Air Inlet and Exhaust System
SMCS Code: 1050
Air inlet and exhaust system (typical example)
(1) Exhaust manifold
(2) Inlet manifold
(3) Engine cylinders
(4) Air inlet
(5) Turbocharger compressor wheel
(6) Turbocharger turbine wheel
(7) Exhaust outlet
Engines which are naturally aspirated pull outside air through
an air cleaner directly into the inlet manifold (2). The air flows
from the inlet manifold to the engine cylinders (3). The fuel is
mixed with the air in the engine cylinders. After the fuel
combustion occurs in the engine cylinder, the exhaust gases
flow directly to the outside air through the exhaust manifold (1).
Turbocharged engines pull outside air through an air cleaner
into the air inlet (4) of the turbocharger. The suction is caused
by the turbocharger compressor wheel (5). Then, the
turbocharger compressor wheel compresses the air. The air
flows through the inlet manifold (2) which directs an even
distribution of the air to each engine cylinder (3). Air is pulled
into the engine cylinder (3) during the intake stroke of the
piston. Then, the air is mixed with fuel from the fuel injection
Each piston makes four strokes:
The sequence of the strokes by all of pistons in all of the
engine cylinders provides constant air flow to the inlet system
during the engine operation.
The exhaust stroke and the timing of the valve mechanism
pushes combustion gases out of the open exhaust valve
through the exhaust manifold (1). The exhaust gases flow
through the blades of the turbocharger turbine wheel (6) which
causes the turbine wheel and the compressor wheel to turn.
Then, the exhaust gases flow through the exhaust outlet (7) of
the turbocharger to the outside.
The air inlet system is also equipped with a crankcase
ventilation system. The intake strokes of the pistons pull in
atmospheric air to the crankcase.
A turbocharger increases the temperature and the density of
the air that is sent to the engine cylinder. This condition
causes a lower temperature of ignition to develop earlier in the
compression stroke. The compression stroke is also timed in a
more accurate way with the fuel injection. Surplus air lowers
the temperature of combustion. This surplus air also provides
A turbocharger improves the following aspects of engine
Power output is increased.
Fuel efficiency is increased.
Engine torque is increased.
Durability of the engine is increased.
Emissions of the engine are increased.