Gasoline engine: structure, principle of operation, advantages and disadvantages

Gasoline engine – a special type of piston ICE (internal combustion engine), in which the ignition of the TS (mixture of fuel and air) in the cylinders is forced by an electric spark, and gasoline is used as fuel. If your car’s engine and other major parts are out of commission because of an accident, recycle your car. Get a lot of money and you can buy a new car: https://towingandscrapcarremoval.ca/scrap-car-removal-thornhill.

Types of gasoline engines

Modern gasoline engines can be classified into several categories.

According to the number of cylinders – with one cylinder, two cylinders and several cylinders.

According to the arrangement of cylinders:

In-line engines (cylinders arranged strictly in a row in an inclined or vertical manner);

V-shaped engines (cylinders arranged at an angle);

W-shaped engines (cylinders arranged in four rows at an angle with the crankshaft)

opposed engines (cylinders arranged at 180 degrees)

by the way of obtaining a fuel mixture – injector, carburetor.

By type of lubrication – separate (oil is only in the crankcase), mixed (oil is mixed with fuel).

By cooling method – liquid cooling, air cooling.

According to the type of cycles – two-stroke, four-stroke.

According to the type of air mixture supply into the cylinders – with a supercharger, without a supercharger.

The principle of operation of the gasoline engine

The operation of the gasoline engine, as well as any other internal combustion engine consists in the combustion of the fuel mixture in a closed space, in this case, in the combustion chamber. During combustion, a large amount of thermal energy is released, which triggers the mechanical operation of the main engine mechanism. 

To ensure continuous mechanical operation of the internal combustion engine, a continuous (cyclic) supply of fuel to the combustion chamber must be carried out.

In most cases, gasoline engines are four-stroke engines, whose duty cycle consists of four cycles:





More about each of the four cycles.


Piston motion begins at one point (lower or upper), with the intake valve opening and fuel being fed into the combustion chamber. After the piston stops at the opposite extreme point, all intake valves close.


During this stroke, the piston returns to its starting point, compressing the incoming fuel mixture, increasing its heating temperature. After the piston reaches the extreme point, the compressed fuel mixture is ignited by the spark plug.

Working stroke

During combustion, the fuel mixture forms gases, the expansion of which pushes the piston out. All valves remain completely closed during the stroke.


While the crankshaft continues to rotate, the piston moves to the upper endpoint. Along with it, the exhaust valve opens, with the piston pushing the gases into the gas distribution system. When the stroke is complete, all exhaust valves close.

The whole working process is cyclic, so after completion of one stroke, the next stroke begins.

Main elements of gasoline engine


The main working element of the internal combustion engine is the piston, connected to the crankshaft by a special connecting rod. This forms the crank and connecting rod mechanism, which converts the reciprocating movement of the pistons into a working stroke (rotation) of the crankshaft.

To ensure proper compression in the engine cylinders, the piston is fitted with sealing cast-iron rings. Modern gasoline engines can be fitted with narrow (no more than 2 mm high) and wide piston rings (up to 3 mm high).

Connecting rod

Connecting the piston and crankshaft. Connecting rods are made from heavy-duty steel, and less commonly, aluminum. Operating crank rods are always double-acting.


The reciprocating piston movements are converted into rotary movements of the shaft, which is responsible for turning the car wheels.


The internal combustion engine is equipped with special valves – inlet and outlet valves. They are designed to inlet the air mass and outlet the exhaust gases obtained in the process of combustion of fuel.

Spark plug

Gasoline engines are equipped with spark plugs to ensure the ignition process of the vehicle in the chamber. An electric spark plug ignites the TC at a specific point in its feed and piston passage.

Auxiliary operating systems of the gasoline engine

Uninterrupted and efficient operation of the gasoline engine is ensured by auxiliary working systems – starting the engine, ignition, fuel-air mixture, cooling, exhaust outlet, lubrication.

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