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How to look after superchargers

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While turbocharging is a far more popular and efficient means of enhancing engine power and increasing efficiency, supercharging has not disappeared completely. Both systems perform the same basic tasks: forcing more air into an engine so more fuel can be burnt, creating extra power. For more information on the various types, see our earlier blog on the topic.

Which cars are fitted with superchargers?

While fitted, more commonly, to high-performance historic vehicles, you can bag a supercharged car from a typical forecourt. While Lancia pioneered the idea in production, large-engined Jaguars, Land and Range Rovers, BMWs, Mercedes-Benz, plus various MINIs and Lotus cars tend to be the most popular examples in the UK. Some cars offer a combination of super and turbocharging, such as the Volkswagen Group's Twincharger 1.4-litre TSI engine and Volvo's T6 four-cylinder petrol engines. On twin-charged cars, a supercharger promotes high power at low engine speeds, while a turbocharger takes over as the RPMs increase.

What is the difference between a supercharger and a turbocharger?

Superchargers do not use energy from exhaust gases. Instead, they are driven by other means. This can be via a simple drive belt, or by electric power on newer cars.

How do I maintain a supercharger?

Superchargers are lubricated by a dedicated oil supply that protects their bearings and innards. Many car-makers declare that this oil supply need not be drained but experience has demonstrated that oil changes maximise supercharger longevity.

Superchargers also need clean air. Therefore, regular air filter changes and checking the supercharger oil level at every service are vital. Typically, plan to replace the supercharger oil every 50,000 miles.

Should your car's supercharger possess a mechanical drive belt, it should be inspected, along with any idler/tensioner bearings, at every service.

What goes wrong with superchargers?

While noise indicates wear, it is easy to confuse a rattling drive belt idler, or even a worn engine component for a damaged supercharger. Such misdiagnosis could be an expensive mistake. Should you suspect that your supercharger is worn, disconnect the drive belt; the engine will still run but at reduced power. Should the noise still be present, the supercharger can be discounted as the cause.

Some noises are normal. A whistle (a very common characteristic among early supercharged Jaguars, for example) should not worry you, although check for air leaks in the pipework.

Bearing wear can cause serious damage. Modified Roots superchargers, especially are prone to worn front and rear bearings, as well as the additional drive shaft bearings within the 'snout' casing. The resultant movement within the rotors creates noise. This should not be ignored, because the racket stems from their rotating tips striking the housing. Unsurprisingly, this damages both surfaces and, in advanced cases, the situation can render the supercharger as scrap, should the problem not be caught in time.

Thankfully, a competent DIYer can execute a bearing change at home, provided that a hydraulic press and a torque wrench are at hand. Should you not be particularly handy, at least you can turn to a handful of dedicated specialists who can repair your supercharger for a fraction of the cost, compared with a new replacement from a main dealer.


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