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 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 of an internal combustion engine. The greater massflow through the engine allows an increase in engine power.<ref>{{cite web |url=https://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.{{cn|date=July 2025}} When gas velocity decreases the pressure is increased.{{cn|date=July 2025}} 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, motorcycles. The 1990 Kawasaki Ninja ZX-11 C1 was the first production motorcycle to use one.<ref name=history>{{cite web |url=https://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|archive-date=October 11, 2016|archive-url=https://web.archive.org/web/20161011203610/http://www.sportrider.com/ram-air-test/|url-status=dead}}</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.{{cn|date=July 2025}} 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-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-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>

== References == {{reflist}}

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