Active Exhaust

From 3SI Wiki

Description of Active Exhaust system

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The Active Exhaust system allows the driver to choose between "Sport" and "Tour" modes.

1) The "Sport" mode produces lower restriction to the engine, and will be noticably louder at lower RPMs.

2) The "Tour" mode is quieter . . . up until approx 3000/3500 rpm at which time the computer opens the changeover valve, (temporarily switching to sport mode).

If the dash switch is set to "Sport", then the changeover valve at large inlet to muffler is pulled open by the actuator motor and cable. All of the exhaust gases flow basically straight thru the muffler and exits on driver's side.

If the dash switch is set to "Tour" then the actuator motor releases tension on the cable, the spring will rotate the valve is closed. . . . This forces exhaust gases thru smaller tubing, baffles etc. in the muffler. Approx half of the gases will exit on driver side, and half will exit the passenger side.

If the dash switch is set to Sport, then the valve is held open by the actuator motor and cable at all times. If the dash switch is set to Tour, then the valve will close and open depending on conditions. The valve will remain in the closed "tour" position, unless one of three conditions occur:

1) the dash switch is set to "Sport",

2) the engine is above 3000/3500 rpm,

3) the engine is turned off.

Some diagrams from manual	Copied from Technical Manual
Cutaway of Muffler, showing internal flow, Sport	Cutaway of Muffler, showing internal flow, Sport
Cutaway of Muffler, showing internal flow, Tour	Cutaway of Muffler, showing internal flow, Tour
Photo taken in cold weather to illustrate the exhaust flow in Sport mode. High idle.	Exhaust in Sport mode
Photo taken in cold weather to illustrate the exhaust flow in Sport mode. Low idle.	Exhaust in Tour mode
Photo taken with driver rear wheel removed.	Valve plate position - Sport
Same as above, but tour mode.	Valve plate position - Tour