Basic Components of IC Engine and Their Function

ic engine components

Even though there are different type of internal combustion engine and each engine has hundreds of components, there are some basic components that are present in almost all engine. Those who are study IC engines should know this basic component, and often used terminology in IC engine.
Figure shows the cross section of an SI engine, various components and its function is described below.

🔗Difference between SI Engine and CI Engine
🔗Comparison between two stroke and four stroke engine

Cylinder block
BMW 6 cylinder block Al-Mg
BMW 6-cylinder block

Cylinder block is the main body of engine. This is the main supporting structure which holds the other components together and provides mounting points. Cylinder block is manufactured by casting. The material used may be iron or aluminium. For a multi cylinder engine, cylinder block is cast as a single unit. The cylinder head is tightly mounted on the top of cylinder block with bolt and studs. These two parts are provided with an appropriate cooling system (water jacket, cooling fins). Cylinder gasket is used to seal all mating surfaces including between cylinder head and cylinder block. The material of the gasket may be rubber, paper, cork, or metal. The bottom portion of cylinder block is known as crankcase.

Cylinder is a space or cylindrical vessel supported by the cylinder block, in which the piston makes reciprocating motion. During the operation of engine, the volume inside the cylinder is filled with working fluid and subjected to different thermodynamic process.

engine cylinder piston

Piston is a tubular component that fitted into engine cylinder. Its motion is restricted to one dimension, it makes reciprocation movement inside the cylinder. Piston ring s and lubricants provided to make the fit is gas tight. It also acts as a link in transmitting gas forces to rotary motion of output shaft.

Piston rings
engine piston rings

Piston rings are provided on the piston to provide a gas tight seal between piston and cylinder wall. This is fitted into slots on the outside diameter of the piston to prevent leakage of combustion gas during engine running.

Combustion chamber
Combustion chamber is the space enclosed between the cylinder and the piston top during the combustion process. The combustion of fuel, and releasing thermal energy and building up of pressure occur at the combustion chamber.

Connecting rods
engine connecting rod

It is a metal rod which connects the piston and the crankshaft. It transmits the power on piston to the crankshaft. The small end of connecting rod connected the piston by gudgeon pin and the big end of it connected to the crankshaft using crankpin.


Crankshaft is a component which enclosed in the crankcase and converts the reciprocation motion of piston to the rotary motion of output shaft. Bearings are used to support the crack shaft, reduce friction and allows it to freely rotate under various load conditions. The pair of crank arms and balancing weights are provided on them for static and dynamic balancing of the rotating system.

Spark plug

It is the component of spark ignition engine to initiate the combustion process. It is usually located at cylinder head.

The engine seals are located at the end of shaft that goes to the outside the cylinder block. Seals protect the bearing and preventing gas as well as oil leakage.

Cams and Camshaft
Cams and camshaft are the parts of engine which controls the opening and closing of inlet and exhaust valves. Cam and camshaft are driven by crankshaft by using timing gears and they are designed to in such a way that it opens the valves at correct timing and keep it open for the necessary duration. The camshafts are also used to drive the ignition system.

Inlet and exhaust valves
They are the valves provided in the cylinder head to regulate the flow of working fluid into the cylinder and expelling of combustion products to the atmosphere.

Inlet manifold and Exhaust manifold
The pipes which connect the inlet system to the inlet valve is known as the inlet manifold. The air, air-fuel mixture are drawn into cylinder through inlet manifold.

Exhaust manifold is the pipe which connects exhaust system to the exhaust valves. The products of combustion like CO, NOx etc... escape into atmosphere through exhaust manifold.


Read: What is flywheel? function, applications and equation for energy stored

The torque on the crankshaft fluctuates during the one cycle of combustion, and cause fluctuation of angular velocity of the shaft. Flywheel is an inertia mass attached to the output shaft to minimize this fluctuation and achieve the uniform torque.

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