Entry below had been described about the turbocharger. So, it is best to post about the supercharger. It has the same function with turbocharger, to increase the pressure of air intake to allow more air and then more fuel to enter the cylinder to produce more power but with different energy source. If the turbocharger using the exhaust gases, the supercharger actually using the energy from the engine itself, whether using belt, gear, shaft or chain directly from the crankshaft to drive the supercharger.
Above is one of the example of the supercharger, the twin-screw supercharger. It is one of the efficient among the three types of the supercharger. The working principal of supercharger is just like the turbocharger where the air is compressed and driven into the intake manifold. The compressed air then will be cooled by the intercooler and enter the engine cylinder. Compressed air means more air will be allowed to enter the cylinder and also more fuel needed according to the air-fuel ratio. More fuel means more power will be produced by the engine compared to the natural aspirated engine. Below are the types of the supercharger used by various of cars around the world.
After discussing about turbocharger and supercharger, it look like the supercharger has slight advantages compared to the turbocharger.
1. Supercharger do not suffer lag time. Lag time is the time for the engine to response when the driver press the gas pedal. It is because the turbocharger driven by the exhaust gases and it take some time for the exhaust to reach the velocity sufficient to drive the turbine. For the supercharger, the usage of belt or chain will drive the supercharger directly as the crankshaft rotate.
2. To install the turbocharger, it requires the modification at the exhaust system while the supercharger can be bolted to the engine directly. So, it is more cheaper to install the supercharger and also easy to service.
3. Because there are no lubricating oil in supercharger, it can be shutdown normally without special procedure. For the turbocharger, it must idle for about 30 seconds to shutdown so the lubricating oil has a chance to cool down.
Might want to know more about supercharger, check those links below.