Twin Turbocharger Arrangement
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| Illustration 1 | g01246591 |
Air inlet system 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 | |
The engine components of the air inlet system and exhaust system control the quality of air that is available for combustion. These components also control the amount of air that is available for combustion. An air cleaner, a turbocharger and an exhaust manifold are on each side of the engine. A common aftercooler is located between the cylinder heads and toward the rear of the engine. The inlet manifold is a series of passages inside the cylinder block. These passages connect the aftercooler to the inlet ports in the cylinder heads. A single camshaft is located in the cylinder block. The camshaft controls the movement of the valve system components.
Both sides of the engine have the same air flow. Turbocharger compressor wheel (5) pulls inlet air through the air cleaner and into air inlet (4). The air is compressed and heated before the air is forced to the aftercooler (2). The aftercooler (2) lowers the temperature of the compressed air. The cooled compressed air passes through the inlet manifold. The air fills the inlet ports in the cylinder heads. Air flow from the inlet port into the cylinder is controlled by the inlet valves. The combustion efficiency increases because of the cooler inlet air. This helps to provide lowered fuel consumption and increased horsepower output.
Each cylinder has two inlet valves and two exhaust valves in the cylinder head. The inlet valves open when the piston moves downward on the inlet stroke. When the inlet valves open, cooled compressed air from the inlet chamber within the inlet manifold is pulled into the cylinder. The piston begins to move up on the compression stroke when the inlet valves close. The air in the cylinder is compressed and the fuel is injected into the cylinder when the piston is near the top of the compression stroke. Combustion begins when the fuel mixes with the air. The force of combustion pushes the piston downward on the power 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 valves close and the cycle begins again.
Exhaust gases from the exhaust manifold (1) flow into the turbine side of the turbocharger. This causes turbocharger turbine wheel (6) to turn. The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through the exhaust outlet (7).
Series Turbocharger Arrangement
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| Illustration 2 | g01246597 |
Air inlet system and exhaust system (1) Exhaust manifold (2) Aftercooler (3) High pressure turbocharger air inlet (4) High pressure turbocharger compressor wheel (5) High pressure turbocharger turbine wheel (6) High pressure turbocharger exhaust outlet (7) Low pressure turbocharger air inlet (8) Low pressure turbocharger compressor wheel (9) Low pressure turbocharger turbine wheel (10) Low pressure turbocharger exhaust outlet | |
The engine components of the air inlet and exhaust system control the quality of air and the amount of air that is available for combustion. There is an air cleaner, two turbocharger and an exhaust manifold on each side of the engine. A common aftercooler is located between the cylinder heads and toward the rear of the engine. The inlet manifold is a series of passages inside the cylinder block. These passages connect the aftercooler to the inlet ports in the cylinder heads. A single camshaft is located in the cylinder block. The camshaft controls the movement of the valve system components.
Both sides of the engine have the same air flow. Air is pulled through the low pressure turbocharger air inlet (7). The air is compressed and heated by the compressor wheel (8) of the low pressure turbocharger. The compressed air is then directed through pipe assembly. The air flows to the high pressure turbocharger air inlet (3) of the high pressure turbocharger. The high pressure turbocharger compressor wheel (4) continues to compress the air. The air is forced into the aftercooler (2). The aftercooler (2) lowers the temperature of the compressed air. The cooled compressed air passes through the inlet manifold. The air fills the inlet ports in the cylinder heads. Air flow from the inlet port into the cylinder is controlled by the inlet valves. The combustion efficiency increases because of the cooler inlet air. This helps to provide lowered fuel consumption and increased horsepower output.
Each cylinder has two inlet valves and two exhaust valves in the cylinder head. The inlet valves open when the piston moves downward on the inlet stroke. When the inlet valves open, cooled compressed air from the inlet chamber within the inlet manifold is pulled into the cylinder. The piston begins to move up on the compression stroke when the inlet valves close. The air in the cylinder is compressed and the fuel is injected into the cylinder when the piston is near the top of the compression stroke. Combustion begins when the fuel mixes with the air. The force of combustion pushes the piston downward on the power 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 valves close and the cycle begins again.
Exhaust gases from the exhaust manifold (1) flow into the turbine side of the high pressure turbocharger. This causes turbocharger turbine wheel (5) to turn. The compressed gases from the high pressure turbocharger enter the turbine side of the low pressure turbocharger turbine wheel (9). The turbine wheels are connected to the shafts that drive the compressor wheels. Exhaust gases from the low pressure turbocharger pass through the low pressure turbocharger exhaust outlet (10) .
Aftercooler
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| Illustration 3 | g01246603 |
Aftercooler (1) Aftercooler (2) Pipe | |
The aftercooler (1) cools the air that comes from the turbochargers. The air then flows into the inlet manifold. The aftercooler is located toward the rear of the engine between the cylinder heads. Coolant from the water pump flows into the aftercooler and through the core assembly. The coolant flows out of the aftercooler through a different pipe. The coolant then flows into the rear of the cylinder block.
The inlet air from the compressor side of the turbochargers flows into the aftercooler through a pipe (2) on each side of the aftercooler housing. This lowers the temperature of the air to approximately 93°C (200°F). The cooler air flows out of the bottom of the aftercooler and into the inlet manifold. The dense air goes into the combustion chambers. This helps to provide lowered fuel consumption and increased horsepower output.
Turbocharger
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| Illustration 4 | g01246605 |
Turbocharger (1) Low pressure turbocharger (2) High pressure turbocharger (3) Exhaust pipe | |
There are two turbochargers (1) and (2) that are installed on each side of the engine. The first turbocharger (high pressure), on each side, is connected to the exhaust manifold. Exhaust gases from the turbine side of the first turbocharger are routed to the turbine side of the second turbocharger (low pressure). The exhaust flows through the exhaust pipe (3). The compressor side of the first turbocharger is connected to the compressor side of the second turbocharger by pipe assembly. The compressed air is then forced into the aftercooler housing.
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| Illustration 5 | g01246608 |
Turbocharger (4) Exhaust inlet (5) Bearing (6) Lubrication passage (7) Bearing (8) Oil outlet port (9) Air outlet (10) Spacer (11) Air inlet (12) Compressor wheel (13) Compressor housing (14) Oil inlet port (15) Thrust collar (16) Thrust bearing (17) Turbine housing (18) Turbine wheel (19) Exhaust outlet | |
The exhaust gases go through the blades of the turbine wheel (18). This causes the turbine wheel and the compressor wheel (12) to turn. The action of the compressor wheel blades causes a compression of the inlet air.
When the load on the engine increases or when a greater engine speed is desired, additional fuel is injected into the cylinders. This creates more exhaust gases, which causes the turbine wheel and the compressor wheel to turn faster. Additional air is forced into the engine as the compressor wheel turns faster. The increased flow of air provides more power to the engine. The engine gets more power because the engine is able to burn additional fuel with greater efficiency.
The maximum rpm of the turbocharger is controlled by the electronic fuel system circuit. The programming of the available fuel amount is done in the personality module. This is done at the factory for a specific engine application.
| NOTICE |
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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 (5) and (7) in the turbocharger use engine oil that is under pressure for lubrication. The lubrication oil for the bearings flows through an oil inlet port (14) and into the lubrication passage (6) in the center section for lubrication of the bearings. The oil exits the turbocharger through an oil outlet port (8) in the bottom of the center section. This oil then returns to the engine lubrication system.
The fuel rack adjustment is done at the factory for a specific engine application. The governor housing is sealed. The following changes are prevented:
- changes in the adjustment of the rack setting
- changes in the high idle speed setting
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 6 | g01246609 |
Valve system components (1) Inlet valve bridge (2) Rocker arm (3) Pushrod (4) Rotocoil (5) Valve spring (6) Valve guide (7) Inlet valve (8) Lifter (9) Camshaft | |
The camshaft (9) turns and the lifter (8) moves up and down. This movement makes the pushrod (3) move the rocker arm (2) up and down. The rocker arm moves the inlet valve bridge (1) and the exhaust bridge (11) up and down. The bridge is attached to the cylinder head by a dowel. The bridge allows one rocker arm to either open or close two valves at the same time. There are two inlet valves and two exhaust valves for each cylinder.
Rotocoil (4) causes the valve to turn while the engine is running. Valve rotation provides a longer service life. Valve rotation also minimizes carbon deposits on the valve.
The valve spring (5) causes the valve to close when the lifter moves down.
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| Illustration 7 | g00332964 |
Valve system components (1) Inlet valve bridge (2) Inlet rocker arm (7) Inlet valves (10) Exhaust rocker arm (11) Exhaust bridge (12) Exhaust valves | |