Oil intensified common rail injectors

Oil intensified common rail injectors that combine a common-rail non-intensified injector with an oil-intensified injector. The invention also uses fuel (common rail) pumps that are commercially available since the injector does not rely on this pump for intensification function. Also, since the pressure of the fuel pump is limited to lower than the intensified pressure, the injected pressure is limited to the unit injector; this eases the rail and tube requirements to this lower fuel rail pressure. The injector operates up to this limited pressure with no intensification. Also a separate oil system is configured to operate a hydraulic intensifier. Thus the system is able to achieve very high injection pressure without common rail pump, rail, fitting and jumper tube limits. The oil system does not need to operate or run unless these elevated pressures are required. Embodiments using direct needle control are disclosed.