All You Need to Know About The Four-Stroke Engine And Its Working

The four-stroke petrol engine is the most common engine used in automobiles, also known as the gasoline engine. Today these are widely used in bikes, cars as power units. In this post, we will explain the working principle of a four-stroke engine.

Our daily activities require energy to be transferred from one object to another, sometimes as heat and sometimes as work. Energy transfer of the heat is simple. For example, burning fuel discharges its chemical energy directly into the surrounding area as heat, but it’s not very easy to discharge chemical energy of fuel as a work.

To do that, we require a heat engine. A heat engine is a device that transforms chemical energy or fuel into thermal energy and then utilizes this thermal energy for mechanical work. Now, we shall see how the thermal energy of the fuel is converted to the mechanical world in full stroke by total engines.

A four-stroke engine is an internal combustion engine with a spark-ignition designed to run petrol and similar volatile fuels. A spark-ignition engine air-fuel is ignited by an electric spark generated by a spark plug.

The making of a four-stroke petrol engine depends on the following parts:


It is a cylindrical container in which the piston reciprocates.

Connecting rod

A connecting rod interconnects the piston and crankshaft and transmits the forces from the piston to the crankshaft.

Tang shaft

Tang shaft converts the reciprocating motion of Pistons into proper rotary motion of the output shaft. The big end of the connecting rod connects to the crank and can freely rotate on the crank.

Gudgeon pin

The smaller end of the connecting rod is connected to the piston using a gudgeon pin, and the connecting rod can swirl around the gudgeon pin.


A piston is placed inside the double cylinder diesel engine. So that it can have only sliding motion in one direction.

The resulting mechanism is known as the Slider crank mechanism. It converts the linear motion of the slider into the rotary motion of the crank.


Valves are provided either on the double cylinder diesel engine head or the side of the cylinder.


The top dead center or TDC’s position of the piston is farthest from the crankshaft. The bottom dead center or BDC’s position of the piston when it is nearest to the crankshaft. This action, too, prefers the full travel of the piston along with the cylinder in either direction.

Overview of working of a four-stroke engine

Four-stroke engines are engines that provide a variety of different appliances to cars and motorbikes. To run smoothly and effectively, they make use of strokes called distinct piston strokes.

If you are working as a technician in any company, it’s mandatory to know about the working or mechanism of a four-stroke engine. People who work as technicians have a standard work to engage with a variety of engines. They can be successful if they know the main key points or essential keys or the differences about the engines.

We can say that four-stroke engines are a modified version of internal combustion engines. Usually, vehicles with gas or diesel as fuel use four-stroke engines as their engines.

During the working of engines, pistons play a vital role and pass through 4 phases to obtain a power cycle. During these phases, pistons will move upwards and downwards to achieve the cycle. Once the piston completes its action, it begins again for another cycle.

An introductory lesson in the fundamentals of a four-stroke gas engine may be helpful to your understanding of mercury products. Here are the essential components of every four-stroke gas engine: a piston, a connecting rod, and a crankshaft as the piston travels up and down in the double cylinder diesel engine, and this lateral motion turns into a rotating motion at the crankshaft.

The longer the stroke of the piston, the larger the displacement of gas occurs in the double cylinder. To propel that piston, we need to ignite a tiny bit of gas and a whole lot of air that creates expansion inside the cylinder.

The fuel delivery system consists of an air intake manifold. Valves intake and exhaust a fuel injector and a spark plug. A four-stroke engine is called a four-stroke because up and down motions are needed to complete the cycle.

Functioning of four-stroke engines 

1.The action of the First stroke

The piston travels downward as the intake valve opens in a mixture of air from the atmosphere in the first stroke. A metered amount of gas from an electronic fuel injector enters the double cylinder diesel engine; this is called the intake stroke or the First stroke.

2.The action of the Second stroke

On the second stroke, the piston travels upward, compressing the air and fuel to make a highly explosive mixture. This process is called the compression stroke or the Second stroke.

3.The action of the Third stroke

At this point of the third stroke, the spark plug fires send the piston downward from the expansion of the air and gas mixture. It is the combustion stroke or the third stroke.

4.The action of the Fourth stroke

The fourth stroke is otherwise called the exhaust stroke. As the piston travels, the exhaust valve upward opens to release the burned air-fuel mixture; when the piston reaches the top of this stroke, the intake valve opens, and the cycle begins all over again.

Process of a four-stroke engine

It takes one up-and-down motion or two strokes of the piston to create one revolution of the crankshaft. RPMs or revolutions per minute is how many times the crankshaft rotates within that minute. At wide-open throttle, the crankshaft may turn at 5,000 rpm or a dizzyingly eighty-three times per second.

Meanwhile, the piston traveled up and down 166 times in that exact second. Now you will see how fast that’s, and it runs as fast as any double cylinder diesel engine. We can see it running amazingly, again and again. The four-stroke engine does this smoothly, quietly, and reliably for years and years of operation.


Thus, in this article, we have discussed the four-stroke engine and it’s working. People must know the mechanism of the four-stroke engine to avoid mishaps in the future.


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