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    Cool Carrera GT Exhaust System Feature

    I had the opportunity to visit the Atlanta service training center for Porsche Cars North America last week. I was there to "try on" the wide option seats fitted to the service training CGT in thier classroom/shop.

    I took a few pictures of the car in its dissassembled glory during a very interesting tour of the Carrera GT's finer internal points given by the PCNA training staff.

    The picture below shows two vacuum motors on the exhaust system. Here is how Porsche's "Carrera GT Service Information 2004 Technik Introduction" book (which somehow fell into my possesion) describes their use:

    "Within the final muffler box their is a additional flap-type muffler. This flap mechanism is controlled by two vacuum motors which are installed outside the box. The flap mechanism is used to reduce back pressure and associated increased demand for power from the engine. The control is performed under a mapped reference in the Motronic, via electro-pneumatic changeover valves.

    The exhaust gas flaps are opened from second gear to sixth gear at speeds in excess of 43 mph (70 km/h), and in gears 1st, 2nd, and 3rd at engine speeds in excess of approx. 2,800 rpm, if the air mass flow exceeds a certain threshold. For each gear there is a specific performance curve for flap control stored in the Motronic control unit.

    To check that this flap is functioning correctly there is an external pressure sensor installed on the final muffler. The external pressure sensor is located near the catch for the engine lid. The connection to the pressure measurement port is made with a flexible steel lead with Teflon core. The pressure in the exhaust system is sensed upstream of the main catalytic converter."

    Way cool in geek-ville

    Re: Cool Carrera GT Exhaust System Feature

    Very cool

    Re: Cool Carrera GT Exhaust System Feature

    Very cool. Any other interesting pix from the visit to share?

    Re: Cool Carrera GT Exhaust System Feature

    Very interesting. The VW Golf R32 (240hp AWD) has a similar setup. In fact, the assembly and operation looks/sounds exactly the same. Here is a photo from the R32: (ignore the white clamp)



    What's really cool is, if you clamp off the black vacuum line(s). The valve is always "open" and the car SCREAMS! (This is what's illustrated in the above photo)

    The 360CS also has exhaust bypass valves. However they are a different style (butterfly).

    As a side note, I don't know if any of you have heard the Golf R32's exhaust note but IMO it's one of the best around.

    Re: Cool Carrera GT Exhaust System Feature

    The tech guys in Atlanta took some pains to point out to me that the vacuum motors being attached to the muffler were NOT operating in the same way as the 996 special sound package muffler. The 996 muffler vacuum mechanism was only for sound. The Carrera GT vacuum motor and flap system is used for engine performance.

    Re: Cool Carrera GT Exhaust System Feature

    So which seat did you get? The regular or larger one? Did you go with the standard seat height or down 10 mm? I chose the standard seat for the driver side (10 mm lower) and the wider and higher one for the passenger (easier to get in and out of).

    Re: Cool Carrera GT Exhaust System Feature

    Hi Ben,

    I absolutely went for the wider seat in the low position. "Wider" only means 15 mm more breadth. That's about 0.59 inches of extra hip room. Enough to notice. but not enough to cure a real problem. The wider seat was still snug on my hips, but not too uncomfortable. Just about right for the track, but somewhat confining on the street.

    It's my understanding that the low position is the standard position. The 10 mm high position is the option. At least that's what I was told by the Atlanta tech staff.

    Re: Cool Carrera GT Exhaust System Feature

    hey mike.

    it may sound stupid, but i am considering picking up an extra driver seat in the wide just in case i put on a few lbs some day :-)

    Re: Cool Carrera GT Exhaust System Feature

    Ben,

    I don't think it sounds stupid at all. There's no telling how many or for how long spares will be available.

    I'm actually mulling over buying a spare underbody CFRP panel assembly for when I bottom the car out and grind the crap out of the bottom side. I assume it's only a matter of when, not if

    I'm not even close to knowing what to think about the spares subject.

    Re: Cool Carrera GT Exhaust System Feature

    I think these are good problems to have.

    Re: Cool Carrera GT Exhaust System Feature

    that's a great idea re: the panel. if you check into it, please let me know how many (and which) body parts porsche wants for it.

     
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