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How Does a Car Engine Work?

Darrek Olson
How Does a Car Engine Work?

Why does your car go vroom? You may be surprised to know that a rapid series of explosions inside a metal box pulls you along in your car. This metal “magic” box is called the engine!

Car Engine

What is an engine?

Most modern cars use an internal combustion engine (ICE). Internal combustion engines convert fuel into motion via explosions inside themselves.  The motion generated by the engine is then used to perform some sort of task, such as turning the wheels of your car, the blade of your chainsaw, or to generate electricity for your house when the power goes out.

How does an internal combustion engine work?

Modern internal combustion engines work via the four-stroke cycle. This means that there are four “strokes” that a piston moves through inside the engine to get its job done. The four strokes are intake, compression, combustion, and exhaust. Let’s dig into those a bit deeper.

Internal Combustion


The intake stroke begins with the piston at a position very near the valves called top dead center (TDC). During the intake stroke, the intake valve opens, the exhaust valve closes, and the piston is pulled by the crankshaft away from the intake valve. This creates a vacuum inside the cylinder which causes air to enter the cylinder. In some vehicles, gasoline has already been injected into this air; in others, the gasoline is directly injected into the cylinder. This works just the same as how we breathe; our diaphragm moves down creating a vacuum in our lungs which draws air in.


Once the piston travels as far away from the valves as possible, or bottom dead center (BDC), the intake valve closes. This traps the air and fuel inside the cylinder so it can’t escape. Simultaneously, the piston makes its way back towards the valve, causing the air-fuel mixture to compress.

Combustion (or Power)

Once the piston reaches near TDC again, the spark plug ignites the compressed fuel-air mixture, causing it to explode and expand rapidly and push the piston towards BDC. This is the stroke that actually performs the work in the engine; the other three are just means to make this explosion happen.


After the combustion/power stroke, the cylinder is full of a number of gases created from the explosion that just happened. To rid the engine of this, the piston again travels toward TDC while the exhaust valve simultaneously opens to allow the gases to escape from the engine. The piston pushes these gases out of the engine through the open exhaust valve. Once the piston reaches TDC, the intake stroke will start once again and the whole process continues until the engine is shut off.


Now that we know how the engine generates power, how do we control it? Engines can only generate power relative to the amount of air and fuel they receive. The amount of air that travels into the engine is controlled by the throttle, which is basically just a flap in the intake tube. It can rotate to let a lot or a little air in at a time. The throttle is connected to the driver via the accelerator pedal. This gives the driver control over how much power the engine produces at any time, which in turn determines whether the car accelerates, decelerates, or stays at a constant speed.


Why do we use gasoline engines?

People traveled with horses for centuries until it became cheaper and easier to have a car (and much less… messy), and numerous different types of cars have come and gone. Gasoline engines have been around since the late 19th century, but other types were also available at that time and even beforehand. Steam cars were more difficult to operate and less reliable than gasoline engines by the 1930s. Electric cars were very popular in the early 20th century, but the short range and long charging times of electric along with the growing gasoline infrastructure all but killed off electric vehicles until recently.

Will cars continue to use gasoline engines in the future?

With the increase in popularity of electric vehicles again, this question arises frequently. Gasoline vehicles will still be available for the foreseeable future. This is due to, just like in the past, the relatively short range of electric vehicles which is currently around 250 miles. In comparison, gasoline engines get up to 750 miles, three times the distance, and the time required to fuel up vs charge is much less. However, battery technologies are ever increasing. It’ll be interesting to see what the vehicle market looks like in five years.

Tesla Charging Station

Now that you know how gasoline engines work, maybe it’s time to feel how a new one works! Check out new vehicle listings on Carsforsale.com today!

Darrek Olson
Darrek Olson

Darrek is an enthusiast driver who values the journey more than the destination. A self-proclaimed Miata fanboy, his obscure knowledge of cars sometimes prevents him from remembering what he had for breakfast.

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