Learn Automobile: Four-stroke engine


Automobile is one of the important Technologies of our daily life. Today we will learn Four-Stroke Engine, presenting by Mr. Sad Abdul Wasea, he is developing some content for e-Learningbd.com Team. We want to learn something. Ok, let’s go.

A car engine is one of the most amazing machines, we use on a daily basis. Four-stroke engine is one vital machine in a vehicle. In this article, we’ll discuss the basic idea behind an engine a­nd then go into detail about how all the pieces fit together, what can go wrong and how to increase performance.



The four-stroke engine was first demonstrated by Nikolaus Otto in 1876, it is also known as the Otto cycle. The technically correct term is actually four stroking cycle. The four stroke engine is probably the most common engine type nowadays. It powers almost all cars and trucks.

Stroke refers to the movement of the piston in the engine. The four strokes of the cycle are intake, compression, power, and exhaust. Each corresponds to one full stroke of the piston; therefore, the complete cycle requires two revolutions of the crankshaft to complete.

4 strokes engine

The four separate strokes are termed:

Intake Stroke: The intake stroke, the piston moves down, drawing a fresh charge of vaporized air or fuel mixture. Represent engine features a poppet intake valve which is drawn open by the vacuum produced by the intake stroke.

Compression Stroke: As the piston rises, the poppet valve is forced shut by the increased cylinder pressure. Flywheel momentum drives the piston upward, compressing the fuel/air mixture. With both intake and exhaust valves closed, the piston returns to the top of the cylinder compressing the air or fuel-air mixture into the cylinder head.

Power Stroke: At the top of the compression stroke, the spark plug fires, igniting the compressed fuel. As the fuel burns it expands, driving the piston downward.

Exhaust Stroke: At the bottom of the power stroke, the exhaust valve is opened by the cam/lifter mechanism. The upward stroke of the piston drives the exhausted fuel out of the cylinder. This action expels the spent fuel-air mixture through the exhaust valve.


Now the engine is ready for the next cycle, so it intakes another charge of gas and air. The motion that comes out of an internal combustion engine is rotational, while the motion produced by a potato cannon is straight line. In an engine the linear motion of the pistons is converted into rotational motion by the crankshaft. The rotational motion is nice because we plan to turn the car’s wheels with it anyway. Now let’s look at all the parts that work together to make this happen, starting with the cylinders.

Leave a comment

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>