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| Illustration 1 | g00411724 |
Air Inlet and Exhaust System Components (1) Aftercooler (2) Air inlet (3) Turbocharger compressor wheel (4) Inlet valves (5) Exhaust valves (6) Turbocharger turbine wheel (7) Exhaust outlet (8) Inlet manifold (9) Exhaust manifold | |
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| Illustration 2 | g00411725 |
Air inlet and exhaust system components (2) Air inlet (7) Exhaust outlet (8) Inlet manifold (9) Exhaust manifold (10) Valve mechanism cover (11) Turbocharger (12) Oil inlet line (13) Oil drain line | |
The components of the air inlet and exhaust system control the quality of the air that is available for combustion. These components also control the amount of the air that is available for combustion. The system includes all the components in the illustrations plus an air cleaner.
Inlet air is pulled through the air cleaner into air inlet (2) by turbocharger compressor wheel (3) . The air is compressed, heated, and pushed through the aftercooler (1) . The temperature of the air is lowered while the air flows through the aftercooler. Cooling of the inlet air increases combustion efficiency. Increased combustion efficiency helps to lower fuel consumption. Also, increased combustion efficiency helps to increase the horsepower output.
From the aftercooler, air is forced into inlet manifold (8) . Air flow from the inlet chambers into the cylinders is controlled by inlet valves (4) . There are two inlet valves and two exhaust valves (5) in the cylinder head for each cylinder. Inlet valves open when the piston moves down on the intake stroke. When the inlet valves open, cooled compressed air from the inlet chamber within the inlet manifold is pulled into the cylinder. The inlet valves close and the piston begins to move up on the compression stroke. The air in the cylinder is compressed. 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. During the power stroke, the combustion force pushes the piston downward. The exhaust valves open and the exhaust gases are pushed through the exhaust port into exhaust manifold (9) .
After the piston makes the exhaust stroke, the exhaust valves close and the cycle starts again. The complete cycle consists of four stages:
- inlet stroke
- compression stroke
- power stroke
- exhaust stroke
Exhaust gases from the exhaust manifold enter the turbine side of the turbocharger in order to turn the turbocharger turbine wheel (6) . The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through exhaust outlet (7) , a muffler and an exhaust stack.
Turbocharger
The turbocharger is mounted to the exhaust manifold of the engine. All the exhaust gases go from the exhaust manifold through the turbocharger.
The exhaust gases go into the turbocharger. The exhaust gases then push the blades of the turbocharger turbine wheel. This causes the turbocharger turbine wheel to spin. Because the turbocharger turbine wheel is connected by a shaft to the turbocharger compressor wheel, the compressor wheel can turn at very high speeds. Clean air from the air cleaner is pulled through the compressor housing air inlet by rotation of the compressor wheel. The action of the compressor wheel blades causes a compression of the inlet air. This compression gives the engine more power by allowing the engine to burn more air and fuel during combustion.
When the load on the engine increases, or a greater engine speed is desired, more fuel is injected into the cylinders. This makes more exhaust gases that cause the turbine and compressor wheels of the turbocharger to turn faster. As the compressor wheel turns faster, more air is forced into the engine. The increased flow of air gives the engine more power by allowing the engine to burn the additional fuel with greater efficiency.
Maximum rpm of the turbocharger is controlled by the electronic control module. The electronic control module controls the available fuel amount. The programming in the electronic control module is preset at the factory for a specific engine application.
Bearings in the turbocharger use engine oil under pressure for lubrication. The oil comes in through the oil inlet port. The oil then goes through passages in the center section in order to lubricate the bearings. Oil from the turbocharger goes out through the oil outlet port and oil drain line. The oil then goes back to the engine lubrication system.
Some turbochargers use a waste gate. The waste gate is controlled by boost pressure. At high boost pressures, the waste gate opens. To increase boost pressure at low boost pressures, the waste gate closes. With this arrangement, the turbocharger can be designed to be more effective at lower engine speeds.
The opening pressure of the waste gate is 165 ± 3 kPa (24 ± .5 psi).
Valve Mechanism
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| Illustration 3 | g00411726 |
Valve System Components (1) Inlet bridge (2) Rotocoil (3) Rocker arm for inlet valve (4) Pushrod (5) Valve springs (6) Inlet valves (7) Valve guide (8) Camshaft (9) Lifter | |
The valve system components control the flow of inlet air into the cylinders during engine operation. The valve system components also control the flow of exhaust gases out of the cylinders during engine operation. The inlet and exhaust valves are opened and closed by the valve mechanism as rotation of the crankshaft causes rotation of camshaft (8) . The camshaft gear is driven by an idler gear which is piloted in the cylinder block and bolted through the timing gear housing to the block. The idler gear is driven by the crankshaft gear. The camshaft must be timed to the crankshaft in order to get the correct relation between the piston movement and the valve movement.
The camshaft has three camshaft lobes for each cylinder. Two lobes operate the inlet and exhaust valves, and one operates the unit injector mechanism. As the camshaft turns, the camshaft lobes cause lifter (9) to move pushrod (4) up and down. Upward movement of the pushrod against the rocker arm for the inlet valve transfers a downward force on inlet bridge (1) . This force opens two inlet valves (6) . The inlet bridge moves up and down on a dowel. The dowel is mounted in the cylinder head.
Each cylinder has two inlet and two exhaust valves. Two valve springs (5) for each valve hold the valves in the closed position when the lifter moves down.
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| Illustration 4 | g00411800 |
Valves The following rocker arms are removed from the number two cylinder: inlet, exhaust and unit injector . (1) Inlet bridge (2) Rotocoil (3) Rocker arm for inlet valves (6) Inlet valves (10) Exhaust rocker arm (11) Exhaust bridge (12) Exhaust valves | |
Rotocoils (2) cause the valves to rotate while the engine is running. The rotation of the valves keeps the carbon deposits on the valves to a minimum. Also, the rotation gives the valves longer service life.