Gasoline Engine Management Systems

Delphi Multec® GDi Multi-Hole Fuel Injectors

Delphi Multec® GDi Multi-Hole Fuel Injectors are designed for homogeneous combustion gasoline direct injection engine applications.  This family of flexible packaging and performance-optimized injectors features an inwardly opening valve group and a multi-hole spray generator with enhanced multi-pulse operation and reduced minimum fuel capability.

The Multec 12.1 GDi Injector is capable of high pressure, up to 250 bar nominal system pressure with 300 bar maximum.  Additional enhancements for low particulate number (PN) emissions are available with the Multec 14 GDi Injector, which offers even higher pressure operation of 350 bar nominal system pressure and 400 bar maximum.


  • Moving mass emits 1 dB lower acoustic noise than the rest of the industry
  • Excellent fuel deposit robustness
  • Very low tip leak valve group provides PZEV-capable fuel seal
  • Flexible spray pattern with low penetration reduces fuel impingement on cylinder walls and allows flexible mounting
  • De-coupled armature eliminates needle bounce at closing
  • Corrosion resistance, flow performance, and linear range to accommodate the requirements of ethanol-blended fuels
  • Stainless steel mesh inlet filter robust to corrosive fuels and sharp particle contamination as compared to typical nylon mesh filters
  • Magnetic circuit is compatible with 50 V to 65 V boost voltage
  • Faster response times allow smaller injection quantity and greater working flow range
  • Monotonic flow curve shape for optimum control of fuel delivery from very low pulse widths in the ballistic range through full opening in the linear operating range at higher pulse widths
  • De-coupled armature allows up to 400 bar operating pressure (Multec 14 Injector) with minimal driver energy; lower than previous 100 bar designs
  • Both the Multec 12.1 and Multec 14 Injectors can operate with dwell times as low as 0.3 msec during multi-injection operation for Euro 6 particulate emissions number
  • Multec 14 Injector 400 bar O-ring, with dual back-up rings, sealing system for high pressure.  Multec 15 compatible at -40°C
  • Multec 14 Injector 6 mm tip diameter for ease of packaging in today’s small bore engines
  • Multec 14 Injector pressure vessel optimized with only two hermetic laser welds for robustness and reliability

Typical Applications

Delphi Multec GDi Multi-Hole Fuel Injectors can be applied to any size gasoline engine, from small displacement turbo-charged engines to large displacement engines, including central mount applications.  The finely atomized spray allows optimum charge distribution for reduced emissions on cold start and for future combustion processes such as gasoline homogeneous charge compression ignition (HCCI).

The Delphi Multec® GDi Multi-Hole Fuel Injector tip is designed for fuel deposit robustness.

Targeted Performance Specifications


Multec 12.1 Injector

Multec 14 Injector

Static flow rate

Up to 20 g/sec

Up to 18 g/sec

Maximum fuel pressure

300 bar

400 bar

Qmin flow

(Compensated with ICLC algorithm < +/- 10%)

2.0 mg/pulse

2.0 mg/pulse

D32 sauter mean diameter (SMD)

6 µm (at 200 bar)

4µm (at 350 bar)


14 µm (at 200 bar)

10 µm (at 350 bar)

0 after inject (no bounce)

No bounce at close

No bounce at close

Pulse to pulse precision at 0.4 msec PW

0.6% COV

0.6% COV

Cone angle as required by combustion

40° to 90°

40° to 90°

Tip diameter

7.5 mm

6 mm

Opening energy

138 mj

129 mj

Pressure vessel — (hermetic welds)



Performance Advantages

Delphi Multec GDi Multi-Hole Fuel Injectors offer flexible spray preparation options that allow customization of the spray shape to accommodate a wide variety of combustion chamber shapes.  The small particle size provides rapid vaporization for good mixture preparation.  An optimized magnetic circuit provides rapid and consistent response times and increased linear flow while using industry standard drive.  Delphi Multec GDi Multi-Hole Fuel Injectors are also designed to reduce acoustic noise.

Delphi uses an innovative femto-second laser manufacturing process to drill the nozzle holes.  This allows complete flexibility in the nozzle hole diameter and taper so that each spray plume’s penetration and fuel mass is optimized for the combustion chamber.  The process reduces cost and allows flexibility for positioning the holes, thus enabling higher quality, improved injector performance and low particulate emissions.

The injector tip is designed for fuel deposit robustness (reference SAE 2009-01-1495: Engine Test for Accelerated Fuel Deposit Formation on Injectors Used in Gasoline Direct Injection Engines).

The Delphi Advantage

Delphi offers the benefits of vast experience producing hundreds of millions of gasoline fuel injectors for customers around the world. That experience has led to product and manufacturing process improvements which have helped eliminate contamination-related failures and provided other quality and cost advantages. Delphi's in-depth knowledge of systems and the combustion process help optimize injector performance.

As a global leader in engine management systems technology, Delphi can help manufacturers meet emissions requirements, improve fuel economy and enhance performance. Delphi is a source for high value solutions and our systems approach is built into every product. Delphi's flexible engineering approach encourages collaboration. And, Delphi has a thorough understanding of automotive markets around the world and a global network of resources.