Delphi Multec 3.5 User Manual

Software Multec 3.5 Fuel Injector Application Manual
5-16
Delphi Energy and Chassis Systems
Revision: 11/05-1
Figure 5-3 - Sequential injection timing considerations (4500 rpm)
The following factors affect fuel residence time in the manifold and need
to be considered when calibrating injection timing:
• As RPM increases, the time available between valve open events
decreases and the fuel pulse-width and fuel transport time in crank
angle degrees increases. These effects combine to reduce the fuel
residence time.
• Reversion air pulse occurs at valve closure. This can affect the
injector spray geometry, causing increased manifold wall wetting.
Delaying injection timing slightly can reduce disruption of the spray.
• During intake and exhaust valve overlap, exhaust gas will flow past
the intake valve heating and displacing liquid fuel still on the intake
valve. This will aide in fuel vaporization. If fuel spray timing is late,
this back flow of exhaust can disrupt the spray geometry.
• Increasing fuel injector to valve distance will increase fuel transport
times and reduce fuel residence time.
• the actual spray particle velocity varies throughout the cross section of
the spray. Smaller particles slow down faster and take longer to get to
the valve. For longer pulse-widths some of these smaller particles
may arrive at the valve when the valve is open.
For some engine applications and conditions, the injection timing may
require modification from the optimum fuel residence time goal. Airflow
and reversion pulses from other cylinder valve actuations may displace

Delphi Multec 3.5 Specifications

General

Brand	Delphi
Model	Multec 3.5
Category	Laboratory Equipment
Language	English