Ignition system of Petrol Engine

The ignition system of Petrol Engine

The ignition in a petrol engine takes place by means of a spark plug at the end of the compression stroke. The voltage required to produce a spark across the gap between the sparking point of the plug is 6000 to 10000 volts.

The following two ignition system of petrol engines are important,…

  1. Coil ignition system (also known as battery ignition system)
  2.  Magneto ignition system.

The coil ignition system has an induction coil, which consists of two coils known as primary and secondary coils wound on a soft iron core. one end of the primary coils is connected to the ignition switch, ammeter, and battery generally of 6 volts. The other ends of the primary coil are connected to a condenser and contact breakers. A condenser is connected across the contact breaker for the following two reasons.

a) It prevents sparking across the gap between the points.
b) It causes a more Rapid break of the primary current a higher voltage in the secondary circuit.

The secondary coil is connected to a distributor( in a multi-cylinder engine) with the Central Terminal of the sparking plugs. The outer terminals of the sparking plugs are earthed together and connected to the body of the engine.

The coil ignition system is employed in medium and heavy Spark ignition engines such as in cars.

The Magneto ignition system has the same principle of working like as that of the coil ignition system except that no batteries required as the Magneto acts as its own generator. This type of ignition system is generally employed in small spark-ignition engines such as a scooter, motorcycles, and motorboat engines.


Spark plug:- a spark plug is a device used to produce Spark for ignition the charge of petrol engines. It is always screwed into the cylinder head. It is usually designed to wheat stand a pressure up to 35 bar and operated under a current of 10000 to 30000 volts. The spark plug gap is kept from 0.3 mm to 0.7 mm



Please follow and like us:

Leave a Comment