A ram-air intake is an

intake An intake (also inlet) is an opening, structure or system through which a fluid is admitted to a space or machine as a consequence of a pressure differential between the outside and the inside. The pressure difference may be generated on the ins ...

design which uses the dynamic air

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and eve ...

created by vehicle motion, or

ram pressure Ram pressure is a pressure exerted on a body moving through a fluid medium, caused by relative bulk motion of the fluid rather than random thermal motion. It causes a drag (physics), drag force to be exerted on the body. Ram pressure is given in ...

, to increase the static air pressure inside of the intake manifold on an

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

, thus allowing a greater massflow through the engine and thereby increasing engine power.

Application

The ram-air intake works by reducing the intake air velocity by increasing the cross-sectional area of the intake ducting. When gas velocity decreases the pressure is increased. The increased pressure in the air box will ultimately have a positive effect on engine output as more oxygen will enter the cylinder during each engine cycle. Ram-air systems are used on high-performance vehicles, most often on performance cars, and, extremely rarely,

motorcycle A motorcycle (motorbike, bike; uni (if one-wheeled); trike (if three-wheeled); quad (if four-wheeled)) is a lightweight private 1-to-2 passenger personal motor vehicle Steering, steered by a Motorcycle handlebar, handlebar from a saddle-style ...

s. The 1990

Kawasaki Ninja ZX-11 The ZZ-R1100 or ZX-11 is a sport bike in Kawasaki's Ninja series made from 1989 to 2001, as the successor to the 1988–1990 Tomcat ZX-10. With a top speed of , it was the fastest production motorcycle from its introduction until 1996, surpass ...

C1 model used a ram-air intake, the very first on any production motorcycle. Ram-air was a feature on some cars in the sixties. It fell out of favor in the seventies, but recently made a comeback. While ram-air intakes may increase the

volumetric efficiency Volumetric efficiency (VE) in internal combustion engine engineering is defined as the ratio of the equivalent volume of the fresh air drawn into the cylinder during the intake stroke (if the gases were at the reference condition for density) to th ...

of an engine, At low speeds (subsonic speeds) increases in static pressure are however limited to a few percent. File:1969 Ford Mustang Mach I.jpg, Shaker-style ram-air hood scoop on a 1969 Mustang Mach 1 File:ZX12R-2001.jpg, Ram-air intake below the headlight of a

Kawasaki ZX-12R The Kawasaki Ninja ZX-12R is a motorcycle in the Kawasaki Ninja, Ninja sport bike series made by Kawasaki Heavy Industries Motorcycle & Engine, Kawasaki from 2000 through 2006. The inline-four engine produced at low speed, and increased to at h ...

References

{{Automotive engine , collapsed Engine technology Automotive technologies Motorcycle engines

Application

See also

References