What Is an Engine? | Types of Engine | Parts of Engine

All About Engine

What Is an Engine?

What Is an Engine?

Otherwise, consume fuels to performs mechanical works by exerting torques or linear force (usually in the form of thrust).

Devices that convert heat energy to speed are usually referred to as engines only. Examples of engines that exert a torque include the familiar automobile gasoline and diesel engines, as well as turboshafts.

Examples of thrust-generating engines include turbofans and rockets.

From reading the rest of that page, it seems that the term originally refers to any mechanical device that looks at any form of energy & converted it into useful mechanical motions.

So something connected to an air or water mill, or even powered by humans or animals, would be called an engine.

It is interesting to me that the meaning of the term has changed, and it underscores the dramatic significance of the invention.

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Types of Engine:

Types of Engine

When considering how many types of engine there are, engines can be broadly categorized into two types: external combustion engines and internal combustion engines.

  • External combustion engine:- In externals combustion engines, the combustion of fuel takes place outside the engines—for example, the steam engine.
  • Internal combustion engines:- In internal combustion engines, the combustion of fuels takes place insides the engine. Two-stroke and four-stroke petrol & diesel engine are examples of an internal combustion engine.

There are different types of engines, especially within internal combustion (I.C.) engines, and their classification of engines depends on various criteria.

Depending on the cycle of Operation, the types of engines are:

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1. The cycle of Operation

When asking which type of engine operates on the Otto cycle, the answer is Otto Bicycle Engines:-

These types of engines work on the Otto bicycle.

Diesel Cycle Engine:-

The engine working on a diesel bicycle is called a diesel bicycle engine.

Dual Bicycle Engine:-

The engine which works on both diesel, as well as Otto Bicycle is called Dual Bicycle Engine or Semi Diesel Bicycle Engine.

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2. Type of Ignition

Spark-ignition engine:-

In a spark-ignition engine, there is a spark plug that is mounted on the engine head. The spark plug produces a spark after compression of the fuel and ignites the air-fuel mixture for combustion. Petrol engines are spark-ignition engines.

Compression-Ignition Engine:-

In a compression ignition engine, there is no spark plug on the cylinder head. The fuels are ignited by the heat of compressed air. Diesel engines are compression ignition engines.

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3. Arrangement of Cylinders

One of the types of automobile engines based on cylinder arrangement is the Vertical Engine:-

In a vertical engine, the cylinder is arranged in a vertical position, as shown in the figure.

Horizontal Engine:-

In a horizontal engine, cylinders are placed in a horizontal position, as shown in the figure below.

Radial Engine:-

A radial engine is a reciprocating type of internal combustion engine configuration in which the cylinders protrude outward from a central crankcase like wheel spokes. When viewed from the front, it looks like a stylized star and is called a ‘star’ engine. It is commonly used for aircraft engines before the gas turbine engine does not prevail.


In a V-type engine, cylinders are placed in two banks with some angle between them. To prevent vibration and balance problems, the angle between the two banks is being kept as small as possible.

W Type Engine:-

In W type engines, cylinders are arranged in three rows in such a way that it forms the W type arrangement. The W-type engine is formed when 12 cylinders and 16 cylinder engines are made.

Reverse Cylinder Engine:-

In a reverse cylinder engine, cylinders are placed opposite each other. Pistons and connecting rods show similar speeds. It runs smoothly and has more balance—the size of the anti-cylinder engine increases due to its arrangement.

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4. Types of Cooling

When exploring what are the types of engines based on cooling methods, one common type is the Air-Cooled Engines:-

In air-cooled engines, the cylinder barrel is disassembled, and metal fins are used that provide a radiation surface area that increases cooling. Air-cooled engines are commonly used in motorcycles and scooters.

Water-Cooled Engine:-

In water-cooled engines, water is used to cool the engine. Water-cooled engines are used in cars, buses, trucks and other four-wheel vehicles, heavy-duty motor vehicles.

An anti-freezing agent is added to the water to prevent it from freezing in cold weather. Each water-cooled engine has a radiator to cool the hot water from the engine.

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5. Valve Arrangement

According to the valve arrangement of inlet and exhaust valves in different positions in the cylinder head or block, automobile engines are classified into four categories. These arrangements are named ‘L,’ ‘I,’ ‘F,’ and ‘T.’ It is easy to remember the word ‘LIFT’ to memorize the four-valve arrangement.

L-Head Engine:-

In these types of engines, the inlet and exhaust valves are arranged together and operated by a camshaft. The cylinder and combustion chamber form an inverted L.

I-Head Engine:-

In the I-head engine, the inlet and exhaust valves are located in the cylinder head. A single valve activates all valves. These types of engines are mostly used in automobiles.

F-Head Engine:-

It is a combination of an i-head and an F-head engine. A valve is usually in the inlet valve head, and the exhaust valve is in the cylinder block. Both sets of valves are operated by the same camshaft.

T-Head Engine:-

In a T-head engine, the inlet valve is located on one side, and the exhaust valve is on the other side of the cylinders. Here two camshaft is required to operate, one for the inlet valves and the other for the exhaust valve.

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6. Types of Design

Reciprocating Engine:-

In a reciprocating engine, there is a piston and cylinder, the piston moves (to and fro) within the cylinder. Due to the reciprocating motions of the pistons, it is called a reciprocating engine. 2 stroke and four-stroke engines are common examples of reciprocating engines.

Rotary Engine:-

In a rotary engine, the rotor performs a rotary motion to produce electricity. There is no reciprocal motion. A rotor is present in the chambers, which performs rotational motion inside a chamber. Wankel rotary engines, turbine engines are rotary type engines.

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7. Number of Strokes

Four-Stroke Engine:-

This is an engine in which the piston moves four times, i.e., two upwards (from form BDC to TDC) and two downwards (from TDC to BDC) in a cycle of the power stroke; it is four-stroke. It is called the engine.

Two-Stroke Engine:-

The engine in which the piston accelerates twice, i.e., one from TDC to BDC and the other from BDC to TDC to produce a power stroke, is called a two-stroke engine.

Hot Spot Ignition Engine:-

These types of engines are not in practical use.

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8. Types of Fuel Used

Petrol Engine:-

The engine which uses petrol to do its work is called a petrol engine.

Diesel Engine:-

The engine which uses diesel to do its work is called a diesel engine.

Gas Engine:-

The engine that uses gas fuel to work is called a gas engine.

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Parts of Engine:

Parts of Engine

When understanding what is engine and types of engine, it’s essential to note that automobile engines are complex mechanisms made up of many internal parts that act like clockwork to produce the power that drives your vehicle.

For the engine to operate properly, all of its parts must be in good condition. One mistake can be disastrous. Let’s take a look at the main part of the engines.

Engine Block:-

The blocks are the main part of the engines. All others parts of the motor are essentially attached to it. Inside the blocks is where the magic happens, such as combustion.


As the spark plug fires, the piston pumps up and down, and the piston compresses the air/fuel mixture.

These reciprocating energies are converted to rotary motion & transferred by the transmission, through the driveshaft, to the tires to spin them.

Cylinder Head:-

The cylinder heads are attached to the top of the block to seal the area to prevent loss of gases. It consists of spark plugs, valves, and other parts.


Located near the bottoms of the engine block, it is the part that converts energy from reciprocating to rotary.


The camshaft opens and closes the valve at the right time along with the rest.


Valves control the flow of air, fuel, & exhaust fumes inside the cylinder head. There are both intake valves & exhaust valves.

Oil Pan:-

The oil pan, also knowns as oil sumps, attaches to the underside of the engine & stores all the oils used in the lubrication of the engine.

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Frequently Asked Questions (FAQ)

Types of Engine

Types of engines and how they work

Thermal engines. Internal combustion engines (IC engines) External combustion engines (EC engines) Reaction engines.
Electrical engines.
Physical engines.

What Is an Engine?

An engine is a machine designed to convert one or more forms of energy into mechanical energy. Mechanical heat engines convert heat into work via various thermodynamic processes. Engines – such as the ones used to run vehicles – can run on a variety of different fuels, most notably gasoline and diesel in the case of cars.

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