Main parts of an IC Engine with Explanation

Today I am going to explain the main parts of an IC Engine.

If you are looking to know about the same, then you landed in the right place and this will be your final stop, I guess.

So, come with me and join the journey of this knowledgeable journey along with Engineers Rail.

Before I take you to the mainstream of this session, Here is a gift for you-

You can download this whole article as an internal combustion engine parts and functions pdf and internal combustion engine parts and functions ppt. Don’t forget to grab your freebies at the end of the article.

So, Le’s dive into the mainstream of the article and allow me first start with some basics.

Here we go…

What is IC Engine?

Internal Combustion(IC) Engines are those in which combustion takes place inside the engine. The heat generated due to combustion is used directly to exert pressure on the piston.

Every vehicle you can see on the road comes under the IC engines, where fuel burns inside the cylinder. For example, petrol engine or diesel engine.

To know more about IC engines, you can check out the Classification of Engines


An internal combustion engine is a device that converts reciprocating or linear motion into rotary motion by burning fuel.

Two types of IC Engine or classification of IC engine are seen nowadays-  

  • Petrol engine or spark-ignition engine
  • Diesel engine or compressor ignition engine

Now, let’s jump to the study of the different components of IC engine and its functions with diagram

Parts of IC Engine and its function-

Here are the Different components of IC engine

  • Cylinder
  • Cylinder Head
  • Piston and Piston rings
  • Piston pin OR gudgeon pin
  • Connecting rod
  • Crank and Crankshaft
  • Engine Bearings
  • Crankcase
  • Flywheel,
  • Valve and valve Mechanism
  • Spark Plug
  • Carburetor
  • Fuel Injector


It is the heart of the engine in which fuel is burnt and the power is developed.

A cylinder of an IC engine has to withstand very high pressure and temperature because the combustion of fuel is carried out within the cylinder.

Therefore, the cylinder must be cooled. It may be air-cooled in the case of low-capacity engines like two-wheelers or water-cooled in case of high-capacity engines like cars, trucks, etc.

To avoid the wearing of the cylinder block, a sleeve will be fitted tightly in the cylinder. Materials used for the cylinder are high-grade cast iron or alloy steel.

It may also use aluminum alloys where weight is considered in the case of airplanes and automobiles.

cyclinder of ic engine

Cylinder Head-

Another parts of an IC engine, the function of the cylinder head is to seal the top end of the cylinder. It provides space for the valve mechanism, spark plug, fuel injector, etc.

It is made of cast iron or aluminium.

cylinder head of ic engine


Piston and Piston Rings-

The function of the piston is to transmit the gas force to the connecting rod, hence, to the crank.

It slides in the cylinder. Usually, the piston is made of cast steel and aluminium alloy because it requires strength.

Pistons are hollow inside due to one face of the cylinder being worked to reduce the weight of the piston.

Piston rings made of cast steel are provided to prevent the leakage of gas into the crankcase. Upper rings are called compression rings.

Lower piston rings are oiling rings. These rings have an oil groove with several holes to discharge the excess lubricating oil from cylinder walls to drainage holes in the piston from where oil is sent back to the oil sump.


Gudgeon Pin or Piston Pin-

It is the pin joining the small end of the connecting rod and piston. It is made of hardened steel by the forging process.

piston pin

Connecting Rod-

One end of the connecting rod is connected to the Piston through a gudgeon pin called a small end and another end to the crank through a crankpin called a big end.

The connecting rod transmits the piston load(gas force) to the crank. It converts the reciprocating motion of the piston into the rotary motion of the crankshaft.

These are basically made of nickel, chrome, and vanadium steels by the forging process.connecting rod

Crank and Crankshaft-

The crank is an integral part of the crankshaft. It rotates about the axis of the crankshaft and causes the connecting rod to oscillate.

It also carries the flywheel to even out the fluctuating torque. The crank and crankshaft are steel forged and machined to a smooth finish.


Engine Bearing-

The crankshaft is supported by main bearings, which are lubricated. The function of bearings is to facilitate smooth motion to the crankshaft and reduce friction between them.

engine bearing


The crank, crankshaft, and main bearings are set in the crankcase. The bottom of the engine is closed using an oil sump, which carries lubricating oil.



A heavy rotating mass is attached to the crankshaft outside the crankcase called a flywheel.

It minimizes cyclic variation in speed by storing the energy during the power stroke and the same is released during other strokes. It is made of steel or cast-iron discs.


Valve and Valve mechanism-

The engine has two valves, namely, the suction valve and the exhaust valve. These valves are operated by a cam mounted on a camshaft.

The camshaft rotates at half the speed of the crankshaft, in the case of four-stroke engines with the help of timing gears having a tooth ratio of 1:2.

Spark Plug-

The function of a spark plug is to provide a high-intensity spark for the combustion of fuel and air in the cylinder in spark-ignition engines.

spark plug


The function of the carburetor is to prepare the mixture of fuel and air and meter it before sending it to the induction system of the engine according to the operating conditions of the engine in the case of spark-ignition engines.


Fuel injection Pump-

The function of the fuel pump is to inject the fuel into the cylinder under very high pressure in the case of compression ignition engines.



Here is the video guide to help you further, give a watch-



This is for IC engine components and functions. I hope you learned something today and this session added some value to you.

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Before you go, Here are your freebies all yours-

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Before you go, here are some questions and its answer regarding ic engine, have a look-


What is the meaning of cc in engines or automobile vehicles?

The cc means combustion volume inside the cylinder in a centimetre cube(cc).

what type of combustion method is used in an open cycle gas turbine?

Internal combustion.

Why efficiency of gas turbines is lower compared to ic engines?

In gas turbines, 70% of the output of the gas turbines is consumed by compressors. IC engines have much lower auxiliary consumption. Further combustion temperature of ic engines is much higher compared to the gas turbine.

In some engines, glycerin is used in place of water for cooling the engine. Why?

Glycerin has a boiling point of 90°C which increases its heat carrying capacity. Thus, the weight of the coolant gets reduced and a smaller radiator can be used.

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