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  • EXDOS Exhaust silencer mod

    Sorry, but this posting is no longer available.
    /// Exdos ///
    "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

  • #2
    LOL - 10/10 for effort Exdos!! You really go to town on these things don't you :wink:

    I think you will certainly get a change in volume if you bypass a whole section, probably too loud as you suspect. I think though you could make some very interesting exhaust notes by playing around with the 'tuned collars', which is probably worth doing just on it's own.

    However if it's a performace gain you are after I will be honest and say I don't think you ever get anything worthwhile.

    You have to remember that there is a cat or two before the rear silencer and the restriction that this causes will more than likely overweigh anything you do with the silencer.

    Some backpressure in a N/A is required to help 'scavenge' the spent gasses out of the cylinders. The scavenging is a resonant effect influenced by the design of the exhaust manifold (diameter, shape and length) and the back pressure downstream of it (the majority of which is from the cat).

    Even a professional aftermarket back box will rarely give you more power (despite what the manufacturers claim) but they can alter the power curve a little by shifting resonant frequencies as explained above. The effect is more noticeable with lower cat cell denisties.

    I think you should concentrate on just getting the best sound that you can and forget everything else - I wouldn't be worried about losing torque low down. Nice work BTW 8)
    Black 02 reg S54 M Roadster

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    • #3
      Re: Exhaust silencer mod

      Originally posted by exdos

      If it is suggested that what I have done will cause reduction in power at low revs due to lack of back pressure, then I shall make a weighted flap on a hinge which will be attached to the mouth of the inlet pipe in the final chamber (similar to those seen on tractors) so that when the flow of exhaust gases increases the pressure in the inlet pipe will lift the flap so that the inlet pipe is completely open.
      my e36 328sport had one of these flap/butterflys that was operated by a vacuum. have a look on e36coupe.com for more info. but IIRC it was only there to increase pressure at low revs... a trip to a breakers may be on...

      good work fella.

      HTH

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      • #4
        ...
        /// Exdos ///
        "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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        • #5
          Originally posted by exdos
          I did consider the possibilty of fitting an automatic butterfly to regulate the exhausts similar to the one for the E36 328 sport, which opens the butterfly at around 2750 rpm, but when I thought about it, apart from pootling around in traffic, I very rarely have the engine operating below 3000rpm, so I don't really see the point in making any effort to source and buy the parts plus all the ancilliary work in fiiting it all together.
          good point, sounds like you are from my school of engineering, "if it ain't broke, don't fix it!"

          very interested on hearing the results of the exdos mod take 2.

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          • #6
            Exdos Exhaust mod

            ...
            /// Exdos ///
            "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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            • #7
              ...
              /// Exdos ///
              "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

              Comment


              • #8
                Looks good - is the welding stainless steel too?

                What wheels do you have btw?

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                • #9
                  ...
                  /// Exdos ///
                  "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                  Comment


                  • #10
                    Originally posted by exdos
                    Originally posted by c_w
                    Looks good - is the welding stainless steel too?

                    What wheels do you have btw?
                    Yes, it's all stainless welding done with a MIG and proper shielding gas.

                    Wheels are BBS RX IIs
                    Well done John

                    can I spy a mod from the Exdos aerodynamic range :?: :wink:
                    Ex 'V3RY M - MCoupe track monster'
                    New toys

                    Porsche widebody project

                    Cayenne Diesel

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                    • #11
                      ...
                      /// Exdos ///
                      "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

                      Comment


                      • #12
                        Originally posted by exdos
                        Originally posted by Lee

                        can I spy a mod from the Exdos aerodynamic range :?: :wink:
                        Yes. Here at Exdos Developments, we have been very busy over the past 12 months :wink:

                        I'm now running out of ideas for further mods :cry:
                        John, I am sure you will come up with something, Personally I would like you to develop a better ducting system for the passage of air to the induction system/airbox!

                        I would like to order the Exdos rear aerodynamic mod, Please can you pm me a price?

                        Thanks

                        Lee
                        Ex 'V3RY M - MCoupe track monster'
                        New toys

                        Porsche widebody project

                        Cayenne Diesel

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                        • #13
                          Would be intrested to hear the difference with this mod.

                          10/10 for effort!
                          Ex S54 - She has gone....

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                          • #14
                            Originally posted by exdos
                            Yes. Here at Exdos Developments, we have been very busy over the past 12 months :wink:

                            I'm now running out of ideas for further mods :cry:

                            increased bore throttle bodies (or better flow)?
                            more efficient brake cooling

                            why not get really into it and get the laptop plugged in and work out how to remap the ignition! that will keep you busy for a while!

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                            • #15
                              ...
                              /// Exdos ///
                              "Men who try the impossible and fail spectacularly are infinitely superior to those who reach for nothing and succeed" --Napoleon Bonapart

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