What goes on in the engine?

My car has a six-litre, V12 engine. Like real.

The car that I actually drive is much smaller, but my point here is whether the jargon like "V12", "spark plug", "intake valve" and the like make sense to the layman, and whether most drivers really know what's going on under the hood.

If you're feeling totally lost at this point, welcome to the club. But fret not. Let's go through a quick overview of how engineers work, and you'll have a clearer picture at the end.

The basics

The main purpose of an engine is to convert the latent energy in fuel (such as petrol or diesel) into kinetic energy which propels your car. Based on current technology, the best way to translate fuel into motion is to burn it within the confines of an engine. A car engine is therefore an internal combustion engine.

The underlying idea is: if you put a small amount of high-energy fuel in a small, enclosed space and ignite it, a great amount of energy is released in the form of rapidly expanding gas (or an explosion, in other words). And you can use the energy created by the explosion to move your vehicle.

This is what happens inside the cylinder of an engine, so let's proceed to take a more detailed look at this compartment.

The cylinder

The cylinder is the core of your car engine. It is a rather complex contraption consisting of a piston, valves, spark plug, crankshaft and other parts. In very simple terms, fuel goes into the cylinder, gets ignited, and the resulting explosion propels mechanical parts which eventually translate the energy into rotational motion.

Most cars nowadays use what is called a four-stroke internal combustion cycle consisting of an intake stroke, compression stroke, combustion stroke and exhaust stroke. How the cycle works is as follows:

1. Intake stroke

• At the beginning of the cycle, the piston is near the top of the cylinder.
• When the intake valve opens, the piston moves down to let air and fuel flow into the cylinder.

2. Compression stroke

• The piston moves up again to compress this fuel-air mixture. Compression makes the subsequent explosion more powerful.

3. Combustion stroke

• Once the piston reaches the top of its stroke, the spark plug emits a spark to ignite the fuel-air combination.
• An explosion then occurs, which forcefully drive the piston downwards.

4. Exhaust stroke

• Once the piston hits the bottom of its stroke, the exhaust valve opens and the exhaust leaves the cylinder, then exits the car through the tailpipe. Within the cylinder, the piston is connected to a part called a crankshaft, which translate the up-down motion of the piston into rotational motion. The rotational motion turns your wheels, and allows your vehicle to move.

Multiple cylinders

What I've described above are the mechanics of only on cylinder. Car engines have more than one; four, six and eight cylinders are common. Having multiple cylinders makes the engine run more smoothly and delivers a more comfortable ride.

Cylinders are usually arranged in one of the three ways, but a popular configuration nowadays is the V arrangement. In this configuration, cylinders are placed in a row, one after another, each slanting upwards roughly at a 45-degree angle. The cylinder immediately behind one will slant in the opposite direction from it predecessor, thus creating a "V".

So when you hear "V12", it means that the engine has 12 cylinders arranged in V configuration.

Source: The Straits Times Saturday, December 4 2010