The diesel engine is charged almost exclusively with the help of a turbocharger. The petrol engine rather features
compressors. One possibility to pump air or fuel-air mixture into the engine is the Roots charger. An improvement as compared to the G-supercharger is that the air-condensing elements
work without contact and it is has a more spontaneous reaction to the accelerator pedal as compared to the turbocharger. The turbo lag is completely absent.
Two rotors with two, three or four gaps turn around and carry air in their gaps. The air cannot flow back because the rotors interlock in the middle. There is no friction with the wall or among one another because both
rotors are precisely guided at the outside by a (lubricated) gearwheel. In this case the drive occurs via the timing belt, however, it is also possible via gearwheels or a chain.