Common-rail direct fuel injection (CRDi) is a modern variant
of direct injection system for diesel engines, It features
a high-pressure (over 1,000 bar) fuel rail feeding individual
solenoid valves, as opposed to low-pressure fuel pump feeding
unit injectors (pump nozzles) or high-pressure fuel line
to mechanical valves controlled by cams on the camshaft.
Modern common-rail systems, work on the same principle,
are governed by an engine control unit (ECU) which opens
each injector electronically rather than mechanically.