What does your engine type and size really mean?

With so many technological innovations and complex abbreviations, it can be difficult to know where to start when faced with choosing a new car with an appropriate engine for your needs. Here, we give you a jargon-free breakdown of the key things you need to know when comparing engines.

Petrol vs diesel

Petrol and diesel behave differently, so need different engines to compensate. Petrol is a more volatile compound, ignited by a spark in the engine, while diesel uses compression alone to drive the pistons.

Petrol engines

Petrol engines generally have a higher power-to-weight ratio and are able to rev at a higher rate than their diesel counterparts, meaning that petrol engines are often better for a quick burst of speed. Petrol engines tend to be cheaper than diesel as they are more widespread, simpler and require servicing less often, as well as being quieter than diesel models. Petrol engines are evolving rapidly in terms of efficiency, with Ford taking the lead through its multi-award winning 1.0-litre EcoBoost engine.

Diesel engines

Super-charging and other technological advancements have now almost brought diesel engines in to line with the potency and popularity of petrol, but diesel also has some advantages all of its own. Diesel itself contains around 15% more energy and diesel engines are 15% more efficient at converting fuel into kinetic energy than petrol models, meaning that emission levels are often significantly reduced. Diesel engines produce more torque at low ranges, as well as less waste heat and carbon monoxide. They have less components and double the life-expectancy, as components are usually more hard wearing.

Hybrid/electric engines

Hybrid electric vehicles (HEVs) are powered by a combination of internal combustion (petrol/diesel) and high voltage electric engine(s). Billed as an eco-friendly stopgap between fossil-fuel and renewable energy source cars, the electric engine is used in low-performance scenarios (such as city driving), while the internal combustion engine is used at higher speeds. Hybrids are not known for great acceleration or cornering, but save fuel and money through innovative features, such as enabling the internal combustion engine to re-charge the electric engine batteries while on the move.

Engine size

Cylinders

A cylinder is the part of the engine where fuel is burned to drive the pistons, which then rotate the wheels. The amount of cylinders a car has determines its size (when compared to a car of the same age) with most models containing three, four, six or eight cylinders, referred to as V3 – V8.

Litres

The amount of fuel that a cylinder can hold is measured in litres. The total number of litres that an engine can hold determines its overall power and is used in car model names, e.g. 1.5-litre/2.0-litre, etc. Engine power determines acceleration, top speed and towing ability – however, engines have improved so much in recent years that a 1.4-litre engine can now produce the same amount of power as a 2.0-litre engine from a decade ago. Mazda have taken a lead on this initiative, promising to increase engine efficiency by a further 50% by 2020.

Engine Positioning

Front engine

Front engine cars are the most common of the three types, affording protection in the event of a head-on collision and enhanced cornering, because the weight of the engine will lead the car into the corner, not causing the back end to slide outwards. Having the engine at the front also helps to keep all the mechanics centralised, putting the engine close to the radiator and other features, such as the wiper fluid.

Rear engine

Rear engine cars often have better grip, as the weight distribution sits above the rear tyres. However they can lose out on handling as the weight can make the tail more unwieldly. The engine also takes up valuable boot-space that is rarely compensated for at the front. These factors combined mean that rear engines are usually for smaller, or sportier, cars only.

Central/mid-engine

A centralised engine gives the car better weight distribution, which means better handling. This type of engine is usually used on sports cars that require advanced precision without having to worry about the engine taking up additional cabin space, such as on the Nissan GT-R.

Drivetrains

Front-wheel drive

Front-wheel drive cars are often cheaper and lighter as fewer components are required to transfer power from the engine to the wheels. They get better traction (especially in bad weather) but can lack handling as the nose becomes heavy and wheels are required to perform two actions at once – accelerating and steering.

Rear-wheel drive

Rear-wheel drive cars tend to be more robust as the power is transferred through a solid axle, as well as more balanced in terms of weight and therefore handling, which is why this method is often deployed in sports cars (and emergency services vehicles).

4X4 (all-wheel drive)

All-wheel drive cars are no longer just for off-roaders. The improved traction that serves all-terrain vehicles so well is now also deployed in some cruisers and sports cars, balancing handling performance with the ability to go just about anywhere. The main disadvantages are weight and cost, with all the hardware required becoming a drain on performance as well as your wallet.

If you want more expert advice on choosing a new car with the right engine, why not call on the experts at your local Perrys dealership today?