Delphi Multec 3.5 User Manual

Product Description Multec 3.5 Fuel Injector Application Manual
3-14 Delphi Energy and Chassis Systems
Revision: 11/05-1
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Note:
The following calculations assume an ideal constant fuel supply for
pressure vs. injector flow. Any fuel pressure control deviations from the
set point must be taken into consideration in the following calculations.
(The fuel pressure regulator gain will tend to increase pressure at very
low injector flows and decrease flow at very high injector flows. (See
Section 5.2.3.14 for fuel pump flow compensation).
Note:
In addition, the following calculations assume that the fuel supply system
is vacuum biased, meaning that the pressure drop across the injectors is
held constant regardless of the manifold vacuum level at the tip. This is
usually achieved by connecting the dry side of the regulator diaphragm
to manifold vacuum.
In a non-vacuum biased system for a normally aspirated system, the
pressure drop across the injectors increases with higher manifold vacuum.
Low engine fuel demands typically occur during conditions of high
manifold vacuums: idle and deceleration. This situation increases the flow
range requirement demands on the injector.
Injector Pressure Drop = inlet fuel pressure + manifold vacuum
Note:
For a turbocharged or supercharged system the intake manifold pressure
will increase during boost conditions, reducing the pressure drop across
the injector. (For boost, use negative vacuum (pressure) in above
equation.)
2. Engine horsepower rating
• To size fuel injector flow rate, the design engineer must determine
the engine condition where the maximum amount of fuel is
required. Initially, two conditions should be considered, peak
torque fueling and peak horsepower fueling. (Calibration specific
issues may increase these requirements – see below.)
• At peak torque, the engine requires the greatest amount of air and
fuel per cylinder event. At peak horsepower, the engine typically
requires less air and fuel than peak torque but delivery time per
cylinder event is greatly reduced due to the higher rpm.
• Data analysis has shown that if an injector can provide enough
fuel per cylinder event to cover the peak horsepower point there
will be sufficient fuel to cover the peak torque condition as well.
For these reasons peak horsepower is usually chosen for baseline
fuel injector flow design.

Delphi Multec 3.5 Specifications

General

Brand	Delphi
Model	Multec 3.5
Category	Laboratory Equipment
Language	English