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Nozzles and Injectors

Delphi diesel nozzles and injectors are fitted as original equipment by many vehicle manufacturers (including Peugeot, Renault, Citroen, LDV, Ford, Perkins, Volvo and Isuzu), covering a wide range of private and commercial vehicles, as well as industrial and agricultural truck applications. Delphi supplies a wide range of all-makes nozzles, manufactured to the same demanding standards for quality and precision as our OE product. In addition, Delphi also offers a range of remanufactured diesel injectors, assembled and tested and ready to fit straight on to the vehicle. Click on Product Function, Product Range, Service Policy and Why Buy Delphi? to jump to more information below. You can also download product brochures at the foot of this page.

Product Function
Directly secured to the engine cylinder head, the injector introduces fuel into the engine in the best form for optimum combustion. This requires the breaking down of fuel into tiny droplets, ranging in size from twenty to one hundred microns diameter, and spreading the droplets evenly through the combustion chamber. The injector consists of the nozzle-holder and the nozzle, with the nozzle having to close rapidly at the end of the injection in order to prevent the combustion gases forcing their way up into the injector.
In the more technically advanced diesel systems (i.e. EPIC, DPCN), the nozzle holder acts as a sensor for measuring the injection flow rate and sends this information back to the electronically controlled pumps.
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Product Range

The Delphi range of nozzles and injectors covers the whole spectrum of technologies and applications:

Multi-hole long-stem nozzles - Used on direct injection modern diesel engines that require an injector with a small nozzle stem diameter. These nozzles are generally used on engines fitted to commercial vehicles and for industrial / agricultural applications.

Multi-hole short-stem nozzles - Working in an identical manner to the long-stem, this nozzle was fitted to DI engines throughout the 1970’s and 1980’s. The majority of applications were fork-lift trucks and cranes.

Pintle type - Used on indirect injection diesel engines, pintle nozzles can have either long or short bodies depending on cylinder head design. The needle valve is extended to form a ‘pintle’, which protrudes through a single central hole in the nozzle body. Pintle profile can vary to suit a particular engine type.

Pintaux type -The pintaux is a variation on the basic pintle nozzle, incorporating an additional auxiliary spray hole. The auxiliary spray is directed towards a glow plug and hence aids starting under cold conditions and reduces engine knock when idling.

Delphi is at the forefront of development within all sections of the automotive industry; the nozzles and injectors range reflects this position. The two most recent developments within injector technology are now an integral part of the Delphi range and are detailed below.

Two-stage injector
The two-stage injector has been designed to combat the problem of excessive engine noise. The injector allows a low rate of fuel flow initially, followed by injection at a higher rate, reducing the rate of combustion pressure rise. This results in significant reduction of noise without a loss of power.
Special production machinery and techniques are required to set and adjust two-stage injectors at constant high pressure. In addition absolute cleanliness is necessary due to the very small nozzle spray holes. Repair of these injectors is now possible using the Hartridge combination of HH701 and HH720.

Electronic Unit Injectors
Delphi is at the forefront of development within all sections of the automotive industry; the nozzles and injectors range reflects this position.
In addition to the recently developed two-stage injector, Delphi also produces Electronic Unit Injectors. The EUI system replaces the separate injection pump and nozzle layout found in traditional diesel injection systems. It consists of 6 EUI’s, an Electronic Control Unit and various sensors and switches. Each EUI consists of a pumping element, nozzle and actuator in a single housing and works at extremely high injection pressures. Its function is to provide electronic control of the amount of fuel injected and the injection timing in order to optimise power, emissions and fuel economy.
In addition to new product, Delphi offers a range of remanufactured replacement Electronic Unit Injectors and service and repair of EUI is now possible using the Hartridge AVM2-PC test bench and additional kit (HK870 and also HK862)

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Service Policy
Delphi strongly recommends that nozzles be replaced as a complete set every 50,000km. Whilst beyond 110,000 km the whole injector unit should be replaced.

Scaled or worn nozzles are detrimental to the efficiency of diesel engines and replacement at these recommended mileages will ensure:
  • improved driving comfort
  • increased vehicle lifetime
  • reduced fuel consumption
  • improved emissions to comply with the increasingly strict European legislation.
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Why Buy Delphi?
There are many manufacturing deficiencies you can expect to find on nozzles manufactured by companies who do not have the technical capabilities and experience of Delphi. These deficiencies can have serious effects on a vehicle’s performance and ultimately question the cost effectiveness of fitting non-Delphi nozzles.

Hole Types

  1. Thrust pin finish
    The “thrust-pin” end face of a nozzle valve makes contact either with the injector spindle or the lower spring seat. The nozzle valve is spring-loaded to obtain the specified opening pressure. Poor surface finish of the thrust pin end face will cause rapid opening pressure loss through accelerated wear, thus increasing the risk of excessive exhaust smoke.
  2. Dowel holes out of position
    A difference in position between the nozzle and injector dowel locations will stress the nozzle sealing face and cause leaks and/or cracking of the nozzle.
  3. Burrs at the feed-hole breakthrough
    Burrs within a nozzle can break off and be forced into the injection holes, with consequent damage to the valve and body seats, blocked holes, or seizure of the valve.
  4. Injection hole finish
    Burrs at the internal and external “breakthrough” points will affect the spray pattern and fuel flow, with consequent reduction of engine power and increased smoke levels.
Pintle
  1. Seat position
    If the valve seating is too close to the top of, or is above, the body seat, the result will be poor sealing of the nozzle valve, thus causing increased smoke and excessive combustion noise.
  2. Burrs on the valve seat
    Burrs on, or damage to, the valve seating area will also result in poor nozzle valve sealing, thus causing increased smoke and excessive combustion noise.
  3. Pintle damage
    Damage to the pintle will change the spray form and can affect the rate of fuel delivery, which is crucial for optimum performance.
  4. Cavitation
    Cavitation occurs when fuel flowing at high velocity is subjected to a rapid pressure drop or sudden changes in direction of flow. This may be the result of a mismatch within the engine fuel injection system, the fitting of a wrong nozzle as a replacement, or of the manufacture of a replacement nozzle to the wrong design criteria.
  5. Flow curve (pintle form)
    A pintle nozzle is designed to deliver fuel at a specific rate over its entire lift range. The need to meet current and future legislation requirements is leading to complex pintle designs.
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