3T5-10148-0 Tohatsu REGULATOR, FUEL

Turbocharger
A turbocharger increases the temperature and the density of the air that is sent to the engine cylinder. This condition causes a lower temperature of ignition to develop earlier in the compression stroke. The compression stroke is also timed in a more accurate way with the fuel injection. Surplus air lowers the temperature of combustion. This surplus air also provides internal cooling.A turbocharger improves the following aspects of engine performance:
Power output is increased.
Engine torque is increased.
Engine efficiency is increased.
Illustration 1 g00302786
Components of a turbocharger (typical example)
(1) Air intake
(2) Compressor housing
(3) Compressor wheel
(4) Bearing
(5) Oil inlet port
(6) Bearing
(7) Turbine housing
(8) Turbine wheel
(9) Exhaust outlet
(10) Oil outlet port
(11) Exhaust inlet A turbocharger is installed between the exhaust and intake manifolds. The turbocharger is driven by exhaust gases which flow through the exhaust inlet (11). The energy of the exhaust gas turns the turbine wheel (8). Then, the exhaust gas flows out of the turbine housing (7) through the exhaust outlet (9).Turbine wheel (8) and compressor wheel (3) are installed on the same shaft. Therefore, turbine wheel (8) and compressor wheel (3) rotate at the same rpm. The compressor wheel is enclosed by compressor housing (2). The compressor wheel compresses the intake air. The intake air flows into the engine cylinders through the inlet valves of the cylinders.The oil from the main gallery of the cylinder block flows through the oil inlet port (5) in order to lubricate the turbocharger bearings (4) and (6). The pressurized oil passes through the bearing housing of the turbocharger. The oil is returned through the oil outlet port (10) to the oil pan.The turbocharger has a wastegate. The wastegate is controlled by the boost pressure. This allows some of the exhaust gases to bypass the turbine wheel at higher engine speeds. The wastegate is a type of flapper valve that automatically opens at a preset level of boost pressure in order to allow exhaust gas to flow around the turbine. The wastegate allows the design of the turbocharger to be more effective at lower engine speeds.Cylinder Head And Valves
Illustration 2 g00905459
Cross section of the inlet and exhaust valves in the cylinder head (typical example)
Illustration 3 g00905464
Cylinder head and valves (typical example)
(1) Collets
(2) Valve spring retainer
(3) Valve spring
(4) Valve seal
(5) Valve guide
(6) Cylinder head
(7) Cylinder head gasket
(8) Pushrod
(9) Lifter
(10) Exhaust valve
(11) Inlet valve The valves and the rocker shaft assembly control the flow of air into the cylinders and out of the cylinders during engine operation. The cylinder head assembly has two valves for each cylinder. Each valve has one valve spring (3). The ports for inlet valve (11) and exhaust valve (10) are on the left side of the cylinder head.The valve moves along a steel valve guide (5). The valve guides can be replaced.The inlet valve and the exhaust valve are opened and closed by the rotation and movement of the following components:
Crankshaft
Idler gear
Camshaft
Valve lifters
Pushrods
Rocker arms
Valve springsThe camshaft gear is driven by the idler gear. The camshaft gear, the idler gear and the crankshaft gear are timed together. When the camshaft turns, the valve lifters are moved up and down. The pushrods move the rocker arms. The rocker arms make the inlet valves and the exhaust valves open and close. This is in sequence with the firing order of the engine. The valve springs force the valves back to the closed position.