0333669 EVINRUDE ORIFICE, High speed, No. 74D, 200STL

Illustration 1 g03823329
(1) Inlet Valves
(2) Exhaust Valves
(3) Water Cooled Exhaust Manifold
(4) Water Inlet for the Aftercooler
(5) Water Outlet for the aftercooler
(6) Aftercooler
(7) Air Inlet
(8) Exhaust Outlet
(9) Compressor
(10) Turbine
(11) Air Cleaner The components of the air inlet and exhaust system control the quality of air and the amount of air that is available for combustion. The components of the air inlet and exhaust system are the following components:
Air cleaner
Turbocharger
Aftercooler
Cylinder head
Valves and valve system components
Piston and cylinder
Water Cooled Exhaust manifold Inlet air is pulled through the air cleaner (11) into air inlet (7) by turbocharger compressor wheel (9). The air is compressed and heated to about 200° C (392° F) before the air is forced to the aftercooler (6). As the air flows through the aftercooler, the temperature of the compressed air lowers to about 43 °C (110 °F). Cooling of the inlet air increases combustion efficiency. Increased combustion efficiency helps achieve the following benefits:
Lower fuel consumption
Increased horsepower outputFrom the aftercooler, air is forced into the inlet manifold. Air flow from the inlet chambers into the cylinders is controlled by inlet valves (1). There are two inlet valves and two exhaust valves (2) for each cylinder. The inlet valves open when the piston moves down on the intake stroke. When the inlet valves open, cooled compressed air from the inlet port 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 water-cooled exhaust manifold (3) as the piston rises on the exhaust stroke. After the exhaust stroke, the exhaust valves close and the cycle starts again. The complete cycle consists of four strokes:
Inlet
Compression
Power
ExhaustExhaust gases from water-cooled exhaust manifold (3) enter the turbine side of the turbocharger in order to turn turbocharger turbine wheel (10). The turbine wheel is connected to the shaft that drives the compressor wheel. Exhaust gases from the turbocharger pass through exhaust outlet (8), a muffler, and an exhaust stack.Turbocharger
Illustration 2 g03823382
Water-cooled turbocharger
(1) Air inlet
(2) Exhaust outlet
(3) Exhaust inlet
(4) Compressor housing
(5) Compressor wheel
(6) Bearing
(7) Oil Inlet port
(8) Bearing
(9) Water-cooled turbine housing
(10) Turbine wheel
(11) Oil outlet port All of the air that enters the engine passes through the turbocharger. All of the exhaust gases from the engine pass through the turbocharger.The exhaust gases enter water-cooled turbine housing (9) through exhaust inlet (3). The housing of the turbochargers turbine is water cooled. This prevents the heat of the exhaust gases from radiating into the environment that surrounds the engine. The exhaust gas pushes the blades of the turbine wheel (10). The turbine wheel is connected by a shaft to the compressor wheel (5).Air that passes through the air filters enters the compressor housing air inlet (1) by the rotation of compressor wheel (5). The compressor wheel causes the inlet air to be pushed into the inlet side of the engine. Boost pressure is caused when the compressor wheel pushes more air into the inlet side of the engine. This results in a positive inlet manifold pressure that exceeds atmospheric pressure. This allows the engine to burn more fuel. When the engine burns more fuel, the engine produces more power.When the throttle is opened, more fuel is injected into the cylinders. The combustion of this additional fuel produces greater exhaust temperature. The additional exhaust temperature causes the turbine and the compressor wheels of the turbocharger to turn faster. As the compressor wheel turns faster, more air is forced into the cylinders. The increased flow of air gives the engine more power by allowing the engine to burn the additional fuel with greater efficiency.Bearings (6) and (8) for the turbocharger use engine oil under pressure for lubrication and cooling. The oil comes in through oil inlet port (7). The oil then goes through passages in the center section in order to lubricate the bearings. This oil also cools the bearings. Oil from the turbocharger goes out through oil outlet port (11) in the bottom of the center section. The oil then goes back to the engine oil pan.
Illustration 3 g03823388
Turbocharger with wastegate
(12) Canister
(13) Actuating lever
(14) Line (boost pressure) The operation of the wastegate is controlled by the boost pressure. At high boost pressures, the wastegate opens in order to decrease boost pressure. At low boost pressure, the wastegate closes in order to increase boost pressure. When the engine is operating under conditions of low boost, a spring pushes a diaphragm in canister (12). This action moves actuating lever (13) in order to close the valve of the wastegate. Closing the valve of the wastegate allows the turbocharger to operate at maximum performance.As the boost pressure through line (14) increases against the diaphragm in canister (12), the valve of the wastegate is opened. When the valve of the wastegate is opened, the rpm of the turbocharger is limited by bypassing a portion of the exhaust gases. The exhaust gases are routed through the wastegate which bypasses the turbine wheel of the turbocharger.Note: The turbocharger with a wastegate is preset at the factory and no adjustment can be made.Bearings (6) and (8) for the turbocharger use engine oil under pressure for lubrication and cooling. The oil comes in through oil inlet port (7). The oil then goes through passages in the center section in order to lubricate the bearings. This oil also cools the bearings. Oil from the turbocharger goes out through oil outlet port (11) in the bottom of the center section. The oil then goes back to the engine oil pan. Valve System Components
Illustration 4 g03823568
(15) Rocker arm
(16) Pushrod
(17) Valve bridge
(18) Valve spring
(19) Valve
(20) Lifter The valve system components