N14 Base Engine Troubleshooting and Repair Manual – 010-999   Air Intake System – Overview

The combustion air system consists of intake air piping, turbocharger, charge air cooler (CAC) piping, CAC, and exhaust piping.

The turbocharger uses exhaust gas energy to turn the turbine wheel. The turbine wheel drives the compressor impeller which provides pressurized air to the engine for combustion. The additional air provided by the turbocharger allows more fuel to be injected to increase the power output from the engine.

NOTE: The correct turbocharger

must
be used. Providing too much additional air will increase the cylinder pressures and shorten the life of the engine.

The turbine and compressor wheels and the shaft are supported by two rotating bearings in the bearing housing. Passages in the bearing housing direct filtered, pressurized engine oil to the shaft bearings and thrust bearings. The oil is used to lubricate and cool the rotating components to provide for smooth operation. The oil then drains from the bearing housing to the engine sump through the oil drain line.

NOTE: An adequate supply of good, filtered oil is very important to the life of the turbocharger.

As the intake air is compressed by the turbocharger, the air is heated. This heated air is then passed through the charge air cooler which cools the air. Cool air is more dense which allows more air to be compressed into the cylinder, yielding a much greater combustion efficiency.