Both force extra air into the engine so it can burn more fuel, but they get their drive from different places. Use the buttons to compare them: a turbocharger driven by exhaust gas against a supercharger driven by a belt.
A turbocharger and a supercharger are both forced induction devices. They squeeze more air into the engine than it would draw on its own, and because an engine can only burn fuel in proportion to the air it gets, that extra air means more power from the same displacement.
The difference is where they get the energy to spin. A turbocharger is turned by the exhaust gas leaving the engine: the turbine and its compressor sit on one shaft, so the exhaust drives the intake. A supercharger is turned mechanically by a belt from the crankshaft, so the engine itself drives it.
That one difference sets up every trade-off. Because a turbo waits for exhaust to build, it has some lag; because it reuses waste energy, it is efficient. Because a supercharger is geared straight to the crank, it responds instantly; because the engine must power it, it costs some fuel. Seeing the two side by side makes clear why the right choice depends on the car.
An engine makes power by burning fuel with air, and it can only burn as much fuel as the air allows. Force more air in and it can burn more fuel, so both devices exist to feed the engine a denser charge.
In a turbocharger the engine's exhaust is put to work. It flows across the turbine on the hot side and spins it, turning exhaust energy that would otherwise be wasted out of the tailpipe into rotation.
The turbine and the compressor share one shaft, so spinning the turbine spins the compressor on the cold side. It draws in fresh air and squeezes it, raising the pressure on its way to the engine.
Because the turbo waits for exhaust to build, there is a short delay — lag — before boost arrives. Once the engine is working hard and the exhaust is flowing, though, it delivers plenty of boost while reusing energy, which is why turbos suit efficient and high-output engines.
A supercharger is driven mechanically. A belt runs from a pulley on the engine's crankshaft to a pulley on the supercharger, so whenever the engine turns, the supercharger turns too, and its counter-rotating rotors force air straight into the intake.
Because it is geared to the crank, the supercharger's boost arrives the moment the engine speeds up, with no waiting — that is its strength, and it feels especially strong low down. The trade-off is that the engine has to spend some of its own power turning the belt, which costs a little fuel.
A turbo tends to be the efficient choice, good for cruising and for engines where power comes at higher revs. A supercharger tends to be the responsive choice, good where instant low-speed punch matters more than saving fuel. Some engines even use both, letting each cover what it does best.
Both force more air into the engine, but they are driven differently. A turbocharger is powered by the engine's exhaust gas, while a supercharger is powered by a belt from the engine's crankshaft.
Because it waits for exhaust to build up. When you open the throttle the engine has to make more exhaust before the turbine spins faster and the compressor catches up, and that wait is the lag.
Because it is geared straight to the crank. The moment the engine speeds up, the belt turns the supercharger faster too, so boost rises immediately with no waiting for the exhaust.
A supercharger, because the engine has to spend some of its own power turning it. A turbocharger reuses energy that would otherwise be wasted out of the exhaust, so it is the more efficient of the two at cruise.
A supercharger. Its boost is there as soon as the engine revs, so it feels strong low down. A turbocharger tends to build its best boost higher up the rev range, once the exhaust flow is strong.
Yes. Some engines are twin-charged, using a supercharger for instant low-speed response and a turbocharger for efficient high-speed boost, with the two handing over as engine speed rises.