Chapter 3 Induction and Exhaust  Systems Reciprocating Engine Induction Systems The basic induction system of an aircraft reciprocating engine  consists of an air scoop used to collect the inlet air and ducting  that transfers the air to the inlet filter. The air filter is generally  housed in the carburetor heat box or other housing close by  that is attached to the carburetor or fuel injection controller.  The engine used in light aircraft is usually equipped with  either a carburetor or a fuel-injection system. After air passes  through the fuel metering device, an intake manifold with  long curved pipes or passages is used to send the fuel/air  mixture to the cylinders. An induction air scoop is shown in  Figure 3-1.  The air scoop is located on the engine cowling to  allow maximum airflow into the engine’s induction system.  The air filter, shown in  Figure 3-2,  prevents dirt and other  foreign matter from entering the engine. Filtered air enters  the fuel metering device (carburetor/fuel injector) where the  throttle plate controls the amount of air flowing to the engine.  The air coming out of the throttle is referred to as manifold  pressure. This pressure is measured in inches of mercury  ("Hg) and controls engine power output.