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How Does the Internal Combustion Engine Work?

The internal combustion engine powers most modern cars. But while most people know how to drive a car, not everybody knows what an internal combustion engine involves. In this article, we’ll introduce you to the basics of the internal combustion engine and highlight some of the problems that may cause a car’s engine to function incorrectly. Remember, you don’t have to be a mechanic to understand how a car engine functions.

Let’s start with the basics…

The basic principle of most modern cars is to convert gasoline into motion so that the car can move. To achieve this, gasoline is burnt inside the engine. This is why it’s known as an internal combustion engine; the combustion (basically, another way of saying “burning something”) takes place inside the engine — therefore, you have internal combustion.

When high-energy fuel such as gasoline is burnt inside this enclosed space, a chemical reaction occurs allowing a huge amount of energy to be released. By coming up with a system that allowed this energy release to take place hundreds of times in a single minute, we are able to give our cars the power to move.

Inside the cylinder

In the case of a car, the “enclosed space” in question is known as a cylinder. However, there’s not just one cylinder — generally, there are four, six or even eight in the engine. Inside each cylinder, a four-stroke process takes place in each cycle. These are:

  • The intake stroke — The cylinder is filled with a mixture of gasoline in air.
  • The compression stroke — A cylindrical piece of metal known as a piston then compresses the air, making the forthcoming explosion more powerful
  • The combustion stroke — A spark plug causes a small electric spark, igniting the gasoline. The gasoline then explodes, forcing the piston back down
  • The exhaust stroke — The exhaust valve opens and the exhaust exits the cylinder

As soon as the process finishes, it immediately begins again. This cycle may occur hundreds of times in a single minute.

What can go wrong with a car engine?

There are three main problems that can occur to stop your engine from running:

  • A lack of compression: Your piston rings may be worn out, causing the fuel/air mix to leak past the piston during the compression stroke. Or perhaps the exhaust or intake valves aren’t sealed, which can also create a leak. It may even be as simple as a hole in the cylinder.
  • A lack of spark: Your spark plug may be worn out, meaning the spark is too weak to ignite the fuel. The wiring leading to your spark may also be faulty, causing there to be no spark at all. Or, it could be that the ignition timing is off, meaning that the spark is occurring either too early or too late in the cycle.
  • A bad mix of fuel: If you have a bad fuel mix, it could mean that you’re out of petrol, meaning that there is air entering the engine but no fuel. Without the fuel, combustion cannot take place. Alternatively, there could be too little air due to a clogged air intake. Or perhaps there is an impurity in the mix — water, for example — causing the fuel not to burn.

Alternatively, the problem may not be with the engine at all. If the battery is dead, for example, then the engine will not start. Whatever the case, all of these can be tested with a professional car service, and any problems should be diagnosed and fixed immediately.

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