Amateur Aerodynamics

Setting out to modify your car’s aerodynamics can be daunting. Where should you start? What should you do first? What changes will give you the most bang for your buck?   Unfortunately, you’ll find a variety of answers to these on the internet—many of which will consider themselves the definitive, correct response, and most of which aren’t based on actual data or first-hand experience. Ignore them.   Identify Goals   The first thing you should do is identify your goals . If you don’t have something in mind you want to accomplish, you can’t plan out a way to get there. And the more specific you can be about where you want to end up, the better ability you will have to make effective modifications that accomplish your goals. Take some time first to identify these. Then, make a testing plan: what changes you want to test, how you will test them, and what you will do if the tests are successful or not. This plan can change as you go along (my plans change every few weeks or so

Updated August 10, 2023 Splitters are a popular modification for racers; stop by a forum like Grassroots Motorsports and you’ll find thread after thread on adding a splitter to an existing car. Road cars? Not so much, and I suspect most people who screw an eBay lip to the front of their cars do so for looks. But I wonder, could a splitter on a road car do anything beneficial, in terms of improved stability or reduced drag, or…something else? Should I fit one to my car? Let’s find out. Initial Testing   I mocked up a splitter last year out of corrugated plastic. This isn’t the best choice of material—ideally, you’ll want something stiffer and able to be bolted to the car—but I tried to design it in such a way that I could still get useful information from it. I folded the coroplast over itself, so it’s fairly stiff, and I wrapped it over the existing (short) splitter so that, when taped down on the top and bottom, it doesn’t flex much and any force the splitter develops should be transf