What is a supercharged engine?

They sound quite exciting and they can help to make your car go faster. But what is a supercharger, and how does it work?

Chris Rosamond
Sep 1, 2021

A supercharger is a mechanical device that compresses air and shoves it into your engine faster than it would get there under atmospheric pressure alone. Why? Because it helps to make your car go faster.

The theory is simple. As we all learned at primary school, air (or rather the oxygen in it) is one of three essential ingredients needed for combustion to take place. Full marks for paying attention if you know the other two are heat and fuel. When you pump a lot more air in with a supercharger, you can also add a lot more fuel, and this more potent mixture explodes with increased energy when the spark plug ignites it. That translates to more power from the engine.

Supercharging has been a favoured way of adding performance to an engine - especially in racing cars - since almost the dawn of motoring. You may even have heard of the famous ‘Blower Bentley’ racers that took on Mercedes at Le Mans in the 1920s, they were named for their large superchargers designed to blow pressurised air into the engines. Mercedes, too, has history with supercharged designs, and their 1920s ‘Kompressor’ models spawned a badge the company still uses for modern supercharged engines.

So the superchargers we’re talking about here have nothing to do with electrification, although you may have noticed that Tesla has chosen the name Supercharger for its rapid charging network.

Fans of Jaguar and Range Rover products may know top performance versions from both companies are powered by muscular supercharged V8 engines, but in recent years the tech has fallen out of favour. That’s because, like the car’s water pump or alternator, a supercharger takes its power from the engine. In other words, to make power, it uses power. This adversely affects the car’s performance and its fuel consumption - not good when manufacturers are under pressure to make more efficient cars.

Because they’re more efficient, turbochargers have to a large extent replaced superchargers. Even so, there are still some supercharged cars on the market so here’s what you need to know about the technology.

How does a supercharger work?

The supercharger is powered by the engine, via a pulley attached to the crankshaft. The faster the engine turns, the faster the little impeller inside the supercharger spins. The impeller compresses the incoming air and allows more of it to be directed to the engine, where it produces more power.

The faster the engine turns, the more compressed air the supercharger produces, and the more power the engine makes.

Which cars have a supercharger?

Aside from the Jaguar and Land Rover models mentioned above, there aren't that many new cars using the technology, but in recent years, the first-generation Mini Cooper S of 2001-2006 was supercharged, as was the Mercedes SLK 200 Kompressor of 2004-2010.

Today, VW champions supercharging as a way of increasing efficiency, but only in combination with a turbocharger that is powered by exhaust gases and not directly by the engine.

Volkswagen's 1.5-litre TSI Evo engine that powers some versions of the Golf is supplemented by both a turbocharger and a supercharger, in what the company calls 'twin charging'. In this engine, the supercharger works at lower engine speeds with the turbocharger providing assistance as the engine speed rises.

How do I recognise a supercharged engine?

It’s quite difficult since car makers tend not to make much noise about supercharging, while others will use a turbocharger or a supercharger or even both together, yet still badge them the same.

Some Audi TFSI engines are supercharged, while Volkswagen badges its own supercharged engines as TSI, which are used to power a number of mainstream models including the VW Golf, T-Roc, and Arteon.

 

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