How do turbos work, and how do they differ from superchargers?
Turbocharging makes everything better, right?
Any survivors from the 1980s will remember the term could be loosely applied to anything – turbo razors, turbo sunglasses and turbo skateboards to name but a handful. But what are (real) turbos?
The simplest way to understand them is to consider that an engine needs to mix fuel and air to run. Turbos force more air into the cylinder, which can be mixed with more fuel to create more power. Turbos use the energy of the engine’s exhaust gasses to compress air into the engine.
How do they work?
Turbos are formed of two main parts – a turbine and a compressor. These are linked so, when the one spins, the other spins with it. As fuel in the engine is burnt, exhaust gasses are forced out of the engine at high pressure, down a snail-shaped tube to spin the turbine. This turbine spins at incredibly high speeds (up to 250,000rpm) and causes the compressor (effectively a reversed turbine) to spin. This sucks significantly more air into the engine than a normally-aspirated (non-turbo) unit, making more power.
Turbos run at immense speeds which means they operate under huge pressures and temperatures. Typically, an intercooler is paired with the turbocharger to cool the hot air coming out of it and an oil cooling system ensures the turbo itself doesn’t run too hot. Diesels, having tougher engine blocks and simpler intakes, are ideally suited to being turbocharged so all modern diesels have them.
What are the benefits?
More power is the glaring headline here, but it’s far from the only advantage. Turbo engines can make the same power as a normally-aspirated engine while using less fuel. Hence why Ford, for example, has replaced the old 1.6-litre petrol engine with a new 1.0-litre turbo – it makes the same power but uses much less fuel.
Turbos also give engines more torque – often lower down in the rev range. This means they feel much stronger around town where the extra torque makes nipping into gaps easier. Another, unexpected, advantage is that turbos actually make for a quieter engine as they muffle the sound of the intake.
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