Hood Scoop - Scoop Design

Scoop Design

To be effective, a functional scoop must be located at a high-pressure area on the hood. For that reason, some functional scoops are located at the rear of the hood, near the vehicle's cowl, where the curvature of the windshield creates such a high-pressure zone, and may be placed so that their opening faces the windshield (a reversed scoop).

The scoop will be most effective if it is either mounted high enough to clear the boundary layer (the slow-moving air that clings to the surface of a moving object) or if it is a "NACA duct," mounted below the surface and designed to draw the faster moving air outside of the boundary layer into the duct. A shallow scoop that is not a NACA duct may not admit a useful amount of air even if it is open.

Under the hood, an effective scoop must funnel air into the engine's intake in as short and direct a path as possible, preferably through a tube or channel that is insulated against underhood heat.

A scoop may be part of the hood, or may be part of the engine's air cleaner assembly, protruding through a hole cut into the bonnet. Such a scoop is called a shaker hood, because the scoop vibrates noticeably when the engine is running, especially under power.