Petrol engines harness the energy created by petrol in the core of a car engine to propel the vehicle. Petrol is a high-energy fuel that releases large amounts of energy when ignited in an internal combustion engine.
Cars use a four-stroke combustion cycle, or Otto cycle, to convert gasoline into kinetic energy. The four strokes include the intake stroke, compression stroke, combustion stroke and exhaust stroke. The intake stroke starts the combustion process by allowing the engine to take in a cylinder-full of air and gasoline. After this process, air is compressed through the movement of the pistons in the engine. Upon compression, a spark plug emits a spark to ignite the gasoline and causes a controlled explosion in the cylinder. The resulting explosion causes the piston to move downward, which causes the exhaust valve to open and release exhaust out the tailpipe.
Petrol, also known as "crude oil," consists of carbon and hydrogen atoms that split apart when burned. The combustion process in a petrol engine occurs when the carbon and hydrogen combine with oxygen from the air to make carbon dioxide gas and water. Although the petrol engine revolutionized vehicular transport, experts claim it is the cause of pollution and global warming. As a result, hybrid cars that use a combination of electricity and gasoline power are becoming increasingly popular among environmentally-conscious drivers.