How a Car Engine Works

car engine showing pistons and crankshaft

The piston

The piston is the powerhouse of the car engine. The piston moves up and down. When the piston travels to the end of its range whether up or down, it is called a stroke.

A car engine is equipped with 4 or more pistons. The movement of these pistons is transferred to the wheels of the car which enables it to move.

For car engines, 4 strokes usually completes the engine circle enabling power to be transmitted to the wheels. 

exploded view of a car engine

The four stroke cycle, how it works.

First stroke; intake.

 The piston descends, sucking an air-fuel mixture into the cylinder .

The valves open allowing fuel – mixture into the cylinder

2nd stroke; compression

With all valves closed the piston comes back up,  compressing the fuel and air  mixture 

3rd stroke ; internal combustion

An electrical spark from the spark plug ignites the compressed fuel and air mixture inside the cylinder causing an internal combustion. The resulting combustion forces the piston to the bottom of the cylinder again.  A connecting rod transfers 

this power to the crankshaft which in turn transfers power to the wheels which enable the car to move.

4th stroke; exhaust. 

The piston comes back up,  pushing the burnt fuel and air  mixture out through the

open exhaust valves and the exhaust port.

The pistons and connecting systems

For smooth power delivery,  A car uses at least 4 pistons. These pistons take turns to fire the engine.

 Camshafts  are  specially shaped 

cams that  push spring-loaded valves open in turn.  

Cam gears and a timing belt or chain 

links everything to the crankshaft.  The crankshaft translates piston power from the engine to the wheels.  

It has counterweights to balance against the 

pistons for perfectly smooth revolutions.

The engine block holds the crankshaft 

and cylinders, and the cylinder  head holds valves, ports, cams, etc.

A geared flywheel sits at one side of the  

crankshaft for connection to a transmission.

The basic car engine has four cylinders 

arranged in a single row.  But there are many other possible configurations, including six, eight and 12 cylinders.

 Systems that support the internal  combustion process.

Air intake system

Air comes in through an air filter,  and then into the intake manifold where it mixes with fuel before being sucked  into individual cylinders through intake ports.

Fuel injection system

The fuel pump carries gas from the tank,  through a fuel filter, to the engine 

where fuel injectors emit a precisely 

timed spray of gas into the intake port.

Cooling system

Engines get very hot during operation  and 

require a cooling system. The cooling system  basically consists of a radiator, water pump and cooling channels. Cool water from the radiator is pumped through cooling channels that go around the hot cylinder blocks, cooling the engine in the process. This hot water then passes through the radiator and is cool again for recirculation.

The radiator has a network of small tubes and fins. As hot water passes through these tubes it is cooled with the aid of fins and radiator fans.

Electrical system

This is a complex system that basically consists of the battery, fuses, wiring , coils, spark plugs, and the alternator.

The battery provides the initial electrical connection that enables the car to start. The alternator is like an electric generator. Once the car engine starts running, the alternator basically charges the battery and generates the electricity required for the whole car to function properly

 lubricating system

Just like the cooling system, the engine lubricating system basically consists of , engine oil, oil storage,  oil lubricating channels, oil filter and oil pump.

The oil pump keeps oil properly 

pressurized and flowing.

It pumps the motor oil  to lubricate, cool,  clean, prevent corrosion of the engine.

The oil filter keeps oil clean from contaminants.

Exhaust system

The exhaust manifold collects gases 

from multiple cylinders into one pipe. 

Exhaust flows through the catalytic converter, which captures toxic chemicals in engine exhaust. And then out through a muffler that reduces exhaust noise.

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