Turbocharger: forcing air into the engine

Petrol and diesel engines need two things: air and fuel. To get more power you need at add more of both. Too much air on its own will lead to the cylinders getting too hot and failing; too much fuel on its own will lead to the engine spluttering to an undignified (and uneconomical) halt.

Under normal conditions, there’s a limit as to how much air you can get into an engine, which is determined by atmospheric pressure.

If you could force more air into an engine, you could then add more fuel and the result would be more power – enter stage-left the turbocharger.

Essentially the turbocharger is a hair-dryer, but instead of the power coming from your household electricity supply it comes from the exhaust gasses produced by the engine. These gasses spin a little turbine (fan), which blows fresh air into the engine.

The big downside is that the engine has to be revving fast enough to be able to spin the little fan, so when you’re engines just idling the turbocharger isn’t doing very much. When you’re revving the engine the turbo gets cracking and blows like a veritable hurricane. This can lead to a fairly indiscrete power delivery, where the fast you go the more power the engine produces and before you know it you’re a) out of control and b) have a speeding ticket.

Electronics and modern materials have helped this, but they say you can always tell when an engine has a turbo: there’s a lag between pressing the go-pedal and actually going.