Internal Combustion Engines: Types, Working Applications

Internal Combustion Engines or in short IC Engines finds their application in cars and bikes. Study of Engines belongs to the branch of Mechanical Engineering.

There are two types of IC Engines:

  • 4-Stroke-Engine

  • Two Stroke Engine

The engines can also be classified on the cycles which they follow:

  • Diesel Engine

  • Gasoline Engine

Four stroke engines have four different cycles:

  • Intake

  • Compression

  • Ignition/expansion

  • Exhaust

In the two strokes, there are two cycles and each that runs at the same time.

  • Intake/exhaust

  • Ignition/compression


TDC: Top Dead Centre. The top part piston which reaches in a vertical engine.

BDC: Bottom Dead Centre. This is the bottom part that reaches in a vertical engine.

Compression Ratio: It says how much the engine compresses a certain volume of air that it intakes. A compression ratio of 14:1 indicates that for every 14 unit volume of air which is taken in, the piston compresses that air to 1 unit volume.

One of the factors that reduce the compression ratio is an explosion where instead of burning in a controlled method, the air/fuel mixture explodes and damages the engine.

Compression Ratio= (Swept volume + Clearance volume)/Clearance volume

Swept volume= Volume of piston traversed as it completes one full stroke from the TDC to BDC

Clearance volume= Volume of the combustion chamber

Petrol Engine

Also called Spark Ignition engines, requires ignition from an external source for the engine to begin.


Reciprocating engines can be classified in several ways. Some are mentioned below:

1. Based on how they are cooled

a. Air-cooled Engines

b. Water-cooled Engines

2. According to a number of strokes

a. 2-stroke engines

b. 4-stroke engines

3. Based on Cylinder arrangement,

a. Inline cylinder arrangement

b. V-cylinder engine or V-engine

4. According to the way valve is arranged:

a. Single overhead camshaft (SOHC)

b. Double overhead camshaft (DOHC)

Parts of a Petrol Engine:

1. Cylinders

2. Cylinder block

3. Piston and Connecting rods

4. Cylinder head Crankcase

5. Valves

6. Crankshaft Flywheel

7. Exhaust system

8. Camshaft Fuel system

9. Lubrication system

10.Ignition system


When a piston goes to the top of the cylinder, the sparking plug fires. The spark powers the air-fuel mixture that cause a mini explosion. No sooner, the fuel burns, giving off hot gas that pushes the piston back down. The fuel releases energy which powers the crankshaft.


These engines are used in vehicles, portable power plants, and other farm machinery.

Future Scope: There are ongoing researches to carry out an increase in fuel efficiency, lower the pollutants and make it lighter and closely packed.

Diesel engine

This is an internal combustion engine which transforms chemical energy of the fuel to mechanical energy and causes reciprocating motion inside the cylinders.

Types of Diesel Engines

Diesel engines can be four-stroke or two-stroke.

Four-Stoke Diesel Engine

A four-stroke engine is an internal combustion engine wherein the piston finishes four separate strokes to complete single thermodynamic cycle. A stroke means piston along travels completely along the cylinder, in both directions.

Two-Stroke Diesel

The cylinder top has two or four exhaust valves which open simultaneously. The piston elongates, as in a gasoline two-stroke engine, to behave as an intake valve.

With this, we conclude. Hope this piece of information helps.

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