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Petrol Engine: Two stroke Vs Four Stroke Petrol Engine

Petrol Engine:


Petrol Engine: Petrol Engine is an internal combustion system which has Spark-Ignition. this type of engine is developed in 1876 by Nikolaus August Otto.(after many attempts done by many members).
This engine has more speed ratio than the diesel engine. in the petrol engine, the thermal efficiency is half of the diesel engine.
In this, the piston is connected very close in the cylinder.
It compresses the mixture of fuel and air to ignite the mixture spark plug is used.
This engine has a spark plug, to produce a spark in it, there is a need for high voltage current, this is done by the ignition coil.
In this, the reciprocating parts are not heavy than diesel. in this, the stroke length is less than the diesel and petrol engine produce high RPM and speed of flame is high.
Petrol has less energy density than diesel.
It exhausts more heat than the diesel engine. Most of these engines are provided with a water cooling system.

Types of petrol engines:

There are Two types of Petrol Engine Two Stroke Petrol Engine and Four Stroke Petrol Engine.The detailed explanation about Two Stroke Petrol Engine and Four Stroke Petrol Engine is explained as follows.

Two Stroke petrol engine:

  • In the two-stroke engine the complete cycle is done in two strokes.this has high power to weight ratio, and it has low thermal efficiency.
  • For each revolution of crankshaft one power stroke is needed.
  • In this type, the work is done simultaneously, which intake and exhaust are done at the end of combustion and start of compression.
  • This type of engines is mostly used for less weight and high power to weight ratio.
  • Two stroke engine has less parts due to this it has lesser less weight and for every one revolution it fires and gives multiple power than four stroke.
  • This produces more pollution than four-stroke.
  • It has no valves, it is presented with ports in the cylinder.
  • in this crankcase is fully airtight.
  • in this flywheel is smaller than four-stroke.

Four Stroke petrol engine:

  • In four stroke it has Intake, Compression, Combustion, and Exhaust strokes.
  • This is completed in two revolutions of a crankshaft. this has valves to control inlet and exhaust flow.
  • For every two revolutions of crankshaft one power stroke is needed.
  • The process starts at Intake which is used to draw the air and fuel(which is vaporized).
  • Compression is done to ignite the air and fuel by compressing.
  • Combustion: It pushes the piston towards down by combustion of fuel.
  • Exhaust stroke: The exhaust gases are pushed out of the cylinder by upward motion.
  • Flywheel size is larger than a two-stroke.
  • In four stroke fuel is completely consumed.
  • it produces less pollution than a two-stroke.
  • It has high thermal efficiency than a two-stroke.



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