How does a Turbo Work?

There’s always a way to make an engine produce more power and go faster or to use less fuel. One way is to add a turbocharger, which uses a pair of fans to harness the waste power from the exhaust of an engine and reuse it to force more air back into the engine. Everyone’s heard of turbos, but what’s exactly behind the magic?


As an engine runs it exhausts a mixture of hot gases a speed, which means that heat energy and kinetic energy is literally being wasted out the back of your car. Wouldn’t it be great if you could harness that wasted energy to make a car faster and more powerful? That’s where turbochargers come in, making use of those useful gases.

How Do They Work? 

If you understand how a jet engine work, you’re halfway to knowing how a turbocharger operates. Jet engines create power by sucking in cold air at the front, then squeezing it into a chamber where a air/fuel mixture is ignited. Hot air is then blasted out the back and power is created. As the hot air exits it passes by a turbine that drives a compressor at the front of the engine. This then pushes more air into the engine to make the air/fuel mixture needed. Turbochargers operate similarly except they use the exhaust from the piston engine to drive a turbine. So essentially a turbocharger uses waste energy to create more power. How good is that?

A turbocharger features two little air fans on shaft that spin around at the same time. One fan is called the turbine, which sits in the exhaust stream from the engine. As hot gasses are blown across blades of the turbine, the shaft rotates the second air fan (the compressor). The compressor is located inside the engines air intake, so as it spins, more air is drawn into the engine.

A problem that arises from this is that as you compress a gas it gets hotter.  Hot air is less dense and less effective at helping the fuel to burn. This means that the air coming from the compressor needs to be cooled before it enters the cylinders. Heat is removed from the gases by passing it over a heat exchanger that directs it elsewhere.

Advantages and Disadvantages 

Turbochargers can be used with petrol or diesel engines and the basic advantage is that you can get more power out of the same size of engine. More power means more energy output per second, which technically means you need to burn more fuel. This means that turbocharged engines in theory are no more fuel efficient than ones without. However, engines with turbochargers can be created smaller and lighter, making for a more fuel efficient car. Additionally, turbocharged engines can burn fuel with more oxygen and they burn it more cleanly, making less air pollution.

The problem with turbochargers is that they aren’t always as fuel efficient as manufacturers promised. Sometimes, naturally aspirated engines are actually significantly more fuel efficient than a turbocharged counterpart. Another problem is that turbocharges tend to be make the engine less reliable as it adds another layer of mechanical complexity. More power out of the same engine can also create additional stress that the engine was never intended to handle. One other problem is that there can be a delay (turbo lag) between when you accelerate and when the turbo spools up.

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  • Ben

    From his early days playing the original Gran Turismo and with his Hot Wheels car set, Ben has had a long interest in all things automotive. His first foray into the world of automotive journalism was way back in 2009 and since then he has only grown more interested in the industry. Ben also runs and heads up the video production side of Garage Dreams, focusing on small informative documentaries about some of the world's most legendary cars.

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