What is engine size, and why does it matter?

By Jez Spinks, 02 Jun 2016 Car Advice

What is engine size, and why does it matter?

Bigger is better, right? Not always. Smaller, modern engines use less fuel, and smart technology means many new engines are just as powerful as big, old, gas guzzlers

If you’ve ever heard or read about terms such as 2.0-litre, cubic centimetres (cc) or engine displacement, they all relate to the size of a car engine. 

The size is determined by the amount of space – or volume – there is in the engine’s cylinders, which store the mixture of air and fuel that is burned to create the energy required for turning the wheels. 

The number of cylinders an engine has also varies greatly, typically ranging from 12 to 3 – although there are cars with as many as 16 and as few as 2 cylinders – the highest numbers are usually associated with superfast supercars. 

If we take a 2.0-litre four-cylinder engine as an example of what is often found in popular modern cars, each of those cylinders has a volume of about 500cc (or half a litre). Manufacturers round up numbers so a 2.0-litre engine might actually have a more specific 1997cc. 

A basic guide to engine size is that the bigger it is, the more powerful it is. 

However, big engines are also typically less efficient – using more fuel than smaller engines. 

The modern engine trend is to downsize, using fewer, or smaller cylinders for lower fuel consumption, then adding a turbocharger to the engine as compensation. In most cases, smaller turbocharged engines produce more power than the larger non-turbo engines they have effectively replaced. 

Some manufacturers, including Ford and Volkswagen, even offer a 1.0-litre three-cylinder engine in some of their models which uses very little fuel but manages to feel as powerful as a bigger engine. 

Ford’s little 1.0-litre EcoBoost turbo engine, for example, is the same size as an A4 piece of paper, yet produces almost as much power and torque as the bigger, 1.8-litre four-cylinder in the Toyota Corolla: 92kW v 103kW and 170Nm v 173Nm. 

And the small 1.6-litre four-cylinder turbo found in the Peugeot 308 GTi 270 produces 201kW of power – just 8kW fewer than the significantly bigger 3.6-litre six-cylinder engine found in the Jeep Wrangler. 

As engineers continue to find ever more ingenious ways to extract more power while using less fuel, engine size no longer matters like it used to.

Now find out what DOHC means.