How Do Car Engines Work?
Cars are such a vital part of daily life. Whether you have one yourself or use ride-sharing apps, we depend on cars to get us to the grocery store, school and work.
Even though we use these incredible machines on a daily basis, have you ever stopped to wonder how they work?
They may seem overly complicated if you take a peek under the hood, but we’re going to look at each part of the car and see how it works to take you from one location to another.
How Does an Engine Work?
Although a car has metal parts, you can think of it much like the human body. The center of our body is the heart, which pumps blood to our organs and extremities. Similarly, the engine of the car is the core that gives life to the whole structure.
Of course, a car isn’t a living being, so it has to get the energy to function. However, if you remember from physics class, energy cannot be created or destroyed. So, where do cars get energy?
The natural gas you put into your car contains chemical energy found in the molecular bonds. A car engine’s job is to convert that chemical energy into kinetic, or motion, energy.
The process is not quite as simple as it sounds, though. First, the engine must convert the chemical energy to thermal (heat) energy through a burning process. Then, the motor takes that heat and turns it into kinetic energy to move your car.
The above description is a significantly simplified explanation of the process, so let’s look at the steps in detail. However, before we do that, we need to define the different parts of the engine.
The Main Parts of a Car Engine
There are numerous parts of an engine, but we are only going to look at the seven primary parts of the motor.
The engine block is like the skeleton of the motor. You can find most of the other engine parts within this structure.
It has space for the cylinders and pistons, “veins” for oil and water, and compartments for the crankshaft and camshaft.
While the engine block was initially just a piece of metal to hold other engine parts, it has evolved in design over the years. Some older cars have cast iron blocks, while the newest models use aluminum alloy.
The cylinders are one of the most vital parts of a car engine, as they are where the engine converts the energy to a type that it can use to make your car run.
You’ll find the piston at the bottom of the cylinder, which moves up and down in the tube. At the opening of the cylinder, there is a head that controls the intake and output. We’ll talk more about what role each of these pieces has in the creation of kinetic energy.
Number of Cylinders
The number of cylinders in your engine depends on the style and size of the car. You can get anywhere between two to sixteen cylinders in a vehicle, while most will have only four to eight. You don’t always need more cylinders for a powerful car.
The two-cylinder, or twin-cylinder, cars are not very common. However, manufacturers are starting to use them as a more environmentally friendly engine option. A great example of this is the Fiat TwinAir.
Three-cylinder engines are more common than the twin option, but manufacturers mainly use them for smaller vehicles.
If you check how many cylinders your current car has, the chances are that it houses four cylinders. This quantity is the most common number of combustion chambers as it provides the perfect amount of power for mid-range vehicles.
While five-cylinder engines are not very common, six-cylinder motors provide the perfect amount of energy for sports cars.
Eight-cylinder engines have extreme power, and manufacturers are continually pushing the number of cylinders they can fit under the hood. The Cadillac V-16 and the Bugatti Veyron are great examples of cars that have pushed the cylinder capacity to the extreme with a whopping 16 combustion chambers.
Position of Cylinders
Since a car can have any number of cylinders, there are several different standard layouts to make sure they fit under the hood.
Larger cars, like BMWs and Mercedes, organize the cylinders parallel to the vehicle in a straight pattern. Another typical pattern is the inline layout, where the chambers are in a vertical position right next to each other in the engine bay.
Vehicles with more than eight cylinders need to use a “V” outline to allow enough space for all the combustion chambers. Instead of standing upright, they are often at a 60-degree angle.
The cylinder head caps the cylinder and controls what goes in and out of the cylinder. This lid contains two main valves or gates. One lets air and fuel into the cylinder while the other expels the exhaust.
The cylinder head also has a spark plug, which ignites the fuel to start the process of changing the chemical energy into thermal energy.
The pistons are at the bottom of the cylinder. While they have a round edge, they have a flat surface to push fuel and air up the tube.
The pistons move up and down, thanks to the crankshaft that connects them all. Their movement is what keeps the combustion process happening.
The turning crankshaft causes the pistons to move up and down continually. The pistons attach to a connecting rod, which leads to the crankshaft.
The crankshaft and connecting rod are at the bottom of the engine block. You can find them directly below the pistons if the cylinders are in a linear pattern.
Like how the crankshaft regulates the pistons’ movement, the camshaft controls the valves’ opening and closing. Depending on your car’s make and model, you can find this part either within the engine block or on the cylinder heads.
Of course, the crankshaft and camshaft must move in a synchronized manner for the valves to open and close at just the right moment.
The timing belt ensures the synchronized movement of both of these parts. You can identify the timing belt by its appearance, as it looks a lot like your bike chain.
How the Four-Stroke Engine Works
Now that you understand the parts of an engine, it’s time to look at how they all work together.
Your typical car motor is an internal combustion engine.
In simple terms, combustion is the process of turning the chemical energy from the fuel into thermal energy through burning.
Internal combustion engines have a four-step process, or four strokes, that make your car move.
The first step is to allow air and fuel to enter the cylinder through the cylinder head’s intake valve. At this point, the piston moves down to make room for the mixture.
Once there is enough of the mixture inside the cylinder, the valves close, and the piston moves up the cylinder. This step puts extreme pressure on the fuel, preparing it for the next step.
Power or Combustion
Once the piston rises as far as possible in the cylinder, the spark plug sets the gasoline mixture on fire, and it explodes.
Since the cylinder contains the explosion exceptionally well, it only affects the piston. As the expanding gases push it back down, this causes your car to move forward.
The extreme power of the explosion, combined with the rapid combustion cycles happening in all of the engine’s cylinders, is enough to move your car forward.
The final step is to remove the gases from inside the chamber to prepare the cylinders for another combustion cycle. The piston moves back up the tube as the exhaust valve opens, and the gases leave through your exhaust pipe.
Internal Combustion Speed
This whole process happens extremely fast in your car engine. Each vehicle has a specific RPM speed, which stands for rotations per minute. The RPM can range from 1,000 to 20,000 RPM, depending on the car and your acceleration.
Since the complete combustion cycle requires two full piston rotations, you can take your vehicle’s RPM and divide it by two to determine how many cycles each cylinder goes through per minute. If you have a four-cylinder engine
You can then take that number and multiply it by how many cylinders your car houses to find the total sum of combustion cycles per minute in each cylinder.
Take a Look at Your Car’s Engine
With all this knowledge about internal combustion, cylinders, and engines, take a look under the hood of your car. Check how many cylinders it has and how many RPM each one completes.
If you are looking at purchasing a new car, make sure to ask about the engine’s capabilities before buying. Now that you know how an engine works, you can make a more educated purchase!