Active aero has long been a controversial topic in the automotive world. Once the hottest new thing in motorsport, it was quickly banned in most top-flite series for safety reasons and to avoid a costly arms race. It then trickled down to the techiest road-going vehicles, and today, just about every hypercar has some kind of wiggly flap or other. You don’t need a seven-figure budget to do active aero, though. If you’re resourceful, you barely need three. That’s all thanks to the shade-tree motorsports set, which has developed some nifty tricks to do active aero on a budget, and it’s all thanks to pop-up headlights.
First, let’s talk about what active aero really is. At its heart, it refers to aerodynamic devices that can be moved to vary their generation of lift or drag. For example, many sports cars have a rear spoiler that extends when driving at speed to generate more downforce. Often, these spoilers can also be tilted up to act as an air brake, creating extra drag to help slow the car down in a braking zone. This is the most common type of active aero on roadgoing vehicles.
In racing, a great example is Formula 1’s Drag Reduction System. It’s the only type of active aero device that’s legal in the series. This sees the vehicles use a movable flap in the rear wing, which, when opened, reduces the downforce generated by the wing while also reducing drag. This allows the cars to hit a higher top speed on the straights. Across the board, these systems are engineered with the help of computational simulations, wind tunnels, and great reams of calculation and analysis.
When it comes to the world of amateur motorsports, everything’s a bit simpler. However, despite its potential complexity, eager tinkerers have explored the prospects for developing active aero at the grassroots level. Keith from parts shop Flyin’ Miata is one such racer. His Targa Miata racecar is a fairly serious build, with a rollcage, sticky tires, and a brilliant Martini livery. Even better, it’s got a huge wing on the back with an active aero system you could build out of junkyard parts.
Keith’s build is a simple setup capable of two positions. In its standard position, the wing is positioned to generate the appropriate amount of downforce to aid with stability and grip. Then, when Keith hits the brakes with the system enabled, the wing is pushed up and forward to act as an airbrake that helps slow the car by generating a great deal of additional drag.
The real magic is in the simplicity of the implementation. Initially, Keith had toyed with using industrial linear actuators to move the wing. These don’t always come cheap, and the parts Keith found couldn’t do the job. Those available to him were either too weak, or too slow. He abandoned plans for a three-position system that could act like a drag reduction system and an air brake. He elected to go back to the drawing board and build one with two modes instead—regular downforce, or tilted forward as an air brake, akin to the operation of the spoilers on many supercars. In the end, the old adage bore fruit–the Miata is always the answer. Keith’s salvation was the actuators from the Miata’s pop-up headlights. They’re plenty strong enough to raise the wing, even at 120 mph, and they’re able to move from one extreme to the other in about half a second or so.
Getting the electronics rigged up was remarkably easy. There’s nothing fancy going on; Keith just hooked up the 12-volt headlight actuators to the brake light circuit. It’s a simple on-off operation. When the brake lights come on, 12 volts goes to the the actuators, which move the wing to the high-drag position to help slow the car. When he comes off the brakes, the wing moves back down. The headlight actuators are only capable of these two extremes, but that’s enough for a barebones active aero system built out of junkyard parts. Keith considered whether this simplistic setup might be a problem, such as if it caused instability in a situation where he was on and off the brakes. Fundamentally though, he notes that when he races the Miata, he’s hard and decisive on the brakes, and it hasn’t proved to be an issue, even when modulating the pedal.
Keith notes that the main benefit of the build is the additional stability under braking. When he built the system, the car had a 350-horsepower V8 under the hood so Keith’s Miata is plenty good at punching through the air, but it puts a great deal of stress on the brakes. The air brake is thus a boon when it comes to slowing the car down from high speed. “It’s like throwing out a drogue chute… you’re pulling on the back of the car, basically… you’re helping keep it stable,” he explains.
It does come with some drawbacks, though. With Keith’s setup, as soon as the wing goes into its air brake position, it becomes virtually impossible to see through the rear window. That can be a problem on track if you’re under attack from behind. He also says he grew tired of people bombarding him with questions in the paddock when he went to the track, along with a deluge of unsolicited suggestions on how to do it better. Sadly, he also had data acquisition problems that prevented him from getting hard data on any actual lap time improvements. However, from a seat-of-the-pants perspective, he credits it with greatly improving his confidence in the car under braking.
Keith isn’t the only one that’s tried this over the years. His tinkering began a decade ago, when he got the idea from Warren van Nus at Exomotive, the company which turns Miatas into Exocet race cars. If you’re a long-time punter around the Chump Car or 24 Hours of Lemons scene, you’ve probably seen others working with similar equipment, too.
It makes almost perfect sense if you’re racing in cost-limited series like these. If your Miata doesn’t need its headlights, you can just move the actuators from the front to the back of the car without taking a hit in the budget. A few bits of wire to hook them up to the brake light circuit, some homebrew hinges and linkages, and you’re golden. Your only main expense would be the wing.
The Miata Turbo forums have a great thread that talks about these kinds of builds. Robert, a Chump Car racer from Texas, noted that he built a similar setup using a single headlight motor that lasted for a full 24-hour race. His team relied on the brake light actuation method, as any kind of more advanced controller would have been against the budget constraints imposed by the series. He credited the setup with greatly improving the car’s stability under braking, particularly in the rain.
It bears noting that you can do this on other cars; it’s not just limited to Miatas. If you don’t have a set of headlight motors kicking around, though, it can be a less enticing prospect. If you can get used ones cheap, dive in; expect new replacements to cost you $150 for one. You might be able to make something work with one, but two gives you double the power and can simplify the build. By the time you’re spending hundreds of dollars, it might be time to consider grabbing some high-powered servos and going for a more advanced design with flexible positioning. With more money, you could consider buying an off-the-shelf active aero wing. These solutions kind of lack the low-buck charm, though.
Ultimately, if you’re looking to experiment with active aero on a budget, it’s hard to go wrong with a setup like this. Chat to your local Miata fanatic if you’re on the hunt for parts. Every city has one, I promise you; you just have to hunt for the yard full of NA shells (shout out to Ray). Grab yourself some bits, do some experiments, and see if you can score yourself a better racecar and some quicker laps to boot. Happy hacking!
Image credits: Flyin’ Miata, YouTube screenshots