ICE CH 6 By: Dr. Assim Adaraje

Timing Diagram for a 4-stroke Petrol Engine

TWO – STROKE ENGINE PORT TIMING

& SUPERCHARGING

& COMBUSTION

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Actual Indicator Diagram of a 4-stroke Petrol Engine

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Gasoline Engine Valve Overlap: The duration (10o + 10o = 20o) when both the inlet and exhaust valves remain open is called valve overlap. Spark Advance: The ignition is initiated 20 – 30o before TDC. This is called spark advance.

Valve timing for two stroke diesel engine Valve timing diagram

Two Stroke timing diagrams: timing diagrams are self-explanatory

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SUPERCHARGING The power and efficiency of an internal combusting engine can be increased with the use of an air compression device such as a supercharger or turbocharger. Increasing the pressure and density of the inlet air will allow additional fuel to be induced into the cylinder, increasing the power produced by the engine. Superchargers and turbochargers are used extensively on a wide range of diesel engines, since they are not knock limited. SI engines are knock & compressor pressure limitation. 6

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Looking at the difference between the two the supercharger will take its power from the crankshaft whereas the turbocharger will draw power from exhaust gases that result from combustion. Superchargers will spin with speeds up to 50,000 RPM. The turbocharger is not connected to the engine and can spin much faster. 8

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CH. 7

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