Turbo: It forces air into the engine so that the combustion can take place. It is very common in cars with Diesel engines.
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The turbocharger works like a small and powerful fan since its blades move very fast. It takes the natural air, compresses it and forces it inside of the cylinders. When it gets damaged, it may produce a very loud noise, similar to a screech, because the axle brushes against the bodywork. White or black smoke may also come out from the exhaust pipe.