- air cleaner
- turbocharger
- aftercooler (if equipped)
- inlet manifold (passages inside the cylinder block)
- cylinder head
- valves
- valve system components
- exhaust manifold
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| Illustration 1 | g00327243 |
Air inlet and exhaust system | |
Clean inlet air from the air cleaner is pulled through air inlet (6) of the turbocharger by the turning of compressor wheel (4). The compressor wheel causes a compression of the air. The air then flows to the aftercooler (if equipped), and then to inlet manifold (2) of the engine. When the inlet valves open, the air flows into engine cylinders (3). The air is mixed with the fuel for combustion. When the exhaust valves open, the exhaust gases go out of the engine cylinders and into exhaust manifold (1). From the exhaust manifold, the exhaust gases flow through the blades of turbine wheel (5). This causes the turbine wheel and compressor wheel to turn. The exhaust gases then flow out of exhaust outlet (7) of the turbocharger.
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| Illustration 2 | g00332861 |
Air inlet and exhaust system (1) Exhaust manifold (2) Inlet manifold and aftercooler (4) Air inlet (7) Exhaust outlet (8) Turbocharger (9) Cylinder head | |
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| Illustration 3 | g00332864 |
Airflow schematic (typical example) (1) Exhaust manifold (2) Inlet manifold and aftercooler (4) Air inlet (7) Exhaust outlet (8) Turbochargers | |
Aftercooler
Some engines have an aftercooler (2). The aftercooler is installed above the inlet manifold.
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| Illustration 4 | g00542273 |
Air inlet system (typical example) (1) Turbocharger (2) Aftercooler (3) Elbow on the front bonnet of the oil cooler | |
The aftercooler has a core assembly that is charged by coolant. Coolant from elbow (3) on the front bonnet of the oil cooler flows through the aftercooler core assembly. The coolant then flows out of the aftercooler through a different pipe into the rear of the cylinder block.
The inlet air from the compressor side of the turbocharger flows into the aftercooler. The air passes through the core assembly which lowers the temperature as much as 38°C to 93°C (100°F to 200°F). The cooler air flows out of the bottom of the aftercooler and into the air chamber. The cooler air then flows through the inlet ports (passages) in the cylinder heads. Cooler air is denser air. Dense air will help the engine burn the fuel more efficiently. This gives the engine more power.
Turbocharger
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| Illustration 5 | g00542300 |
Twin turbochargers (1) Exhaust manifolds (2) Oil drain line (one on each side) (3) Oil supply line (one on each side) (4) Air inlet (7) Exhaust outlet (20) Air outlet | |
Two turbochargers are mounted on the rear of the engine. All of the exhaust gases from the left exhaust manifold goes through the left turbocharger, and the right turbocharger uses the exhaust from the right exhaust manifold.
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| Illustration 6 | g00332960 |
Turbocharger (typical example) (4) Air inlet (5) Compressor wheel (6) Turbine wheel (7) Exhaust outlet (8) Compressor housing (9) Thrust bearing (10) Sleeve (11) Lubrication inlet port (12) Turbine housing (13) Sleeve (14) Sleeve (15) Oil deflector (16) Bearing (17) Oil outlet port (18) Bearing (19) Exhaust inlet (20) Air outlet | |
The exhaust gases go into the turbine housing (12) and the exhaust gases push the blades of the turbine wheel (6). This causes the turbine wheel and the compressor wheel to turn at a rate up to 70,000 rpm.
Clean air from the air cleaners is pulled through the compressor housing air inlet (4) by the rotation of the compressor wheel (5). The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power. The engine gets more power because the engine is able to burn more air and more fuel during combustion.
The maximum rpm of the turbocharger is controlled by the following items:
- the fuel setting
- the high idle rpm setting
- the height above sea level
| NOTICE |
|---|
If the high idle rpm or the engine rating is higher than given in the Technical Marketing Information (TMI) for the height above sea level at which the engine is operated, there can be damage to engine or to turbocharger parts. Damage will result when increased heat and/or friction due to the higher engine output goes beyond the engine cooling and lubrication system's abilities. |
The bearings (16) and (18) in the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port (11). The oil flows through the passages in the center section for the lubrication of the bearings. The oil flows out of the oil outlet port (17) to the engine lubrication system.
Valve System Components
The valve system components control the flow of inlet air into the cylinders during engine operation. The valve system components control the flow of exhaust gases out of the cylinders during engine operation.
The crankshaft gear drives the camshaft gear. The camshaft gear is in time with the crankshaft gear. The timing provides the correct relationship between the piston and the valve movement.
The camshaft has two lobes for each cylinder. One lobe controls the exhaust valves. The other lobe controls the inlet valves.
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| Illustration 7 | g00327369 |
Valve system components (typical example) (1) Inlet valve bridge (2) Inlet rocker arm (3) Valve pushrod (4) Rotocoil (5) Valve spring (6) Valve guide (7) Inlet valves (8) Lifter (9) Camshaft | |
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| Illustration 8 | g00332964 |
Valve system components (typical example) (1) Inlet valve bridge (2) Inlet rocker arm (7) Inlet valves (10) Exhaust rocker arm (11) Exhaust valve bridge (12) Exhaust valves | |
The camshaft lobes turn and the lifters (8) and (9) move up and down. This movement causes the pushrods (3) to move. The pushrods move the rocker arms (2) and (10) up and down. The rocker arms move the inlet valve bridge (1) and the exhaust valve bridge (11) up and down. The bridges are attached to the cylinder head by dowels. These bridges allow one rocker arm to either open or either close two valves at the same time. There are two inlet valves and two exhaust valves for each cylinder.
Rotocoils (4) cause the valves to turn while the engine is running. Valve rotation provides a longer service life. Valve rotation also minimizes carbon deposits on the valves.
The valve springs (5) cause the valves to close when the lifters move down.