Engine Undertray

Author: Bill Gregory [sansho@rennlist.com]

Date: August 1, 2002

Bruce Anderson recommends removing the tray to provide better cooling to the engine. The tray was also removed from the Porsche Cup racing cars. However, the tray was intended to serve an aerodynamic purpose to help smooth airflow along the bottom of the chassis, as well as provide a directed venting of  engine cooling air, in such a way to minimizing adding to lift at speed. On the balance, most owners seem to remove the bottom panel, with the thought that helping to keep the engine cooler offsets reducing lift at 150 mph. Also, some owners remove the engine undertray during the Spring/Summer, only to replace it during the Winter, to help keep the engine cleaner.
Jon Kaminsky adds: The official Porsche "Silver" sales brochure notes that "time after time, the Weissach designers returned to their wind tunnel to help shape and fine-tune the new-generation 911 Series. When they were done, these '85% new' 911s had many distinctive air management features...a vastly smoother underside- even including the engine and exhaust system...a vastly reduced Cd factor."