Ram-air intake: Difference between revisions

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A ram-air intake is any 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 hence increasing engine power.^[1]

Design features

The ram-air intake works by reducing the intake air velocity by increasing the cross-sectional area of the intake ducting. When gas velocity goes 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 motorcycles and performance cars. The 1990 Kawasaki Ninja ZX-11 C1 model used a ram-air intake, the very first on any production motorcycle.^[2]^[3] 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, 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, or, alternatively, the engine may need fuel-injection.

At low speeds (subsonic speeds) increases in static pressure are however limited to a few percent.

Aircraft

Pitot sensors are used to measure ram pressure which, along with static pressure, is used to estimate the airspeed of an aircraft.

TA-4SU Super Skyhawk, note the ram-air intake mounted on the portside air intake for cooling the jet engine.
Mikoyan-Gurevich MiG-15
Diagram of piston engine with (from left to right):
1. ram-air intake,
2. air filter,
3. mass flow sensor,
4. butterfly valve,
5. air box,
6. intake runners,
7. intake valve,
8. piston,
9. exhaust valve,
10. extractor pipe,
11. collector,
12. catalytic converter,
13. muffler.

References

^ Cabello, Cabello; Baz, Pablo (2015-06-13). "Sistema aerodinámico Ram-Air: funcionamiento" [Aerodynamic system ram-air: operating mode]. Motociclismo (in Spanish). Retrieved 2016-08-20.
^ Burns, John (December 24, 2013). "30 Years of Ninjas: 1984 GPz900 Ninja to 1990 ZX-11!". Cycle World. Retrieved December 2, 2016.
^ "Ram Air: Test". Sport Rider. October 1999. Retrieved December 2, 2016.

[1] Cabello, Cabello; Baz, Pablo (2015-06-13). "Sistema aerodinámico Ram-Air: funcionamiento" [Aerodynamic system ram-air: operating mode]. Motociclismo (in Spanish). Retrieved 2016-08-20.

[history-2] Burns, John (December 24, 2013). "30 Years of Ninjas: 1984 GPz900 Ninja to 1990 ZX-11!". Cycle World. Retrieved December 2, 2016.

[ramairtest-3] "Ram Air: Test". Sport Rider. October 1999. Retrieved December 2, 2016.

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+{{Short description|An intake design which uses air pressure from vehicle motion to increase static air pressure}}
-{{unreferenced|date=May 2009}}
+{{More citations needed|date=June 2018}}[[File:Kawasaki ZX-12R 071118 front.jpg|thumb|Ram-air intake on a [[Kawasaki ZX-12R]]]]
-{{TOCright}}
-A '''ram-air intake''' is any [[intake]] design which uses the dynamic air [[pressure]] created by vehicle motion to increase the static air pressure inside of the intake manifold on an engine, thus allowing a greater massflow through the engine and hence increasing engine power.
+A '''ram-air intake''' is any [[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 hence 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>
 ==Design features==
-[[File:2010 Porsche 911 GT3 RS - Flickr - The Car Spy (12).jpg|thumb|left|Ram-air intake of a [[Porsche 911 GT3|Porsche  GT3 RS]]]]
+[[File:Ram air on Mustang Mach 1.JPG|right|thumb|Ram air intakes on a 1973 [[Mustang Mach 1]]]]
-[[Image:Harley motorcycle with ram air and cold air gooseneck mounted hypercharger intake.jpg|thumbnail|right|Motorcycle with gooseneck mounted hypercharger air intake]]
+[[File:Harley motorcycle with ram air and cold air gooseneck mounted hypercharger intake.jpg|thumb|right|Motorcycle with gooseneck mounted hypercharger air intake]]
-The ram air intake works by reducing the intake air velocity by increasing the cross sectional area of the intake ducting. When gas velocity goes down the dynamic pressure is reduced while the static pressure is increased. The increased static pressure in the plenum chamber has a positive effect on engine power, both because of the pressure itself and the increased air density this higher pressure gives.
+The ram-air intake works by reducing the intake air velocity by increasing the cross-sectional area of the intake ducting. When gas velocity goes 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 [[motorcycle]]s and performance cars. Ram-air was a feature on some cars in the sixties, falling out of favor in the seventies, but recently making a comeback.  While ram-air may increase the [[volumetric efficiency]] of an engine, they can be difficult to combine with carburetors, which rely on a [[venturi effect|venturi]]-engendered pressure  drop to draw fuel through the main jet.  As the pressurised ram-air may kill this venturi effect, the carburetor will need to be designed to take this into account; or the engine may need [[fuel-injection]].
+Ram-air systems are used on high-performance vehicles, most often on [[motorcycle]]s and performance cars. 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, 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, or, alternatively, the engine may need [[fuel-injection]].
+At low speeds (subsonic speeds) increases in static pressure are however limited to a few percent.
-Modern parachutes and kites use a ram-air system to pressurise a series of cells to provide the aerofoil shape.
-At low speeds (subsonic speeds) increases in static pressure are however limited to a few percent. Given that the air velocity is reduced to zero without losses the pressure increase can be calculated accordingly. The lack of losses also means without heating the air. Thus a ram-air intake also is a [[cold air intake]]. In some cars the intake is placed behind the radiator, where not only the air is hot, but the pressure is ''below'' ambient pressure. The ram-air intake effect may be small, but so are other mild tuning techniques to increase cylinder filling like using larger, fresh [[air filter]]s, high flow [[mass flow sensor]]s, velocity stacks, tuned air box and large tubes from the filter to the engine.
 ==Aircraft==
-[[Pitot tube|Pitot]] sensors are used to measure ram pressure, which is added to static pressure to derive the [[airspeed]] of an aircraft.
+[[Pitot tube|Pitot]] sensors are used to measure ram pressure which, along with static pressure, is used to estimate the [[airspeed]] of an aircraft.
 <gallery>
-File:TA-4SU Skyhawk cockpits.jpg|T[[A-4SU Super Skyhawk]], note the Ram-air intake mounted on the portside air intake for cooling the jet engine.
+File:TA-4SU Skyhawk cockpits.jpg|[[TA-4SU Super Skyhawk]], note the ram-air intake mounted on the portside air intake for cooling the jet engine.
 Image:MiG-15 RB2.jpg|Mikoyan-Gurevich MiG-15
-Image:Piston engine breathing.svg|Diagram of piston engine with (from left to right): 1.) Ram-air intake, 2.) [[Air filter]], 3.) [[mass flow sensor]], 4.) [[butterfly valve]], 5.) [[air box]], 6.) [[Cylinder head porting|intake runners]], 7.) [[intake valve]], 8.) [[piston]], 9.) [[Cylinder head porting|exhaust valve]], 10.) [[Exhaust manifold|extractor pipe]], 11.) [[Exhaust manifold|collector]], 12.) [[catalytic converter]], 13.) [[muffler]].
+Image:Piston engine breathing.svg|Diagram of piston engine with (from left to right): {{ordered list | ram-air intake, | [[air filter]], | [[mass flow sensor]], | [[butterfly valve]], | [[air box]], | [[Cylinder head porting|intake runners]], | [[intake valve]], | [[piston]], | [[Cylinder head porting|exhaust valve]], | [[exhaust manifold|extractor pipe]], | [[exhaust manifold|collector]], | [[catalytic converter]], | [[muffler]].}}
 </gallery>
 ==See also==
 *[[Air filter]]
-*[[Booster]]
+*[[Booster pump|Booster]]
 *[[Ramjet]]
 *[[Supercharger]]
 *[[Turbocharger]]
-*[[Cold air intake]]
-*[[Warm air intake]]
-*[[Short ram air intake]]
 *[[Diffuser (automotive)]]
 == References ==
 {{reflist}}
 {{Automotive engine |collapsed}}
 [[Category:Engine technology]]
-[[Category:Vehicle modification]]
 [[Category:Automotive technologies]]
 [[Category:Motorcycle engines]]

v t e Internal combustion engine
Part of the Automobile series
Engine block and rotating assembly	Balance shaft Block heater Bore Connecting rod Crankcase Crankcase ventilation system (PCV valve) Crankpin Crankshaft Core plug (freeze plug) Cylinder (bank, layout) Displacement Flywheel Firing order Stroke Main bearing Piston Piston ring Starter ring gear
Valvetrain and Cylinder head	Flathead layout Overhead camshaft layout Overhead valve (pushrod) layout Tappet / lifter Camshaft Chest Combustion chamber Compression ratio Head gasket Rocker arm Timing belt Valve
Forced induction	Blowoff valve Boost controller Intercooler Supercharger Turbocharger
Fuel system	Diesel engine Petrol engine Carburetor Fuel filter Fuel injection Fuel pump Fuel tank
Ignition	Magneto Compression ignition Coil-on-plug Distributor Glow plug Ignition coil Spark plug Spark plug wires
Engine management	Engine control unit (ECU)
Electrical system	Alternator Battery Dynamo Starter motor
Intake system	Airbox Air filter Idle air control actuator Inlet manifold MAP sensor MAF sensor Throttle Throttle position sensor
Exhaust system	Catalytic converter Diesel particulate filter EGT sensor Exhaust manifold Muffler Oxygen sensor
Cooling system	Air cooling Water cooling Electric fan Radiator Thermostat Viscous fan (fan clutch)
Lubrication	Oil Oil filter Oil pump Sump (Wet sump, Dry sump)
Other	Knocking / pinging Power band Redline Stratified charge Top dead centre
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