AA Buyer's Guide: Engine configurations
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Over the decades, countless engine configurations have been used with varying degrees of success. There have been single-cylinder cars like the tiny Peel P50, for example. At the other end of the scale, Volkswagen Group has produced a huge 8.0-litre W16 engine for Bugatti, which is used in the Veyron and Chiron models and is capable of up to 1177kW.
Selecting the right engine is important for manufacturers, as it directly affects important characteristics like power, economy, exhaust pitch and even the weight balance.
The inline three
Not so long ago, inline three-cylinder engines were only found on motorbikes or tractors where excess noise wasn’t an issue.
In recent years, however, a number of car manufacturers have revised the “straight three” engine, refining it and adding turbochargers to increase both power and improve economy. Large manufacturers like VW favour three-cylinder engines and these are utilised in two out of three variants of the Polo and T-Cross currently on offer.
These engines are also particularly popular in the Japanese kei-car scene due to their compact size and efficiency, where a maximum 660cc capacity is mandated.
The humble configuration of three cylinders is not only efficient, it can be powerful too. Take the Toyota GR Yaris: with a displacement of only 1618cc, it produces a jaw-dropping 200kW/370Nm! Fuel efficiency is 7.6l/100km, with a CO2 rating of 172g/km.
We predict the popularity of inline threes continuing for the foreseeable future.
The inline four
The inline four is perfect for front-drive applications due to its compact dimensions. These engines are excellent for a wide range of power requirements - they can either be boosted with a turbo for some extra “oomph”, or be run very economically (in hybrids, for example)
But sometimes displacement is limited, as they require balance shafts. Toyota, Honda and Mazda all currently favour four-cylinder engines, tweaking and perfecting their designs over the years.
They’re also well suited to mid-mounted applications such as in the MG F/TF of yesteryear with its memorable Rover K-series engine and (of course) the classic Toyota MR2.
The flat four and flat six
Flat fours and sixes (sometimes referred to as “horizontally opposed” engines) offer the benefit of a very low centre of gravity, along with their own signature exhaust note.
Over the years, several manufacturers have opted for these configurations, including Subaru, VW and Porsche.
These engines lack the height of many other engines, but they can be fairly wide which means serviceability isn’t always the best; anyone who’s attempted to replace the spark plugs on a Subaru BRZ or Toyota 86 may know the feeling all too well.
The mighty V6
The V6 engine is a bit of a compromise –not too awkward to find space for compared with an inline six, but can be used in transverse and longitudinal applications easily.
The V6 offers good power, but also requires balance shafts to remain silky smooth. It also tends to be more thirsty.
V6 petrol engines have good performance and sound. An example would be the glorious V6 Alfa Romeo Busso engine, which was produced for 26 years due to its popularity. Alfa Romeo still uses a 2.9-litre V6 engine in the Giulia Quadrifoglio sedan.
Kia even uses a 3.3-litre V6 engine in the Stinger GT Sport, which produces 274kW/510Nm.
The much-loved V8
The benefit of V8s is that they are not as long as an inline six and have a rather boxy form factor. They develop considerable power, and in traditional format the cam gear is driven by pushrods.
The main flaw (or benefit, depending on how you look at it) is the V8’s uneven firing order - this is what gives it that signature growl.
Although it’s an older design, there are still quite a few new V8s available to buy from new in New Zealand. Examples include the Jaguar F-Type R, BMW M8 Competition and the Ford Mustang.
Engines are usually the result of a series of compromises. Many manufacturers are looking towards the future and reducing fuel emissions, moving towards being completely electric within the next decade.