After reaching the fuel manifold valve, the fuel is distributed  to the individual fuel discharge nozzles. The discharge  nozzles, which are located in each cylinder head, inject the  fuel-air mixture directly into each cylinder intake port.  or boosted, by either a supercharger or a turbosupercharger,  the aircraft’s service ceiling can be increased. With these  systems, an aircraft can fly at higher altitudes with the  advantage of higher true airspeeds and the increased ability  to circumnavigate adverse weather.  A fuel injection system is considered to be less susceptible  to icing than a carburetor system, but impact icing on the air  intake is a possibility in either system. Impact icing occurs  when ice forms on the exterior of the aircraft and blocks  openings, such as the air intake for the injection system.  A supercharger is an engine-driven air pump or compressor  that provides compressed air to the engine to provide  additional pressure to the induction air so that the engine can  produce additional power. It increases manifold pressure and  forces the fuel-air mixture into the cylinders. Higher manifold  pressure increases the density of the fuel-air mixture and  increases the power an engine can produce. With a normally  aspirated engine, it is not possible to have manifold pressure  higher than the existing atmospheric pressure. A supercharger  is capable of boosting manifold pressure above 30 "Hg.  The following are advantages of using fuel injection:  The following are disadvantages of using fuel injection:  For example, at 8,000 feet, a typical engine may be able to  produce 75 percent of the power it could produce at mean  sea level (MSL) because the air is less dense at the higher  altitude. The supercharger compresses the air to a higher  density allowing a supercharged engine to produce the same  manifold pressure at higher altitudes as it could produce  at sea level. Thus, an engine at 8,000 feet MSL could still  produce 25 "Hg of manifold pressure whereas, without a  supercharger, it could only produce 22 "Hg. Superchargers  are especially valuable at high altitudes (such as 18,000 feet)  where the air density is 50 percent that of sea level. The use  of a supercharger in many cases will supply air to the engine  at the same density it did at sea level.  To increase an engine’s horsepower, manufacturers have  developed forced induction systems called supercharger  and turbosupercharger systems. They both compress the  intake air to increase its density. The key difference lies in  the power supply. A supercharger relies on an engine-driven  air pump or compressor, while a turbocharger gets its power  from the exhaust stream that runs through a turbine, which in  turn spins the compressor. Aircraft with these systems have  a manifold pressure gauge, which displays MAP within the  engine’s intake manifold.  On a standard day at sea level with the engine shut  down, the manifold pressure gauge indicates the ambient  absolute air pressure of 29.92 "Hg. Because atmospheric  pressure decreases approximately 1 "Hg per 1,000 feet of  altitude increase, the manifold pressure gauge indicates  approximately 24.92 "Hg at an airport that is 5,000 feet above  sea level with standard day conditions.  As a normally aspirated aircraft climbs, it eventually reaches  an altitude where the MAP is insufficient for a normal climb.  This altitude limit is known as the aircraft’s service ceiling,  and it is directly affected by the engine’s ability to produce  power. If the induction air entering the engine is pressurized,  The components in a supercharged induction system are similar  to those in a normally aspirated system, with the addition of  a supercharger between the fuel metering device and intake  manifold. A supercharger is driven by the engine through a  gear train at one speed, two speeds, or variable speeds. In  addition, superchargers can have one or more stages. Each  stage also provides an increase in pressure and superchargers  may be classified as single stage, two stage, or multistage,  depending on the number of times compression occurs.  An early version of a single-stage, single-speed supercharger  may be referred to as a sea-level supercharger. An engine  equipped with this type of supercharger is called a sea-level  engine. With this type of supercharger, a single gear-driven  impeller is used to increase the power produced by an engine  at all altitudes. The drawback with this type of supercharger is  a decrease in engine power output with an increase in altitude.  Single-stage, single-speed superchargers are found on many  high-powered radial engines and use an air intake that faces  forward so the induction system can take full advantage of  7-12  Superchargers and Turbosuperchargers  Superchargers  • Reduction in evaporative icing  • Better fuel flow  • Faster throttle response  • Precise control of mixture  • Better fuel distribution  • Easier cold weather starts  • Difficulty in starting a hot engine  • Vapor locks during ground operations on hot days  • Problems associated with restarting an engine that  quits because of fuel starvation 