Rear Diffusers

When constructing a race car, no matter whether it’s a purpose built track machine or a modified production vehicle, car builders try to achieve an aerodynamic balance between drag and downforce. Minimizing drag reduces the air resistance encountered by the car, allowing it to go faster. Downforce is necessary so the tires stay firmly planted on the track surface for optimal power delivery, steering and braking. Diffusers, air dams and side skirts combine to increase down force on race cars. If you want to make your machine look like it’s ready for the track, check out our selection of diffusers.

Although some body mods increase drag to create downforce, this tradeoff is necessary for overall vehicle performance. However, there are component choices a builder can make that maximize downforce without creating excessive drag. Such is the case with a rear diffuser. When combined with an air dam and side skirts, a rear diffuser functions to increase the velocity of the air flowing underneath the car and increase downforce and traction at the tires.

According to Bernoulli’s Principle, when the velocity of air increases, its pressure decreases. This means that the air pressure above the car is greater, and this greater pressure exerted downward provides the necessary downforce. Although components like rear wings can also be used to provide downforce, they create much more aerodynamic drag while doing so than a rear diffuser. The diffuser provides the space for the high velocity, low pressure air flow to decelerate and expand at the rear of the vehicle, creating a pressure differential and more downforce. Diffusers also typically have dividers that allow the air flow to transition to the airstream at the back of the car without creating turbulence and drag.

Of course, the above description applies mainly to a car constructed expressly for racing. Such cars usually have smoother undercarriages to facilitate the increased air flow velocity, and they are driven at much higher speeds than are allowable on the highway, so the average street driven car will not realize all of a diffuser’s benefits. But we know that the visual appeal of a custom rear diffuser and aerodynamic body components in general is just as, if not more important to street driven car owners than functionality, which is why we have the extensive selection of diffusers you see on the page before you.

We offer rear diffusers for most popular cars in materials including carbon fiber, aluminum, urethane, fiberglass, fiberglass composite, ABS plastic and stainless steel. Depending on application, some are designed to be a fully custom addition, while others are replacements for the OE diffuser but are manufactured in an upgraded material like carbon fiber. Some applications are designed to be used with specific exhaust systems. And because each of our rear diffusers is carefully designed for a specific model, regardless of your choice you can count on ease of fitment, and an appearance that will command attention and perfectly complement your vehicle’s styling.