Aerodynamics & Diverting Wind Resistance ?

MPH is a huge factor in aerodynamics. One easy example is the Dodge Daytona. The body was designed to be clean up to road speeds of about 100 MPH. Anything under that speed and the car was clean and relatively stable. From 100 to 150 MPH, the car was a bit twitchy, but a decent sized wicker bill on the spoiler would make the car tolerable.

What happened after 150 should be a textbook lesson in aerodynamics. The body at speeds about 150 MPH started to generate lift. The air pressure under the car was greater than the air pressure over the car and the car would literally try to stand up. It was actually borderline unsafe.

The “cure” was a bigger, more effective rear spoiler with a relatively large wicker bill and a bigger spoiler up front to keep the air from going under the car.

The problem with those modifications is they take a bunch of power. Using a bigger spoiler and wicker bill causes more drag, and more drag takes more power. So that particular car was at a huge disadvantage as a Pro Stock car. In know, for a fact that Alderman hated those cars. You couldn’t win with them unless you wanted to drive a car that was loose over 150 MPH. Pretty easy to go full turtle when the car is unstable at those speeds.

The upshot to all this is this. What looks good at one air speed may not be good at another air speed. To the point the car can become unsafe.

Obviously you are not talking about speeds that high but the principle stands on its own. Unless you have some way to quantify any change you make you have no idea what the end result will be at various MPH.

If you can use CFD that would be a good start. Air flow can be quite counterintuitive. A change that looks good at 100 MPH may be a death trap at 150.