View source for Ram-air intake

{{Short description|Vehicle air intake design}}
{{More citations needed|date=June 2018}}
[[File:1964 thunderbolt engine air intakes.jpg|thumb|300px|Factory dual ram-air intakes on a [[Ford Fairlane Thunderbolt|Ford Thunderbolt]]]]

A '''ram-air intake''' is an [[intake]] design which uses the dynamic air [[pressure]] created by vehicle motion, or [[ram pressure]], to increase the static air pressure inside of the intake manifold on an [[internal combustion engine]], thus allowing a greater massflow through the engine and thereby increasing engine power.<ref>{{cite web |url=http://www.motociclismo.es/noticias/industria/articulo/el-ram-air |title=Sistema aerodinámico Ram-Air: funcionamiento |last1=Cabello |first1=Cabello |last2=Baz |first2=Pablo |work=Motociclismo |date=2015-06-13 |language=es |trans-title=Aerodynamic system ram-air: operating mode |access-date=2016-08-20}}</ref>

==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]]s. The 1990 [[Kawasaki Ninja  ZX-11]] C1 model used a ram-air intake, the very first on any production motorcycle.<ref name=history>{{cite web |url=http://www.cycleworld.com/2013/12/24/30-year-history-of-kawasaki-ninja-motorcycles-1984-gpz900-to-1990-zx-11-part-one//|last=Burns |first=John |title=30 Years of Ninjas: 1984 GPz900 Ninja to 1990 ZX-11!| publisher=[[Cycle World]]|access-date=December 2, 2016|date=December 24, 2013 }}</ref><ref name=ramairtest>{{cite web |url=http://www.sportrider.com/ram-air-test//|title=Ram Air: Test|publisher=Sport Rider|access-date=December 2, 2016|date=October 1999}}</ref> 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]] of an engine, {{citation needed span|text=they can be difficult to combine with carburetors, which rely on a [[venturi effect|venturi]]-engineered pressure drop to draw fuel through the main jet.  As the pressurised ram-air may kill this venturi effect, the carburetor needs to be designed to take this into account.|reason=OR without a reliable citation.|date=April 2025}} 

At low speeds (subsonic speeds) increases in static pressure are however limited to a few percent.{{clarification needed|reason=Meaning what (in real-world terms, for general online encyclopedia users)?|date=April 2025}}{{cn|date=April 2025}}

<gallery mode=packed heights=150px>
File:1969 Ford Mustang Mach I.jpg|[[Shaker scoop|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]]
</gallery>

==See also==
*[[Air filter]]
*[[Booster pump|Booster]]
*[[Ramjet]]
*[[Supercharger]]
*[[Turbocharger]]
*[[Diffuser (automotive)]]

== References ==
{{reflist}}

{{Automotive engine |collapsed}}

[[Category:Engine technology]]
[[Category:Automotive technologies]]
[[Category:Motorcycle engines]]