Amateur Aerodynamics

After my last round of testing , I made a permanent version of the air dam extensions I tested: This brings my truck’s aerodynamic drag down to around 84-85% of what it was before I started this project:   Modification Percent Change mirrors removed, grill blocked -4.0% 9” air dam -8.6% air dam extensions -3.8% Total -16.4%   I didn’t expect to get that much with these changes, especially because I haven’t even tested anything on or around the bed, rear undercarriage, tailgate, rear wheel housings, or rear bumper.   Tailgate   Many websites claim that lowering a truck’s tailgate increases its drag. This was even explored on an episode of the popular television show Mythbusters ; the show’s hosts put a model truck in a water tunnel to illustrate the recirculation that happens in the bed (and ran some fuel economy tests with the tailgate down, removed,...

Over the past several months, I’ve tested eight different spoilers on my car. I could test more, but I’ve reached a point where I would rather install something permanently and move on to other things, leaving this spoiler project behind. Hence this Spoiler Roundup. Let's meet the competitors: Straight Gurney flap Sinusoidal Gurney flap Commercial lip strip 10 ° board 20 ° board 20 ° board with slot 30 ° board Hellcat. I want this one to win only because I enjoy saying "Hellcat." Which one should I use, if any? That depends on a few things, including my goals , my design limitations, and how much I want to permanently alter the car.   Goals: I want to reduce lift and improve stability as much as possible without increasing drag or, if possible, even decreasing drag.   Limitations: I don’t want to extend the factory spoiler backward at all. Upward is fine, but I use a hatchback tent when I roadtrip that won’t fit if I elongate the spoiler.   Alterations: I don’t care...