3100 HEUI Diesel Truck Engine Air Inlet And Exhaust System

Air Flow Schematic
(1) Air line. (2) Aftercooler core. (3) Inlet manifold. (4) Exhaust outlet from turbocharger. (5) Turbine side of turbocharger. (6) Compressor side of turbocharger.

The components of the air inlet and exhaust system control the quality and the amount of air available for combustion. These components are the air cleaner, turbocharger, aftercooler, cylinder head, valves and valve system components, piston and cylinder, and exhaust manifold.

Inlet air is pulled through the air cleaner, compressed and heated by the compressor wheel in compressor side of turbocharger (6) to about 150°C (300°F), then pushed through the air-to-air aftercooler core (2) and moved to the air inlet manifold (3) at about 43°C (110°F). Cooling of the inlet air increases combustion efficiency, which helps to lower fuel consumption and increase horsepower output. Aftercooler core (2) is a separate cooler core installed in front of the standard engine radiator core of the truck. Ambient temperature air is moved across the aftercooler core by the engine fan and by the ram effect of the vehicles forward motion, this cools the turbocharged inlet air.

From the aftercooler core (2) the air is forced into the cylinder head to fill the inlet ports. Air flow from the inlet port into the cylinder is controlled by the intake valves.

Air Inlet And Exhaust System
(2) Aftercooler core. (4) Exhaust outlet. (5) Turbine side of turbocharger. (6) Compressor side of turbocharger. (7) Exhaust manifold. (8) Exhaust valve. (9) Intake valve. (10) Air inlet.

There are two intake and two exhaust valves for each cylinder. Intake valves open when the piston moves down on the inlet stroke. When the intake valves open, cooled compressed air from the inlet port is pulled into the cylinder. The intake valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. When the piston is near the top of the compression stroke, fuel is injected into the cylinder. The fuel mixes with the air and combustion starts. The force of combustion pushes the piston down on the power stroke. When the piston moves up again, it is on the exhaust stroke. The exhaust valves open, and the exhaust gases are pushed through the exhaust port into the exhaust manifold. After the piston makes the exhaust stroke, the exhaust valves close and the cycle (inlet, compression, power, exhaust) starts again.

Exhaust gases from exhaust manifold (7) enter turbine side of the turbocharger (5) and cause the turbine wheel to turn. The turbine wheel is connected to the shaft which drives the compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet pipe, the muffler and the exhaust stack.

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