Combustion engines are the bedrock of the modern industrial age. This simple device has revolutionized the way production works in the modern world. Combustion engines have led to paradigm shifts in the modes of production in nearly every industry after their invention and mass use. They have led to great increases in productivity and efficiency the world over. Combustion engines are also very simple in principle and their usage is actually not rocket science. We will delve deep into the inner workings of a combustion engine and understand the mechanics of its usage.

So, how does an engine work? Let’s start with the basic definition of combustion and work our way upwards from there. A combustion engine is nothing but an engine which generates mechanical power by the combustion from fuel. Combustion engines are of two types. The first is called the Internal Combustion Engine and the second is called The External Combustion Engine. The basic difference between the internal and external combustion engine is based on its mode of operation. In an internal combustion engine, the combustion of fuel occurs with air in a combustion chamber, whereas in an external combustion engine, a working fluid contained internally, is heated by combustion in an external source – through the engine wall or a heat exchanger.

Principles of a combustion engine

The principle behind the mechanics of a combustion engine is simple. If you put high amounts of energy fuels, like gasoline, in a small enclosed space it will generate and set it to ignition, the output will be generation of tremendous amount of energy. Combustion engines borrow the concept of The Pareto Principle when it comes to the ratio of their inputs and outputs. The Italian economist Wilfredo Pareto coined the term Pareto Principle in the 18th Century which says that for an input of 20 percent the output is 80 percent – this concept became famous as “The Pareto Principle” and the combustion energy works on the same concept.

Almost all cars currently use what is called a four-stroke combustion cycle to convert gasoline into motion. The four-stroke approach is also known as the Otto cycle, in honor of Nikolaus Otto, who invented it in 1867. The four stokes are: Intake Stroke, Compression Stroke, Combustion Stroke and Exhaust Stroke. The way these four strokes work is enabled by the parts of a combustion engine. The engine consists of a piston which is connected to a crankshaft by a connecting rod. As the crankshaft revolves here is what happens:

Four strokes in action:


1. The piston is the first one to start – as the intake valve opens the piston moves down to let the engine absorb a cylinder full of air this is the intake stroke.

2. Then the piston moves upwards to compress the mixture of fuel and air this is the compression

3. When the piston reaches the top of its stroke the spark plug emits sparks which ignite the gasoline and the charge in the cylinder explodes driving the piston down.

4. The final stage is when the piston hits the bottom of the stroke, the exhaust valve opens and the exhaust leaves the cylinder to go out.

Finally the engine is ready for the next cycle and it takes another intake of air and gas. This is basically how the combustion engine has powered the entire industrial revolution over the last two centuries.




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