What is Engine? Definition, Parts, Working, Types, Equation, Maintenance

Knowing how an engine works and what it’s made of is a big deal if you’re an engineer, mechanic, or automotive enthusiast. But if you’re not familiar with the ins and outs of how these power plants work, it can be challenging to understand what they are and how they operate. Here are with

What is Engine? Definition

Engine Definition

An engine converts one form of energy (fuel) into mechanical energy. It can also refer to a device that converts one form of energy into another. For instance, an electric generator converts mechanical energy into electrical energy, and an optical fibre transforms light into an electric current—see the photoelectric effect.

Engines are typically driven by energy released from the combustion of fuels. Still, other energy sources (such as electricity, magnetism, nuclear power, or even moving water) have been used to drive engines.

Brief Introduction of Engine

The engine of a vehicle is used to create motion. The engine converts energy from another source, such as burning fuel or using an electric battery, into mechanical energy that then causes the vehicle to move.

Engines are typically designed to achieve higher efficiency and more power than human muscle. They are made in various sizes and shapes, ranging from tiny micro engines to large.

The essential parts of an internal combustion engine include the block, cylinder head, valves, pistons, and piston rings. The cylinder head houses the valves that let air and fuel mixture into the machine. The valves open and close at the right time for optimal power production.

The pistons are connected to the crankshaft by piston rings that keep them from falling as they move up and down inside the cylinder block. The pistons push on the air and fuel mixture in the cylinder to expand rapidly. This creates a small explosion on the piston, moving back up again. The movement is transferred to the crankshaft through a connecting rod.

This simple system works in most engines, but different variations on this basic setup allow for more significant power generation (or efficiency). Some machines run on dual or triple cylinders, while others use more complex combinations of valves, called camshafts. Most large engines have a cooling system that

Most engines are powered by a chemical reaction that converts fuel to heat, then used to create motion.

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History of Engine

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. When used for propulsion of ships, locomotives, or tractors, they are referred to as a steam engine (marine), steam locomotive, or steamer (railroad)

The first machine to be called an engine was designed by Hero of Alexandria around the 3rd century BC and was made of wood and used steam pressure to propel at least one wheel. In 1698 Thomas Savery patented a design for a steam-driven pump. In 1712 Thomas Newcomen produced an internal combustion engine that used steam pressure.

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However, no internal combustion engine could provide a sustained power source until the 17th century, when steam engines became practical.

A steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth in a cylinder, which moves.

This movement can be used for rotary motion, such as that provided by an electric motor or turbine, or linear motion of an actuator arm. Steam engines have been used to provide mechanical power since the 18th century.

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In 1807, Richard Trevithick built and demonstrated his Puffing Devil road locomotive, believed by many to be the first demonstration of an internal combustion engine. The first internal combustion engine to be patented was by German inventor Nikolaus Otto in 1876. His 4-stroke cycle engine was a compression ignition engine, which means that fuel is ignited by the high pressure resulting from compressed fuel in the cylinder.

However, it wasn’t until 1885 that an automobile powered by an internal combustion engine became available for sale (the Benz Patent-Motorwagen).

The first engine of this type was used in a stationary power plant. Later, in 1892, French engineers Jules Gaston Mercier and Auguste Rateau fitted a double-acting 2-stroke Otto engine to the first automobile, a Peugeot Quadricycle.

This invention helped create a global demand for motor vehicles. However, it wasn’t until 1903 that an American, Charles Yale Knight, invented the first full-flow 4-stroke engine. He manufactured these engines under the name “Knight” and became very wealthy as a result (and also due to his brother inventing the spark plug). In 1905 Henry Ford built his first car with one of these engines, and it ran on gasoline.

Russian engineer Felix Wankel invented and patented a rotary engine with an eccentric shaft during WWI. This shaft drove three rotors; one rotated inside of another rotor that rotated inside of a third rotor.

Equation for Engine Working

Engines are characterized by their power, which measures their efficiency at converting the input energy into output motion. The equation describes this input-output relationship:

Power = Work/Time

Where work is measured in units of energy (ergs) and time in units of seconds.

An engine’s power is also measured at a specific RPM (revolutions per minute). The same engine will have different power ratings depending on the speed it’s turning at.

For example, an engine with a power rating of 50 hp turning at 3000 rpm will be doing less mechanical work than the same engine with a power rating of 50 hp riding at 1000 pm. The first example would be considered more powerful or capable than the second, even though they both have the same HP rating.

If you compare engines, be sure to compare them under the same conditions, i.e., with both engines turning at the same RPM.

Parts of Engine

There are many parts of an engine, so it is overwhelming to even think about how they work. Each engine’s components have a specific function, and they all work together to have a smoothly running car or boat.

There are many different types of engines, and the most common one is the internal combustion engine. The internal combustion engine has various parts that all work together for a smooth-running engine

There are numerous parts of an engine, and in this article, we look at the main ones:

Cylinder Block

The engine block is the large metal cylinder that holds all the other engine components in place. It also has a series of holes drilled through it to allow fuel and air to travel to the different parts of the engine.

The engine head is the top part of an engine block. It holds valves, sparks plug, and fuel injectors. The camshaft connects to it through a timing belt or chain.

The head is attached to one end of the engine block, and inside, it is where most of the components that make up an engine are located. It also contains the valves that work to control the flow of gases into, out of, and around various engine parts.

The cylinders are sealed within the engine block by a gasket. This means that when you have completed assembling your engine, there should be no visible gaps between the cylinders and other parts, such as the camshaft or crankshaft.

Cylinder Head

The cylinder head is the cover that holds the combustion chamber. The head is bolted to the top of the cylinder block. The combustion chamber is where fuel (gasoline or diesel) and air are mixed and ignited by the spark plug.

Directly behind the combustion chamber is a cooling system for the engine, consisting of a water pump, thermostat, and radiator.

Piston or Torak

The piston is housed in a cylinder and connected to a connecting rod. The connecting rod turns the crankshaft, which causes the pistons to move up and down inside their cylinders to produce power for your vehicle. The piston takes how much space inside the engine when it’s at its lowest point (called the “bottom dead center”). This measurement determines how an engine works, including its power output and efficiency. Engine displacement is measured in liters (1 liter = 1,000 cubic centimeters) or cubic inches (the size of a V8).

While moving up and down in its cylinder, each piston compresses a mixture of gasoline and air into the combustion chamber, where the spark plug ignites it. The force of this explosion pushes the piston back down, causing it to turn the crankshaft.

Engine knocking, also called pinging, or detonation, is a rapid popping sound that occurs when the fuel mixture in an internal combustion engine ignites prematurely. It is caused by a timing mismatch between the fuel-air combination and the spark plug firing.

Piston Rod or Connecting Rod

A piston rod attaches each piston to a crankshaft with a connecting rod. This allows the pistons to move up and down in their cylinders while providing structural support for each cylinder. This arrangement makes possible multi-cylinder engines like V8s, V6s, and straight-sixes.

Piston Rings

Piston rings are used to seal off a cylinder from the rest of an engine, so only gases from combustion can escape from it. Without these rings, you’d lose gas through any holes in your pistons or cylinder walls.


The crankshaft is the part of an engine that converts the up and down motion of the pistons into rotary motion. It’s connected to the flywheel and thus to the camshaft, which opens and closes the valves that let air into the engine and exhaust out.

A 4-stroke engine also opens and closes the intake valve several times during each revolution of the crankcase. A 2-stroke engine opens and closes the intake valve once per revolution.

The crankshaft looks like a bar with a long-tapered hole running through it. The taper is an essential feature because it allows more oversized bearings at both shaft ends.


The crankcase (or oil pan) contains the engine’s main bearings, which support the crankshaft. Each primary approach consists of a metal shell, a metal cap, and an inner sleeve hollowed out to allow oil to circulate the crankshaft. The hat is pressed tightly against the crankshaft end so that no oil can escape.

The inner sleeves are held in place by bolts that pass-through holes at the end of the sleeve. The outside of each bolt has a rubber seal to prevent oil from leaking out. If a bolt isn’t tightened enough, it might not fully sit against the inside of the inner sleeve. This allows engine oil to seep past the rubber seal and leak out.

An oily stain can identify a leaking crankcase on the floor underneath your car or truck. Other signs include smoke billowing from under the hood and unusually high engine noise. Engine gasket is the seal between the mating surfaces of an engine.

Working of Engine: How Does Engine Works?

The internal combustion engine works by burning fuel (like gasoline) inside the machine to create the force that pushes a piston back and forth. This action then causes wheels or propellers to spin.

The modern internal combustion engine uses a controlled fuel explosion to push a piston inside a cylinder. The piston is connected to the engine’s crankshaft via a connecting rod, and as the piston moves up and down, it rotates the crankshaft. This turns the wheels and drives the car along.

A typical two-stroke engine has three valves per cylinder: two intake valves (one for each cylinder) and one exhaust valve. Two lobes open the intake valves on an eccentric shaft, which is turned by a gear train driven by the crankshaft. The exhaust valve is opened by a lobe on another shaft, driven by gears from the crankshaft, which operates at half crankshaft speed in most engines.

In a four-stroke engine, there are four-piston strokes to complete a cycle: Intake, Compression, Power, and Exhaust. In a four-stroke engine, valves typically remain open longer during the exhaust cycle than they do during the intake or compression cycles. A typical arrangement is that every second stroke operates both an input and an exhaust valve, while every fourth stroke uses only an intake valve. This arrangement reduces pulsation because it allows alternating cylinders to share a single exhaust valve.

The parts of the engine and their working responsible for running the engine are listed below;


They produce energy by burning fuel inside a cylinder enclosed in a casing called an engine block. So long as there is air and fuel mixture in it, it keeps producing energy in the form of heat and sound until all its fuel gets exhausted, which is why internal combustion engines need fuel tanks to keep them running for a longer duration than any other engines which use external sources.


A piston is attached to a connecting rod and moves up and down inside a cylinder enabling it to 6. compress the fuel-air mixture


The valves allow fuel and air into the combustion chamber and exhaust gases out. Fuel injection systems are controlled by valves that open and close in response to signals from engine management systems. An engine valve controls the air-fuel mixture, which is then burned in the engine cylinder.


The crankshaft is located in the lower portion of an engine block. Connecting rods connect with the crankpins on the outer sides of the cylinder walls. The crankshaft converts linear motion into rotary motion to turn the wheels of a car.

Connecting rods

The Connecting Rods work to connect pistons to the crankshaft to move them up and down inside cylinders, enabling them to compress the fuel-air mixture inside them.

Spark plug or Fuel Injector

The spark plug is used in the petrol engine to ignite the compressed air-fuel mixture. While in a diesel engine a fuel injector is used to inject fuel on highly compressed air. In both cases combustion will happen inside the cylinder, piston reciprocates and power is transferred to the crankshaft from the piston.


The supercharger is connected directly to the engine block through an axle shaft. The amount of boost pressure can be controlled by either adjusting the position of an internal rotor or changing the number of rotors on the unit itself.

Types of Engine

There are many types of engines on various bases, all are discussed in detail below.

On the basis of Design

There are two internal combustion engines: reciprocating, turbo, and rotatory.

Rotary Engine

The cylinders move around a fixed crankshaft in a rotary engine rather than vice versa. This is to say that the crankshaft moves instead of the cylinders. The motion of the shaft is converted by pistons into a rotary motion at the ends of the cylinders so that the whole assembly rotates about an axis.

Turbo Engine

The turbocharger consists of a turbine and a compressor driven by exhaust gases from the engine. The exhaust gases leave the cylinder through an exhaust valve and pass into a hollow turbine wheel, which causes the compressor to compress air from the atmospheric intake into another concave turbine wheel, which drives the other compressor wheel.

The compressed air passes through an intercooler and enters the engine inlet manifold as a pressurized mixture with fuel already mixed in it. Thus boosted, it returns to its combustion chamber, where it burns with additional force and produces more power than it would do otherwise.

Reciprocating Engine

A reciprocating engine (also known as a piston engine) is an internal combustion engine (ICE) in which the piston completes a reciprocating motion. It is the most common type of engine and can be found in virtually all motor vehicles (cars, trucks, motorcycles, buses, boats, tractors, and so on).

On the basis of Fuel Used          

Petrol Engine

A petrol engine is a type of internal combustion engine in which the fuel is ignited by the high temperature of the air in the cylinder.

Types of petrol engines

  • 4-stroke petrol engines: They are the most common type of motor vehicle engines, in which air and fuel are mixed in the intake stroke and compressed in the compression stroke, then ignited by a spark plug, and the spent gases then exit in two exhaust strokes.
  • 2 -stroke petrol engine: they have fewer moving parts than 4-stroke gasoline engines and are more compact and powerful for their size. Most 2-stroke engines cannot be throttled. They are mainly used as a motorcycle or small engines.

Diesel Engine

Diesel engines work on the principle that fuel does not need to be ignited to burn; it only needs sufficient heat. This heat is supplied by burning a small amount of diesel fuel injected into hot air at the top of the cylinder by a fuel nozzle directly into the combustion chamber.

Thus, diesel engines do not require ignition systems such as spark plugs, although they usually have glow plugs for starting purposes. The fuel-air mixture burns at constant pressure when compressed, then expanded over several strokes.

Gas engines

It is an internal combustion engine that uses gas as fuel, most commonly propane or natural gas. These engines are comparatively new and have been invented only in 20 years. Gas engines are cleaner and better than petrol and diesel engines because there is no smoke emission when they work.

On the basis of Cycle of Operation

The cycle of operation is the sequence of events in which a process occurs. There are three main types of bikes:

Otto Cycle Engine

It is the most commonly used internal combustion engine found in automobiles and is distributed widely worldwide.

Diesel Cycle Engine

Diesel engines use the diesel cycle, which operates similarly to the Otto cycle but with crucial differences. The diesel engine uses heat from compression and combustion to continue the process.

Dual Cycle Engine or Semi-diesel cycle engine

This classification applies to internal combustion engines that use both Otto and Diesel cycles, such as gas turbines, etc.

On the basis of Number of Strokes

The number of strokes required for the combustion to be finished is the number of strokes in an engine. This is the main characteristic of the engine type. The following are the different types of engines:

Four-stroke combustion engine:

It is commonly known as the Otto or diesel cycle; this is a complete combustion process. All four strokes, i.e. intake, compression, power, and exhaust, occur in each revolution of a crankshaft.

Two-stroke combustion engine

Only intake and exhaust strokes occur during one revolution of a crankshaft in this engine type.

Hot spot ignition engine

This type of engine has no crankshaft, cylinders, or pistons, but it has a hot spot ignition system in which fuel is directly sprayed onto a scorching spot which ignites it and produces power.

On the basis of Ignition

Spark Ignition Engine

In a typical spark-ignition engine, the air-fuel mixture is drawn into the cylinder by the suction created by the downward motion of the piston. The fuel is then compressed by the piston and ignited by a spark plug.

Compression-Ignition Engine:

Compression ignition is a type of internal combustion in which heat from combustion is used to raise the air temperature within the cylinder to such a temperature that it ignites without requiring a separate ignition source.

On the basis of Numbers of Cylinders

Single Cylinder Engine

A piston moves up and down within a cylinder in a single-cylinder engine. The piston is connected to a crankshaft by either one or two connecting rods, which run along the bottom of the cylinder.

Single-cylinder engine power can be increased by increasing the size of the cylinder bore, the stroke length, and the number of cylinders (i.e., in a Vee form).  Single-cylinder engines have been mostly phased out for automotive use instead of multi-cylinder engines.

Double Cylinder Engine

Two pistons move up and down inside one cylinder block in a double-cylinder engine, also known as an inline engine. Thus, a four-stroke cycle engine has two combustion chambers and produces power every 180 degrees of crankshaft rotation.  The significant advantage of these engines is that they are simple and more compact than multi-cylinder engines

Multi-Cylinder Engines 

In multi-cylinder engines, two or more cylinders are arranged in one bank (or row), usually at an angle to each other. The angle between cylinders in an inline or straight engine is 180 degrees; in a V-type engine, it is 90 degrees.

On the basis of Arrangement of Cylinders

Horizontal Engine

In this type of engine, the cylinder block is located horizontally, and all the cylinders open out into a common crankcase. For example, Glasgow, Yarrow, and Sulzer marine engines are this type.

Vertical Engine

All the cylinders are mounted vertically and open out into a common crankcase in this type of engine. The R.E.P, Beardmore, Atlas, and Napier marine engines are this type.

Radial Engine

 In this engine type, all the cylinders are mounted radially at one end of the crankcase and open out into a common crankcase.

V-type engine

In this type, two rows of cylinders are arranged in a V configuration where one row is placed horizontally and the other vertically. This type includes V-6, V-8, V-10, and V-12 engines.

W-type engine

In this type, two rows of cylinders are arranged in a W configuration where both rows are placed horizontally, one after another. This type includes W-4 and W-6 engines.

Opposed cylinder engine

In this type, two rows of cylinders are arranged at opposite ends facing each other. In this case, one row is placed vertically and the other horizontally.

On the basis of Valve Arrangement

L-head engine

The L-head engine is the oldest type of internal combustion engine. This type of engine has more power than any other internal combustion engine. There are many advantages of L-head engines such as: –

Due to the air-cooling systems, there is no need for a complex water-cooling system within an internal combustion engine. Thus, an efficient cooling system can be designed to produce a high output of energy from a smaller amount of fuel.

F-Head Engine

The valves are on the side of the cylinders. Hence it is called I-head. Both inlet and outlet valves are present at one end of the cylinder walls opposite each other. All valves are arranged in a single plane, so it is called F-head. Both intake and exhaust valves are present at one end of the cylinder walls in this arrangement.

T-Head Engine

In this type of engine, there is one valve for every cylinder. The valve faces are on opposite sides and open and close together.

T-Head Engine

The T-head arrangement has all inlet and outlet valves arranged parallel. Hence it is called T-head. Ford Motor Company mostly used this arrangement for its V8 engines.

On the basis of Cooling

Air-cooled engines

They are also known as atmospheric engines. In this engine type, cooling is achieved by air circulation through the machine. The air intake takes in and then passes through the cylinders, where it gets heated. Then it is discharged from the engine with waste gases for cooling purposes.

Air-cooled engines work best under conditions of light loads and at low speeds. The advantages of these engines are that they have a high power-to-weight ratio, a simple design, and better accessibility for repair and maintenance purposes.

Water-cooled engines

In this engine type, cooling is achieved by circulating water through jackets fitted around the cylinders or cylinder block. Water may be taken indirectly from a separate water reservoir or from the same source as that of combustion steam, and the following points can be noted about these types of engines:

  • These engines are more complicated than the air-cooled ones because they involve complex mechanisms for pumping water.
  • Due to this complication, they are more expensive than the air-cooled ones.
  • Their performance decreases if the temperature increases beyond a specific limit and vice versa.

Maintenance of Engine

The engine is the heart of a car. It converts fuel into energy that powers the vehicle, but it also heats up and needs to be cooled down. And it’s one of the most critical parts of your car to keep in good shape.

  • The first step toward keeping your engine healthy is making sure you treat it well. Some people will tell you that the best way to do this is by following the manufacturer’s maintenance schedule, but this isn’t always true, so don’t feel guilty if you skip a few oil changes here and there.
  • You should change your oil every 3,000 miles or once every three months if you drive fewer than 10,000 miles per year.
  • If your vehicle is new or under warranty, follow the recommended service schedule — but if not, change your oil regularly (and check your oil level regularly while you’re at it).
  • You can also extend the life of your engine by changing the air filter once or twice a year and getting a tune-up once a year.
  • The user should check whether any warning lights are on in their dashboard. These are an indication of a potential problem.
  • The next step is to check the fluids in the car, such as antifreeze, oil, transmission fluid, and coolant.
  • It is necessary to get them checked at a garage to be topped up if required.
  • The tires should also be checked because a flat tire can cause serious problems and even cause accidents.
  • To make sure the tires are not worn out, the user should regularly use a tire gauge to know when it’s time for new tires.
  • There may be some loose nuts and bolts on the car that need tightening, too; it is essential to check them before every journey to avoid unwanted noises during travel.
  • It is also essential to keep up with regular vehicle maintenance checks and services as recommended by manufacturers to avoid car breakdowns, leading to traffic accidents and loss of money and time.

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The engine is one of the more essential concepts in machinery and machinery working. A machine can’t be adequately called until it has an engine. An engine is used in three-wheelers, passenger cars, trucks, etc. The size of the motor depends on the use of that engine. Engines like petrol and diesel engines are also available with enhancements to work in extreme conditions.

Moreover, its maintenance is essential to keep the car engine’s life. Some car owners ignore the proper care of the machine, and this practice will make your car burn out even earlier than expected. When used, the engine changes its status, e.g., installed new oil or filter. If a certain period does not change engine fluids, it will cause the engine to die early because of a lack of lubrication and cooling when it is running.

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