ENGINE SYSTEMS 19 Figure 12 Air flow diagram Air flow The rest of the hot exhaust gas expands and flows to the VGT, spins the turbine wheel, and flows from the VGT outlet to the engine exhaust pipe. Air enters and flows through the air filter assembly and mixes with air from crankcase ventilation. The VGT compresses the air mixture before it enters the Charge Air Cooler (CAC). Cooled compressed air flows from the CAC into the air intake manifold that directs air to the intake ports for each cylinder head. The VGT compressor wheel, on the same shaft as the turbine wheel, compresses the mixture of filtered air and air from crankcase ventilation. The VGT responds directly to engine loads.
During heavy load, an increased flow of exhaust gases turns the turbine wheel faster. This increased speed turns the compressor impeller faster and supplies more air or greater boost to the intake manifold. Conversely, when engine load is light, the flow of exhaust gases decreases and less air is pumped into the intake manifold. After combustion, hot exhaust gas is forced through the exhaust manifolds to the EGR cooler and VGT. Some hot exhaust gas is cooled in the EGR cooler and flows through the EGR control valve back through the air intake manifold to mix with filtered air. This reduces nitrogen oxide (NOx) emissions and noise.
EGES295-2 Read all safety instructions in the "Safety Information" section of this manual before doing any procedures. Follow all warnings, cautions, and notes. ©2006 International Truck and Engine Corporation