air flow in a variable turbocharger With the help of the fan supplied, air is pressed into the turbo-charger; function of the guide vanes: if the engine speed is too low, the cross-section is reduced, the output rotor turns more quickly. description ordernumber 442 see also: common rail injector (with bottommounted solenoid valve) radiator cap volume controlling unit (in-line injection pump) variable geometry turbocharger