Ram-air intake
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A ram-air intake is any air system in the intake which uses the air pressure created by vehicle motion to increase the air pressure inside of the intake manifold on an engine, thus allowing a greater volume of intake air, and hence engine power. A ram-air intake will also provide cooler air, as outside air rather than hot air from the engine compartment is used. For example, a ramjet eliminates many moving parts by using the forward motion to compress incoming air. Technically, there are two types of Ram-Air:
- Systems compress air and force it into the throttle body, and thus the combustion chambers
- Positive pressure systems, which increase pressure only in the airbox and improve intake efficiency
Ram-air systems are used on high performance vehicles, most often on motorcycles and race cars. Ram-air has been a feature on some cars since the late sixties, but fell out of favor in the seventies, and has only recently made a comeback. Modern parachutes use a ram-air system to pressurise a series of cells to provide the aerofoil shape.
However, Fluid Dynamics can support claims that only 3 % higher volume of intake air is accomplished at speeds attainable by high performance and race cars (and an intake on the side reduce the volume by 3 %). Forcing a large volume of air into a cone by motion alone is only possible at supersonic speeds (below that it reduces the volume)
