Shift-time Limited Acceleration: Final Drive Ratios in Formula SAE 2004-01-3554
Even with relatively unrestrictive rules in the Formula SAE competition, established teams are fighting diminishing returns in vehicle mass and engine horsepower. The typical FSAE vehicle incorporates a six speed gearbox, yet reaches a (course-limited) top speed in competition of only about 110 kph. Selecting a final drive for this top speed would result in 5 gearshifts in less than 4 seconds. As a result, final drive ratio is very sensitive to shift delay time. Although vehicle mass, engine performance and traction still play a major role, a typical FSAE vehicle acceleration is significantly limited by the time it takes to complete a gearshift.