Exhaust gas discharge Pressurized air from the turbocharger is supplied to the cylinders. Intake Manifold Intake air is ducted to the turbocharger where it is  compressed. Air Intake This controls the amount  of exhaust through the  turbine. Waste gate  position is actuated by  engine oil pressure. Waste Gas The turbocharger  incorporates a turbine,  which is driven by exhaust  gases and a compressor  that pressurizes the  incoming air. Turbocharger This regulates airflow  to the engine. Throttle Body Exhaust gas is ducted  through the exhaust  manifold and is used to  turn the turbine, which  drives the compressor. Exhaust Manifold Figure 11-9.  Turbocharging system. The waste gate actuator is a spring-loaded piston operated  by engine oil pressure. The actuator, which adjusts the waste  gate position, is connected to the waste gate by a mechanical  linkage. using ground boosting, takeoff manifold pressures may go  as high as 45 "Hg. The control center of the turbocharger system is the pressure  controller. This device simplifies turbocharging to one  control: the throttle. Once the desired manifold pressure is  set, virtually no throttle adjustment is required with changes  in altitude. The controller senses compressor discharge  requirements for various altitudes and controls the oil  pressure to the waste gate actuator, which adjusts the waste  gate accordingly. Thus the turbocharger maintains only the  manifold pressure called for by the throttle setting. Ground Boosting Versus Altitude Turbocharging Operating Characteristics First and foremost, all movements of the power controls on  turbocharged engines should be slow and smooth. Aggressive  and/or abrupt throttle movements increase the possibility of  over-boosting. Carefully monitor engine indications when  making power changes.  11-9 Altitude turbocharging (sometimes called “normalizing”)  is accomplished by using a turbocharger that maintains  maximum allowable sea level manifold pressure (normally  29–30 "Hg) up to a certain altitude. This altitude is specified  by the airplane manufacturer and is referred to as the  airplane’s critical altitude. Above the critical altitude, the  manifold pressure decreases as additional altitude is gained.  Ground boosting, on the other hand, is an application of  turbocharging where more than the standard 29 inches of  manifold pressure is used in flight. In various airplanes  Although a sea level power setting and maximum rpm  can be maintained up to the critical altitude, this does not  mean that the engine is developing sea level power. Engine  power is not determined just by manifold pressure and rpm.  Induction air temperature is also a factor. Turbocharged  induction air is heated by compression. This temperature  rise decreases induction air density, which causes a power  loss. Maintaining the equivalent horsepower output requires  a somewhat higher manifold pressure at a given altitude than  if the induction air were not compressed by turbocharging.  If, on the other hand, the system incorporates an automatic  density controller which, instead of maintaining a constant  manifold pressure, automatically positions the waste gate  so as to maintain constant air density to the engine, a near  constant horsepower output results.