I am a student of electrical engineering university of Ilorin, and this how an engine works. Let’s start at a single piston, the powerhouse of the engine and work our way outwards. The four-stroke cycle when a piston travels to the end of a range, whether up or down that’s a stroke. Car engines uses a four-stroke cycle, and it goes like this.

First intake. The piston descends, sucking an air-fuel mixture into the cylinder, through the intake port, with both intake valves open. Next, compression with all the valves closed the piston comes back up compressing the fuel and air mixture for more powerful combustion. Then, the power stroke, an electrical spark ignites the compressed fuel and air mixture and the resulting combustion forces the piston to the end of the cylinder again. A connecting rod transfers this power to the crankshaft. Finally exhaust, the piston comes back up pushing the mixture out through open exhaust valves and the exhaust port. Connecting multiple pistons for smooth power delivery, piston take turns firing. The firing order of this engine is 1-3-4-2. Camshafts with specially shaped cams pushing spring-loaded valves open in turn.


Cam gears and a timing belt or chain links everything to the crankshaft, and it all spins together. The crankshaft translates piston power out of the engine. It has counter weights to balance against the pistons for perfectly smooth revolution. This is what RPM means we are counting the number of full crankshaft revolutions per minute. The engine blocks hold the crankshaft and cylinders, and the cylinder head holds valves, ports, cam etc. A geared flywheel sits at one side of the crankshaft for connection to a transmission. Its also where a starter connects to the system.


This engine has four cylinders arranged in a single row. But there are many other possible configurations like six cylinders with three on each side, angled in a V-shape (known as v6 engine) or eight. Despite different design goals the basic engine parts are all there. Now let’s look at other systems that supports the combustion process.

Air intake air comes through the air filter, and then into the intake manifold where it mixes with fuel before been sucked into individual cylinders through intake ports. Fuel, the fuel pump carries gas from the tank through a fuel filter to the engine. Where fuel injectors emit precisely timed spray of gas into the intake port. Cooling, engines get very hot during operation and require a cooling system. Coolants channels around the cylinders and through the cylinders head and carries a special liquid called ‘’ Anti-freeze’’ to keep temperatures between safe operating range. It’s called anti-freeze because it won’t freeze in icy weather. After cooling hot engines parts, coolants circulate through the radiator. The radiator has a network of small tubes and fins. Coolants passes through this channel while air (pulled I by the radiator fan) flows by the tube, cooling the hot liquid for recirculation. A water pumps keeps the coolants system following and properly pressurized. The thermostat regulates coolants temperature by either routing coolants back through the engine or to the radiator for further cooling.


Electrical, the spark plug delivers the electrical spark that ignites the fuel-air mixture for combustion. Metal core is insulated from the outer metal causing with porcelain. The sparks jump between these conductive surfaces. The coil pack delivers electrical currents to the spark plugs as directed by the ECM (Engine control module) The ECM is a computer that directs many core engine functions like spark timing, valve timing, air to fuel ratio etc. The alternator works like a power generator, converting the engines mechanical energy into electricity to charge the battery or run other electrical systems while the engine is running. The battery provides power to the starter for engine start. Oil, motor oil is used to lubricate, clean prevents corrosion, improve sealing and cool the engine by carrying heat away from moving parts. Rings around the top of the piston head keep oil out of the combustion process while otherwise allowing the cylinder to be lubricated. Oil galleries are channels through the engine blocks and cylinder head that carry oil to various parts. Oil flows through the engine and back to the oil pan for recirculation. The oil pump keeps oil properly pressurized and flowing. Oil rests in the oil pan when not in circulation. The oil filter keeps oil clean from contaminants. Exhaust, 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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