Car Engine: What It Is and How Does Car Engine Work?

Car engines come in all shapes and sizes. There is an endless variety of variations in horsepower, number of cylinders, fuel delivery and even the type of fuel used.

But for all the different types of engines being used today, one thing is consistent across all of them. They all use internal combustion to create energy that makes the engine work.

In this article, we will look at how an car engine works, the different types of car engines and how the technology has evolved over the years.

Key Points

  1. Typically, most car engines today stem from the original Internal Combustion Engines, so the main principle of how an engine works is still the same as when it was invented.
  2. A car engine works by following four steps – intake, compression, combustion, and exhaust.
  3. There are different types of car engines that can be distinguished by their ignition method, the number of strokes per cycle, the specifics of the thermodynamic cycle, the types of fuel used, the number of cylinders, the arrangement of cylinders, or the cooling system.

What Is a Car Engine?

A Brief History of The Car Engine

The Internal Combustion Engine (ICE) started as an experimental design created by a Dutch physicist around 1680. It was not until around 1859 that the first continuously operating Internal Combustion Engine using spark ignition was designed and tested successfully.

Although hailed as a significant achievement at the time, it took another 16 years to deliver working four-stroke Internal Combustion Engines. In 1885 Gottlieb Daimler (Mercedes Benz founder) designed and built the first modern ICE. It is a design that is still in use today. Most modern engines are a direct descendant of the original internal combustion variety.

The engine of an orange car

Types of Car Engines

The typical car engine is commonly referred to as a reciprocating engine, where a piston moves up and down in a cylinder. This type of engine can have one or more cylinders, so this engine design is also known as a piston engine. The spark that the fuel ignites with also further defines the engine classification.

Here’s a more detailed list of car engine classifications by various criteria:

Specifics of the Thermodynamic Cycle

  • Diesel cycle engine. It’s an idealized cycle for diesel engines, consisting of two isentropic processes – an isochoric one and an isobaric one.
  • Otto cycle engine. That one is an idealized cycle for SI engines, consisting of two quasistatic and isentropic processes and two isochoric processes.
  • Dual cycle engine. Also called a mixed or limited pressure cycle, it combines the diesel and otto cycles. The heat is added to a certain extent as a result of the constant pressure process and constant volume.

Ignition Method

  • Spark ignition engine (SI). Spark plugs are crucial for these engines, as they are responsible for the ignition. These mechanical devices ignite the fuel-air mixture that is compressed and combusted inside the combustion chamber.
  • Compression ignition engine (CI). You can find auto ignition or self-ignition in this engine. In the latter one, the fuel charge ignition happens thanks to its own heat of compression. In this case, the air that reaches the combustion chamber is compressed to extremely high pressure, so the compression ratio is very high (even 22).
A man fixing a car engine

Number of Strokes in a Cycle

  • Two-stroke engine. As the name suggests, such an engine needs two piston strokes for its operating cycle to finish – they are a compression stroke and an expansion stroke. It’s also worth noting that it requires just one crankshaft rotation.
  • Four-stroke engine. In this type of engine, four-piston strokes (intake, compression, power and exhaust) are necessary for the operating cycle to be complete. The cycle needs two crankshaft revolutions (720 degrees). Nowadays, the four-stroke engine is the most popular solution.
  • Six-stroke engine. This engine was created to improve the conventional two-stroke and four-stroke engines. It can minimize emissions, boost efficiency, and more. In this case, one of the cylinders makes two strokes, and the rest makes four, so there are six strokes per cycle in total.

Fuel Used

  • Diesel engine. Here, the diesel fuel is used (hence the name), and the fuel ignition happens on its own, without any spark plugs. First, the inlet air mixture is compressed before direct fuel injection.
  • Petrol or gasoline engine. In this kind of engine, the power is produced by burning gasoline (or other volatile liquid fuel that works similarly) ignited by an electric spark. Normally, a fuel-air mixture is applied as a charge.
  • Bi-fuel (dual-fuel) engine. It is an improved variant of the otto engine that can use either natural gas or gasoline thanks to its dual fuelling system.

Cylinder Arrangement

  • Vertical engine. In this type of engine, the piston moves vertically in an up-and-down motion. When it comes to the crankshaft, it is located below the cylinder.
  • Horizontally opposed engine. This engine’s cylinders are set in two banks on either side of one crankshaft – meaning that they share a common crankshaft. It is also sometimes called a “flat engine” or a “boxer engine.”
  • In-line (straight) engine. In this case, all the cylinders are put in one line, that’s why it is called this way. Such engine design is relatively basic and it may use from two to eight cylinders.
  • Radial engine. This reciprocating type of IC engine has cylinders placed outward from the central crankcase. It looks like a star, that’s why it is sometimes referred to as a “star engine.”
  • V-type engine. In this case, an even number of cylinders is placed at such an angle in between them that they form a v-shape. It can be 60-90 degrees.
  • X engine. If you connect two V engines with one crankshaft, you will have an X engine.
  • W engine. The same as with V and X engines, the name stems from the shape resembling a letter. The W engine has more than one (usually three or four) cylinder banks with a single crankshaft.
  • Opposed piston engine. This design consists of pistons co-axial pairs of pistons sharing a common combustion chamber. There is no cylinder head – the cylinder has the piston at both ends.

Cylinder Number

  • Single-cylinder engine. In this simple and compact piston-cylinder configuration, just one engine cylinder is applied.
  • Multi-cylinder engine. As you can probably guess, in this case, multiple cylinders are used – typically, four, six or eight cylinders in various configurations. It is done to achieve more power flow continuation.

Cooling System

  • Water-cooled engine. Such a cooling system uses the passing of water as it goes through the passages provided in every engine block. For this type of engine, water pumps, water jackets, etc. are made.
  • Oil-cooled engine. It is another liquid-based cooling system engine, but in this case, the engine oil plays the role of a coolant to lower heat dissipation. The hot oil is cooled down in the engine with the help of a radiator and then reaches the heat exchanger.
  • Air-cooled engine. In this type of cooling engine, the airflow across the external engine surface is used to prevent heat dissipation. To enlarge the surface area, thin cooling fins are made.
what is car engine?

How Does a Car Engine Work?

The basic operation of the car engine is pretty darn simple. Whether  SI or CI the process that creates the power to drive the pistons involves multiple steps. These steps are;  intake, compression, combustion, and exhaust.

Sounds simple enough on the surface but let’s drill down a bit more to see what is really going on:

How does car engine work
  1. Intake – In this step, a mixture of air and fuel is injected into the cylinder chamber.
  2. Compression – In this step, the piston compresses the fuel and air mixture so that it becomes highly flammable.
  3. Combustion – In this step, a spark ignites the mixture to cause an explosion that pushes the piston down and creates a power stroke in the combustion chamber.
  4. Exhaust – In this step, the burned gasses are eliminated from the combustion chamber through the exhaust system.

Power Supply For Car Engine: Where Engine Power Comes From?

Over the years, the car engine has evolved into a very complex and highly efficient power supply for many different types of cars and trucks. The power output of early engines with six or eight cylinders can now be matched or exceeded by four-cylinder engines. This is due to newer materials and computer-controlled sensors.

Although today’s car engines continue to use the same basic combustion process, power and efficiency are mind-boggling.

Only a few years ago, a Hybrid car with a combination of an ICE and electric motors was unknown. Today, it is commonplace and demonstrates an extremely high level of sophistication and ingenuity by car manufacturers. In a few years, most cars will be some form of Hybrid as this trend is becoming more and more mainstream. It also doesn’t hurt that the cost of Hybrids is getting cheaper, enticing more people to get on the bandwagon.

A car engine bay

What Are Typical Car Engine Problems?

By definition, the internal combustion engine is a mechanical device, so it is prone to mechanical failure. The engine is the heart of the car and as such, is dependent on many other systems to keep it alive and well. Some examples of these other systems include the cooling system, electrical system, fuel delivery system and engine control unit (ECU) system. A problem with any one of these systems could potentially kill the heart of your car.

How Do I know If my Car Engine Has a Problem?

Since your car’s heart is dependent on many other systems to keep it healthy, we have identified the 8 most common problems that will contribute to heart failure:

  1. Will not start – usually, a dead or failing battery is the cause of this problem. If the battery dies then the whole electrical system is dead, and you are not going anywhere.
  2. Overheating – if you have a leak in a cooling system hose or the cooling fan is not working, the engine will overheat. Before the engine reaches the meltdown stage, the check engine light will come on to warn you.
  3. High fuel consumption – could be as simple as a loose fuel cap or as serious as a bad spark plug. Either way, try the cap first and if that’s not the problem, bring your car in for a check-up to identify the issue lowering your engine performance.
  4. Check if the engine light is illuminated – do not ignore this light. It is there to warn you that an ECU sensor has detected a problem in the fuel system. Has it checked out?
  5. Strange noises coming from under the hood – don’t just turn up the radio volume and hope it goes away. Unusual noise is an indication of a potentially serious problem, so check it out.
  6. Oil patches under the car – means there is a leak somewhere in the engine. Bring it to the shop so that they can find and stop the bleeding from the oil pan.
  7. Strong odors of fuel or exhaust (rotten egg smell) – means that there could be a bad o2 sensor. The check engine light will illuminate as well. Bring it in for a check-up.
  8. Car performance has gone downhill – many engine problems could cause this. The best course of action is to take the car in to be checked over by an experienced technician.
The view under a raised car engine hood

Recommendations to Keep Car Engines in Good Condition.

Regular maintenance is the key to ensuring that your car’s engine stays healthy. Whether you can bring the car in for scheduled maintenance or do it yourself, here are the areas to focus on:

  1. Check the oil. That liquid is the lifeblood of your engine so make sure it does not drop into the danger zone. The best way to avoid problems is to change them regularly.
  2. Do not let the engine overheat. Heat is the downfall of a normally healthy engine. If the temperature rises you need to stop, drop and call to get it repaired.
  3. Regular tune-ups. Car engines are designed to be driven thousands of miles between tune-ups. It is unusual but a spark plug can fail so don’t push the limit especially if you notice a problem.
  4. Replace the timing belt. Some cars use a timing chain that is virtually indestructible. But if your car uses a rubber-based belt it will have to be replaced about every 60,000 miles.
  5. Change the air filter. Just like you, your car engine needs to breathe. It takes in oxygen through the air filter so changing it regularly will keep your engine healthy.
  6. Replace drive belts. Some cars have a serpentine belt that runs off the engine to provide power to the alternator and A/C compressor. Some cars use individual belts. Whether one large serpentine or individual belts, make sure you check them for wear (cracking/brittle) regularly.

The Bottom Line

As you can see, the main principle of how an engine works is relatively simple, but it can take different forms. Its exact functioning can depend on the ignition method, number and arrangement of cylinders, cooling system, and many different factors.

To keep your engine up and running for a long time, remember about its regular maintenance and react immediately to any issues you notice. Remember to replace the air filter, the drive belts, or the timing belt, check the oil regularly, and not overheat the engine. Take good care of your car engine, and you will achieve its best performance!

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