This illustration shows a simple aftercooled single turbo system. Let's follow the intake airflow to see how it works. (Courtesy Honeywell Turbo Technologies) A. After the intake air passes through the air filter it is routed to the turbocharger's compressor inlet (1). B. The air is then compressed, which increases its density—or amount of mass per unit of volume—by the turbo's compressor section, and is discharged through a boost tube (2). C. Most of today's turbo systems use an aftercooler, also known as an intercooler or charge-air cooler, to receive the hot, boosted air as it leaves the compressor. The cooler removes the excess heat, which allows for further air density improvements while also cooling the intake air charge (3). D. Another boost tube then routes the air from the cooler's discharge side to the engine's intake manifold where the air is routed to the intake valves and it enters each cylinder (4). E. An increased fuel injection charge, based upon the now more dense air charge, is introduced and combustion occurs. After combustion, the exhaust passes through the exhaust valve and into the exhaust manifold (5). F. The exhaust manifold routes the exhaust gas energy in the form of heat and pressure into the turbine stage of the turbocharger (6). G. The turbine housing causes backpressure. This backpressure and heat expand against the turbine wheel blades causing the turbine wheel and shaft to spin, which in turn drives the compressor wheel on the intake side of the system. The remaining exhaust then leaves the turbine stage and enters the exhaust system (7).
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