The Sauber C9 (later named the Sauber Mercedes C9 or Mercedes-Benz C9) is a Group C prototype racing car introduced in 1987 as a continuation of the partnership between Sauber as a constructor and Mercedes-Benz as an engine builder for the World Sportscar Championship. The C9 replaced the Sauber C8.
Development
The C9 was a development of Sauber's previous C8 design, retaining a monocoque that largely consisted of aluminium, although considerably stiffer and with numerous other improvements. The rear suspension changed from vertically positioned spring/damper units arranged over the top of the gearbox to a horizontal layout aligned with the longitudinal axis of the car. Aerodynamic changes included the repositioning of the combination of oil/water radiator to the nose of the car, which allowed the use of a modified splitter plate. Commensurate with the repositioning of the radiators, the large NACA ducts were removed from the top of the door sills. The rear deck had been considerably re-profiled and the rear wing was now mounted solely on a central support. Aerodynamically, the car had two configurations: one for sprint circuits and a low drag version for the 5.8 kilometre Mulsanne Straight at Le Mans. In its sprint configuration, it produced 4899 lb of downforce at 320 km/h (200 mph) while generating 1225 lb of drag. The sprint circuit configuration had a L/D ratio of 4:1 while the low drag version was around 3:1.[2] The early engines were again prepared by Swiss engine specialist, Heini Mader, though this is now known to have been a cover for Mercedes back door involvement with the project later on.