C15 and C18 – Series Turbocharger System


Two turbochargers are arranged in a series on some C18 applications.

(A) To the aftercooler

(B) From the actuator on the balance valve

(C) To the Clean Emissions Module

(D) From the air filter

The low-pressure turbocharger compressor wheel pulls the inlet air through the air cleaner and into the air inlet. The air is compressed by the low-pressure turbocharger. Pressurizing the inlet air causes the air to heat up. The pressurized air exits the low-pressure turbocharger through the outlet and the air is forced into the inlet of the high-pressure turbocharger.

The high-pressure turbocharger is used in order to compress the air to a higher pressure. This increase in pressure continues to cause the temperature of the inlet air to increase. As the air is compressed, the air is forced through the outlet of the high-pressure turbocharger and into the air lines to the precooler.

The pressurized inlet air is cooled by the precooler prior to being sent to the aftercooler. The precooler uses engine coolant to cool the air. Without the precooler, the inlet air would be too hot in order to be cooled sufficiently by the aftercooler. The inlet air then enters aftercooler core. The inlet air is cooled further by transferring heat to the ambient air. The combustion efficiency increases as the temperature of the inlet air decreases. Combustion efficiency helps to provide increased fuel efficiency and increased horsepower output.

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