What is engine size, and why does it matter?

Bigger is better, right? Not always. Why doesn't displacement matter as much as it used to?

engine size

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's engine. 

Engine sizes

The size of an engine is determined by the amount of space (volume) there is in an engine's cylinders. This is where the mixture of fuel and air is ignited to make the energy required to turn the wheels. Cumulatively, the volume between all the cylinders denotes the engine's size. 

The number of cylinders an engine has also varies greatly, typically ranging from 12 to three – although there are cars with as many as 16 and as few as two cylinders – the highest numbers are usually associated with supercars and big utes. But generally the smaller the engine size and the smaller the engine capacity, the more fuel efficient your car is. 

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. 

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

The modern approach is to use smaller engine sizes but find ways to boost their power outputs, like through turbocharging. In most cases, smaller turbocharged engines can produce more power than the larger non-turbo engines they have effectively replaced. To top it off, those smaller turbocharged engines are still more fuel efficient while producing more power and torque. 

engine size
Cross-section view of a turbocharger

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 much larger-engined cars. 

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. 

engine size

Engine size used to be the be-all-and-end-all indicator of a car's performance, but current technologies allow for increased fuel efficiency while returning better power and torque figures. The downside of this is the loss of the unique characteristics of larger naturally aspirated engines that make them fun to drive. That said, turbocharged engines are fun to drive in their own way. 

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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.


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