Understanding petrol engine

The word petrol sounds quite popular in terms of usage in a vehicle. Most people don’t understand how and what it takes for an engine to move via petrol, thus it’s named “Petrol Engine”. This article will be exposing you to the definition, working, efficiency, history, diagram, and components of a petrol engine. You’ll also get to know the difference between petrol and diesel engine. Previously, some articles were published on an automobile engine. Checkout!


What is a petrol engine?

A petrol engine is a type of internal combustion engine with spark ignition (spark plug), which uses petrol and similar volatile fuel to run the engine. Petrol engines which are known as the gasoline engine in American English were invented in 1976 in Europe. It was first built in 1876 in Germany by Nikolaus August Otto, though there had been attempts by Etienne Lenoir, Siegfried Marcus, Julius Hock, and George Brayton.

The earlier petrol engine is designed to pre-mixed fuel and air before compressing, which occurs in the carburetor. However, it is now done by electronically controlled fuel injection. Well, the process differs in a small engine where the cost or complication of electronics does not suit the engine’s efficiency.

Applications, advantages, and disadvantages of petrol engines

diagram of petrol engine

Gasoline engines rotate at higher rotation speeds than diesel, partially due to their lighter pistons, connecting rods, and crankshaft (a design efficiency made possible by lower compression ratios) and due to petrol burning more quickly than diesel. Because pistons in gasoline engines tend to have much shorter strokes than pistons in diesel engines, typically it takes less time for a piston in a petrol engine to complete its stroke than a piston in a diesel engine.

However, the lower compression ratios of petrol engines give them lower efficiency than diesel engines. Typically, most gasoline engines have approximately 20%(avg.) thermal efficiency, which is nearly half of the diesel engines. However, some newer engines are reported to be much more efficient (thermal efficiency up to 38%) than previous spark-ignition engines.

Watch the video below to learn the working of a petrol engine:

The process differs from a diesel engine in the method of mixing the fuel and air, and in using spark plugs to initiate the combustion process. In a diesel engine, only air is compressed, and the fuel is injected into very hot air at the end of the compression stroke, and self-ignites. Before the widespread of diesel engines, gasoline engines were used on trucks, buses, and some railway locomotives. Finally, Petrol engines may run on the four-stroke cycle or the two-stroke cycle.

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