Understanding Your Car’s Engine: A Guide to 4-Cylinder Petrol Engine Parts

The unassuming saloon car you drive every day holds a marvel of modern engineering under its hood: the 4-cylinder petrol engine. Let’s delve into the key parts that make this engine tick and propel you down the road.

1. The Powerhouse: Engine Block and Pistons

Car Engine Internals

Imagine a metal box – that’s the engine block, the foundation of the engine. Inside, four cylindrical chambers called cylinders are carved out. These are the pistons’ playgrounds. The pistons, like tireless metal athletes, constantly move up and down within the cylinders, creating the power that drives the car.

2. The Breath of Life: Intake Manifold and Valves

intake manifold

Just like us, the engine needs air to “breathe” and function. Air enters through the intake manifold pipe that channels fresh air into the cylinders. Tiny valves, like controlled gates, open and close at precise moments to let the air in and out of the cylinders.

3. The Spark of Genius: Spark Plugs and Ignition System

Removing a spark plug

Air is crucial, but it needs a spark to ignite. That’s where the spark plugs come in. These screw into the cylinder head, the top part of the engine block. The ignition system sends a high-voltage jolt through the spark plugs, creating a spark that ignites the air-fuel mixture inside the cylinder.

4. The Fuel Delivery System: Fuel Tank, Injector, and Fuel Pump

Petrol, the car’s drink of choice, is stored in the fuel tank. A fuel pump acts like a heart, pushing petrol through a network of pipes. Finally, the fuel injector, a precise nozzle, sprays a measured amount of petrol into each cylinder for combustion.

5. The Power Transfer: Connecting Rods and Crankshaft

Piston Crankshaft assembly

The pistons’ up-and-down motion needs to be converted into rotational motion to drive the wheels. Here’s where the connecting rods step in. These metal rods connect the pistons to the crankshaft, a long, rotating shaft that sits inside the engine block. As the pistons move, the connecting rods push and pullthe crankshaft, causing it to spin.

6. Exhausting the Process: Exhaust Manifold and Catalytic Converter

Car Exhaust System

Combustion creates exhaust fumes. The exhaust manifold collects these fumes from each cylinder and channels them out of the engine. But before they exit the car, they pass through a catalytic converter, a metal honeycomb-like structure that converts harmful pollutants into less toxic gases, making your car more environmentally friendly.

7. Keeping it Cool: Cooling System

Car engine Cooling System

All this activity generates heat, and just like us, the engine needs to stay cool. The cooling system, consisting of a radiator, coolant, and water pump, circulates coolant throughout the engine, absorbing heat and carrying it away to the radiator, where it dissipates into the air.

8. The Brain Behind the Brawn: Engine Control Unit (ECU)


The ECU acts as the engine’s conductor, constantly monitoring and regulating various aspects like fuel injection, spark timing, and engine temperature. Sensor data from throughout the engine is fed to the ECU, which then adjusts engine operation for optimal performance and efficiency.

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