Operation of 2 – Stroke Engine

 The two stroke engine only requires two piston movements (one cycle) in order to generate power. The engine is able do produce power after one cycle because the exhaust and intake of the gas occurs simultaneously. There is a valve for the intake stroke that opens and closes due to changing pressures. In addition, due to its frequent contact with moving components, the fuel is mixed with oil to add lubrication, allowing smoother strokes. Working of 2-stroke engine 1) Compression stroke or upward stroke  Piston moves from BDC to TDC  Pushing out the burnt exhaust gases through exhaust port  Fresh fuel-air mixture gets compressed in crankcase 2) Power stroke or downward stroke  Piston moves from TDC to BDC  A high voltage spark is generated by the spark plug  Fresh fuel-air mixture enters into crankcase  Crankcase scavenging takes place ADVANTAGES OF 2 STROKE ENGINE :- Simple design & construction :- It doesn’t have valves. It simply has inlet & outlet ports which makes it simpler. More powerful :- In 2 stroke engine, every alternate stroke is power stroke unlike 4 stroked one in which power gets delivered once every 4 strokes. This gives a significant power boost. Also, the acceleration will be higher & power delivery will be uniform due to same reason. Position doesn’t matter :- 2 stroke engine can work in any position as lubrication is done through the means of fuel (as the fuel passes by through whole cylinder & crankcase). DISADVANTAGES OF 2 STROKE ENGINE :- Less fuel efficiency :- For every alternate power stroke, fuel gets consumed every alternate stroke. This makes the engine less fuel efficient although it results in uniform power delivery. Oil addition could be expensive :- Two-stroke engines require a mix of oil in with the airfuel mixture to lubricate the crankshaft, connecting rod and cylinder walls. These oils may empty your pockets. More pollution :- 2 stroke engine produces a lot of pollution. The combustion of oil added in the mixture creates a lot of smoke which leads to air pollution. Wastage of fuel :- Sometimes the fresh charge which is going to undergo combustion gets out along with the exhaust gases. This leads to wastage of fuel & also power delivery of the engine gets effected. Improper combustion :- The exhaust gases often get trapped inside the combustion chamber. This makes the fresh charge impure. Therefore maximum power doesn’t get delivered because of improper incomplete combustion. Two Strokes Four Strokes It has one revolution of the crankshaft during one power stroke It has two revolutions of the crankshaft during one power stroke It generates high torque It generates less torque Its uses port for fuel’s outlet and inlet It uses valves for outlet and inlet of a fuel Its engines result in lesser thermal efficiency Its engines result in higher thermal efficiency It has a larger ratio in terms of power to weight It has a lesser ratio in terms of power to weight It generates more smoke and shows less efficiency It generates less smoke and shows more efficiency Requires more lubricating oil as some oil burns with the fuel Requires less lubricating oil Due to poor lubrication, more wear and tear occurs Less wear and tear occurs Engines are cheaper and are simple for manufacturing Engines are expensive due to lubrication and valves and are tough to manufacture Engines are basically lighter and are noisy Engines are basically heavier because its flywheel is heavy and are less noisy