4.4.5.1 The engine group may be defined by basic
characteristics and specifications in addition to the parameters defined
in 4.3.8 for an engine family.
4.4.5.2 The following parameters and specifications
must be common to engines within an engine group:
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.1 bore and stroke dimensions;
-
.2 method and design features of pressure charging
and exhaust gas system;
- constant pressure
- pulsating system
-
.3 method of charge air cooling system;
- with/without charge air cooler
-
.4 design features of the combustion chamber that
effect NOx emission;
-
.5 design features of the fuel injection system,
plunger and injection cam which may profile basic characteristics
that effect NOx emission; and
-
.6 maximum rated power per cylinder at maximum
rated speed. The permitted range of derating within the engine group
shall be declared by the manufacturer and approved by the Administration.
4.4.5.3 Generally, if the parameters required
by 4.4.5.2 are not common to all engines within a prospective engine
group, then those engines may not be considered as an engine group.
However, an engine group may be accepted if only one of those parameters
or specifications is not common for all of the engines within a prospective
engine group provided the engine manufacturer or the shipowner can,
within the technical file, prove to the Administration that such a
transgression of that one parameter or specification would still result
in all engines within the engine group complying with the NOx emission
limits.