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: injection-nozzle holder with hole-type nozzle and pintle-type nozzle delivery valves Cummings PT fuel system variable geometry turbocharger