A hood scoop is a feature built into the hood of a car or truck for functional or decorative purposes. The hood scoop will allow air to pass through the top of the hood and into the engine compartment, thereby providing the engine with cooler air to use during combustion. This can enhance the power output of the engine in some cases. To make this air intake possible, the hood scoop must be raised above the surface of the hood to literally "scoop" the air that passes over the hood into the engine compartment. In other cases, the scoop may be purely ornamental to enhance the aesthetic of the car.
Performance automobiles often feature a hood scoop to ensure any extra bit of power goes to the engine, though the hood scoop is becoming more popular on other vehicles as well. The air intake can enhance power in the engine by allowing cooler, denser air to reach the air intakes. At high speeds, the air can enter the engine compartment more forcefully, again enhancing the power output of the engine in some cases. Sometimes known as ram air, this high speed air delivery is usually only effective on racing vehicles since the car must be traveling at very high speeds for any effect to be felt.
The location of the hood scoop on the hood is crucial toward its effectiveness. It is usually located toward the rear of the hood, closest to the windshield, because the pressure from the wind is likely to be higher here. This forces the air downward into the scoop, which must be strategically positioned inside the engine compartment as well to deliver the cooler air to the parts of the engine that will benefit from it. A significant amount of design must go into positioning and designing the shape of the scoop to ensure the benefits of the hood scoop are felt.
Decorative hood scoops can be placed anywhere on the hood. They produce little extra drag, which means they will not hinder performance very much, if at all. The inside of the hood scoop will be blocked off, meaning the decorative scoop will not deliver any cooler air to the engine. Most decorative scoops do not go through the hood like performance scoops; instead, they are simply a feature of the outside layer of the hood only. They can help to make the vehicle look like more of a performance vehicle, and the popularity of decorative scoops has led to more manufacturers including them on non-performance models.