What Does a Spoiler Do for Aerodynamics?

November 8, 2013

Spoilers are more than industrial design flourishes like tailfins; they're aerodynamic lifts. Learn about spoiler types, installation and functioning.

Automobile Spoiler

There are several spoiler types that can change the aerodynamics of a car. To get a better understanding of the purpose of a spoiler, look at what exactly changes in the aerodynamics car depending on the type.

Chin Spoilers
Chin spoilers are installed on the bottom of the car's edges, creating a skirt around the car. The principle behind this is that the spoiler alters the air flow that goes under the car. Having a lot of air flow under a car is not desirable. This is why these skirts can be quite important for the performance of a car. Too much air flow under the car can cause turbulence, leading to problems with the drive shaft, gearbox and an increase the drag of the car.

This type of spoiler then encourages air flow to pass the car on each side instead of going underneath the vehicle. The lower the chin spoilers are the less air that will get underneath your car. This is why you see race cars with their chin spoilers nearly touching the ground.

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Wings help add downforce to the back of the car so the tires catch traction. Sometimes the most obnoxious looking wings are the best for aerodynamics, but usually just a small spoiler is needed for an everyday car. Wings are mainly for cars with very high horsepower that can't get their tires to the ground well. The rear spoiler or wing spoiler adds what is called an air foil to the rear of the car. With a rear spoiler, the lift of a car can be drastically lowered, making the rear end of the car a lot easier to handle.

Fastback Spoilers
The reason cars that have a fastback use a spoiler is the spoiler reduces the slope of the fastback. A spoiler that decreases the slope by 20 percent reduces the drag of the car drastically because the air flow over the car will follow the roof of the car far more smoothly.

Understanding Drag
The drag of a car is how hard the car has to fight to push through the air when traveling at certain speeds. For example, a car driving at 120 mph has to fight with four times the drag as opposed to a car driving at 60 mph. The more the car needs to work against the drag, the harder it is on the car at higher speeds.

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Understanding Lift
Another thing that a spoiler can help a car with is the lift. If a car is traveling at a high speed and the lift of the car is far too much, the car itself can become quite unstable. A high speeds, as air rushes under the car it can actually lift it from the road. The lift of a car is far more unstable at the back, reducing traction. When not kept in check, the lift at higher speeds can make the car slip quite easily.

How to Install Spoilers

Ensuring you have the correct tools and following the necessary steps to complete the project, you will find that it is not as difficult to install spoilers as it would initially appear.

Check the Specifications
Start by making a note of all the specifications of the car so that you can be sure that the spoiler you obtain is the right one. The make and model of the vehicle is necessary because you will need to obtain a part that is made for the vehicle. Take careful length and width measurements to compare them to the part you want to buy, which will ensure that you get the right fit. List what tools and fittings will be required to complete the installation. Whether it is a racing wing or a rear diffuser, there are several types of spoilers to choose from, so it's worth doing some research if help is needed to make a decision.

Assemble the Parts
Once you make the purchase, you have to complete some assembly work. The brackets that hold the spoiler to the car need to be put together in preparation for the installation. Follow the instructions for this process, making sure that you have the correct tools for the job. Make sure that the brackets are securely bolted in place. At this stage, it is also worthwhile dry-fitting the spoiler to ensure that you get it the correct way around. Use a marker to outline the points where holes need to be drilled for the fasteners.

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Drill the Bolt Holes
Drill the points on car body where the fasteners will be fitted. A power drill will be necessary for this purpose. Attach a drill bit that is suitable for use with metal and of a correct diameter to suit the bolts that are being used. If in doubt, use a drill bit that is smaller than the bolts; the size of the holes can always be increased, but not reduced. When drilling, apply sufficient pressure to pass through completely, no matter how many layers of metal. Use a soft cloth or a vacuum to clean away the resulting particles. Use a sander to tidy any jagged inner edges of the holes, and prevent rust by applying paint or sealant.

Install the Spoiler
Once the holes are drilled, lift the spoiler into place, which is likely to be easier with a friend's help. Hold it in position while you slot the fasteners into the holes. Ensure that washers are positioned on the underside of the body. Firmly secure the nuts with a wrench and check that the spoiler is tightly attached.