19
          Ahhh see you can tell I have been doing more homework this week huh !

          Been travelling with work this week and have had some chance to get my head round the wonderful world of turbochargers. I have also drafted a paper on 'how to read compressor maps' for us along with some useful calculators in Excel for compressor selection and estimation of air temperatures. Ohhh its good stuff - based on some reference info from Meister Corky Bell, Messrs Garrett, KKK and a few other sites of interest. I'll post it tomorrow when I get the graphics sorted and then it can be reviewed and improved.

          If I get really organised I shall create a web version of the calculators so that y'all can play with various values.

          If my calculations are correct, I can see a GT30R application on the S2 with the right intercooler that produces inlet air temp below 40 degrees C with 1.8bar boost on the redline.


          Paul

          PS - It was something in Corky's book that triggered my thoughts on the turbine overspinning as a result of much reduced back pressure from the exhaust.
          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

          Comment

          • Greg_S
            Administrator
            • Jul 2003
            • 12430
            • Country: United Kingdom

            #20
            Doug, Mihnea. Would love to come up this weekend but don't think I can afford to this month with petrol and stuff too because got hol coming up next month. I will let you know later on.

            Im gonna try the stock WG spring later as Mihnea suggested and will let you know.

            Greg
            Greg

            S2Forum.com Administrator & Webmaster

            '93 Coupe with a few tweeks

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            • Doug_RS2
              S2Forum Possessed
              • Jul 2003
              • 3847
              • Home: Scotland Current: England

              #21
              Greg - if you run sensibly you can get up on 1 tank and home on another tank ! I did it during the week!

              It defo sounds like your car needs remapped for your exhaust and non leaky hoses - no way around that.

              I finished mapping mine - well over 400bhp!
              S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8

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              • Greg_S
                Administrator
                • Jul 2003
                • 12430
                • Country: United Kingdom

                #22
                Dont be saying things like that to me now. Mihnea, realistically what power can the standard rods run?
                Greg

                S2Forum.com Administrator & Webmaster

                '93 Coupe with a few tweeks

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                • Greg_S
                  Administrator
                  • Jul 2003
                  • 12430
                  • Country: United Kingdom

                  #23
                  Just been out to try changing WG spring and it def isnt to be this eve, first i dropped a nut into undertray then the WG perch so im gonna leave it till the morning and do it properly now.

                  greg
                  Greg

                  S2Forum.com Administrator & Webmaster

                  '93 Coupe with a few tweeks

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                  • Greg_S
                    Administrator
                    • Jul 2003
                    • 12430
                    • Country: United Kingdom

                    #24
                    ITS FIXED im a very happy chap now. Changed the WG spring back and set the mechanical boost to 0.6 - 0.7 Bar and then connected WGFV back up and its fine again. Replaced my original WGFV from the new one that was fitted and thats fine too.

                    So car is back and running nicely for now.

                    Greg
                    Greg

                    S2Forum.com Administrator & Webmaster

                    '93 Coupe with a few tweeks

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                    • Beetie
                      S2Forum Extremist
                      • Oct 2003
                      • 1517
                      • Country: England

                      #25
                      Originally posted by Greg_S
                      ITS FIXED im a very happy chap now. Changed the WG spring back and set the mechanical boost to 0.6 - 0.7 Bar and then connected WGFV back up and its fine again. Replaced my original WGFV from the new one that was fitted and thats fine too.

                      So car is back and running nicely for now.

                      Greg
                      I was going to ask if i could have some of your overboost as mine still hasn't got any!
                      Was a '93 3B, Dont ask now tho......

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                      • Greg_S
                        Administrator
                        • Jul 2003
                        • 12430
                        • Country: United Kingdom

                        #26
                        LOL, still trying to track down the the problem at the min?

                        Greg
                        Greg

                        S2Forum.com Administrator & Webmaster

                        '93 Coupe with a few tweeks

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                        • Dr H
                          S2Forum Extremist
                          • Jul 2003
                          • 1175
                          • Country: England

                          #27
                          Originally posted by Greg_S
                          ITS FIXED im a very happy chap now. Changed the WG spring back and set the mechanical boost to 0.6 - 0.7 Bar and then connected WGFV back up and its fine again. Replaced my original WGFV from the new one that was fitted and thats fine too.

                          So car is back and running nicely for now.

                          Greg
                          How do you get that much mechanical boost? With the standard spring really really screwed down mine only makes just under 0.5 bar

                          Paul N siad his only makes 0.4 bar - I think.
                          Ex 1994 Avant - now driving a Lotus 340r

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                          • jubjub
                            S2Forum Extremist
                            • Nov 2003
                            • 1239
                            • Country: England

                            #28
                            I bet you have a big again.....Greg-what way round is your WGFV fitted?

                            Comment

                            • Greg_S
                              Administrator
                              • Jul 2003
                              • 12430
                              • Country: United Kingdom

                              #29
                              I noticed that today too Jub Jub. On the 3B's it has the little white dot on the otherside to the ABY ones.

                              Its mounted with the long pipe of WGFV into intake pipe, the one opposite to WG and one out of bottom of WGFV to turbo compressor housing.

                              Greg
                              Greg

                              S2Forum.com Administrator & Webmaster

                              '93 Coupe with a few tweeks

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                              • newsh
                                S2Forum Obsessed
                                • Aug 2003
                                • 16226
                                • Country: United Kingdom

                                #30
                                Originally posted by Greg_S
                                Just been out to try changing WG spring and it def isnt to be this eve, first i dropped a nut into undertray then the WG perch so im gonna leave it till the morning and do it properly now.

                                greg
                                Hmm, those nice shiney nuts?

                                Glad you got it sorted Greg!

                                S2 Coupe 3B Project


                                Ur quattro restoration

                                S2 Avant

                                Boost is the new rock and roll!
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