Can it be done? Of course–if you’re willing to put more than a minute into it.
A basic course in racecar aerodynamics: what lift is, and how to counteract it with downforce.
Aero expert Steve Stafford sets things straight with aerodynamic basics.
Diffusers can be a great addition to an aero package, but they need to be carefully designed to make more downforce than just their weight.
