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
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
