Multec 3.5 Fuel Injector Application Manual Product Description
Delphi Energy and Chassis Systems
Revision: 11/05-1 3-37
Dynamic fuel flow is a measure of dynamic injector performance. It is
typically measured at a 2.0 ms pulse-width and a 10 ms repetition rate for
Multec 3.5 port fuel injectors. The 2.0 ms pulse-width was chosen to
maximize low pulse-width flow accuracy. Dynamic fuel flow is affected
by opening response, closing response, and static flow. The following
design factors directly determine opening and closing response (see
section 3.9).
• Magnetic circuit design (including stroke)
• Core spring load
• Differential fuel pressure
• Sealing diameter
• Friction/fluid damping effects
Static fuel flow is a measure of maximum flow capacity and is measured
at 100% duty cycle. The following design factors affect static flow:
• Sealing diameter
• Seat geometry
• Fuel pressure
• Director hole size
• Valve Stroke
The injector is set for both static and dynamic flow during the
manufacturing process.
Multec 3.5 injectors are capable of static flow rates from 1.3 to 4.0 g/s at
400kPa (58 psi.) Static flow rates above 4 g/s are feasible, but may
require relaxed flow tolerances due to increased pressure sensitivity.
The injector set point flow rate is normally determined for each static flow
rate to optimize low voltage and low pulse width performance.
3.13.1 Flow Test Fluid Specification
All production and audit injector flow rate measurements will be made
with the following fluid unless otherwise specified:
Stoddard Solvent (Delphi Materials Specification Number M52625)
Specific gravity – 0.788 +/- 0.25% @ 15.56°C
Absolute viscosity – 0.997+/- 0.20% cP @ 20°C
Note: Production injector flow values are specified in Stoddard Solvent
only. Any flow values provided in gasoline are for reference.
As an approximation, injector flows in gasoline will be 1.0 to 2.5% less
than those in Stoddard Solvent.
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