 | |
| Illustration 1 | g00281646 |
Air Inlet And Exhaust System (1) Exhaust manifold (2) Aftercooler (3) Engine cylinder (4) Air inlet (5) Turbocharger compressor wheel (6) Turbocharger turbine wheel (7) Exhaust outlet | |
Clean inlet air from the air cleaners is pulled through air inlet (4) into the turbocharger compressor by turbocharger compressor wheel (5). The rotation of the turbocharger compressor wheel causes the air to compress. The air is forced through a tube to aftercooler (2). The aftercooler lowers the temperature of the compressed air before the air goes into the inlet chambers in each cylinder head. This cooled and compressed air fills the inlet chambers in the cylinder heads. Air flow from the inlet chamber into the cylinder is controlled by the inlet valves.
There are two inlet valves and two exhaust valves for each cylinder. Refer to Systems Operation, "Valve Mechanism". The inlet valves open when the piston moves down on the inlet stroke. The cooled, compressed air is pulled into the cylinder from the inlet chamber.
The inlet valve closes and the piston moves up on the compression stroke. 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 the combustion pushes the piston downward on the power stroke. When the piston moves upward, the piston is on the exhaust stroke. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (1). After the piston makes the exhaust stroke, the exhaust valve closes and the cycle starts again.
Exhaust gases from the exhaust manifold go into the turbine side of the turbocharger. The exhaust gases cause turbocharger turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives turbocharger compressor wheel (5). The exhaust gases exit through exhaust outlet (7) .
Air Inlet And Exhaust System
 | |
| Illustration 2 | g03368222 |
Air Inlet And Exhaust System (1) Muffler (2) From air filters (3) Rear turbocharger (4) Exhaust (5) Front turbocharger (6) SCAC (7) Intake manifold | |
This illustration is a schematic showing the air flow from the air filters to the mufflers on the engine.
The turbochargers are driven by the exhaust (4) from the cylinders which enters the turbine side of the turbochargers (3). The exhaust gas flows through the turbochargers, the exhaust piping, and the mufflers (1) .
The clean air from the air filters (2) enters the compressor side of the turbochargers. The compressed air from the turbochargers flows to the aftercooler. Refer to Illustration 2 shows the SCAC cores on the engine. The aftercooler core is water cooled. The air flows through the aftercooler, the aftercooler cools the air. The air then flows through the intake manifold (7) to the cylinders and combines with the fuel for combustion.
Aftercooler
The aftercooler is located at the center of the vee. The aftercooler has a coolant charged core assembly (assemblies). Coolant from the water pump flows through a pipe into the aftercooler. Coolant then flows through the core assembly (assemblies). Coolant flows back out the aftercooler through a different pipe.
Inlet air from the compressor side of the turbochargers flows into the aftercooler through pipes. The air then passes through the fins of the core assembly (assemblies) which lowers the temperature. The cooler air flows out of the bottom of the aftercooler and into the air chamber. The air flows through the elbows to the inlet ports (passages) in the cylinder heads.
Turbocharger
Four turbochargers are used on the top of the engine. Two turbochargers are located on each side of the vee. The turbine side of each turbocharger is mounted to the respective exhaust manifold. The compressor side of each turbocharger is connected by pipes to the top of the aftercooler housing.
 | |
| Illustration 3 | g00281664 |
Turbocharger (Typical Example) (1) Compressor wheel. (2) Bearing. (3) Oil inlet. (4) Bearing. (5) Turbine wheel. (6) Exhaust outlet. (7) Air inlet. (8) Coolant passages. (9) Oil outlet. (10) Exhaust inlet. | |
The exhaust gases go into the exhaust inlet (10) of the turbine housing. The gases push the blades of turbine wheel (5). The turbine wheel and the compressor wheel turn at speeds up to 90,000 rpm.
Clean air from the air cleaners is pulled through the compressor housing air inlet (7) by the rotation of the compressor wheel (1). The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power because the compression allows the engine to burn additional fuel with greater efficiency.
The maximum speed of the turbocharger is controlled by the engines electronic control of fuel delivery. When the engine is operating, the height above the sea level also controls the maximum speed of the turbocharger.
Bearing (2) and bearing (4) in the turbocharger use engine oil under pressure for lubrication. The oil is sent through the oil inlet line to oil inlet (3) at the top. The oil then goes through passages in the center section for lubrication of the bearings. The oil goes out of oil outlet (9) at the bottom. The oil then goes back to the engine block through the drain line.
The bearing housing in the turbocharger is also cooled by the jacket water coolant. Coolant from the coolant inlet line enters the side of the center section. The coolant travels through the coolant passages (8) in the bearing housing. The coolant then leaves the turbocharger at the other side of the center section. The coolant outlet lines then take the coolant back to the jacket water radiator top tank.
Valve System Components
The valve system components control the flow of the inlet air and the exhaust gases into and out of the cylinders during engine operation.
The crankshaft gear drives the camshaft gears through idlers. Both camshafts must be timed to the crankshaft in order to get the correct relation between the piston and the valve movement.
The camshafts have three lobes for each cylinder. Two lobes operate the valves and one operates the fuel injector.
 | |
| Illustration 4 | g01042301 |
Valve system components (1) Rocker arm (2) Bridge (3) Rotocoil (4) Valve spring (5) Pushrod (6) Lifter | |
As each camshaft turns, the lobes on the camshaft cause lifters (6) to move up and down. The up or down movement causes pushrods (5) to move rocker arms (1). The movement of the rocker arms cause the bridges (2) to move downward. The bridges open two valves simultaneously. The valves can be either inlet valves or exhaust valves. There are two inlet valves and two exhaust valves for each cylinder.
Valve springs (4) cause the valves to close when the lifters move downward.
Rotocoils (3) cause the valves to turn while the engine is running. The rotation of the valves keeps the carbon deposits on the valves to a minimum which gives the valves a longer service life.