Engine replacements
Many manufacturers produce a series of models with the
same basic frame fitted with engines of differing
capacity. No approval is required if the smaller capacity
engine is replaced by a larger capacity engine from the
same series provided the brakes and suspension from the
larger capacity motorbike are fitted and no modification
is required to the frame.
The fitting of any other alternative replacement engine,
superchargers or turbochargers will require individual
approval in accordance with Section 3.
this is taken from a QLD Vehicle Standards Buelletin
2.1 CHOICE OF REPLACEMENT ENGINE
A manufacturer’s standard or optional engine should be selected and installed using all the
standard components for that vehicle model. However, where this is not practicable, the following
requirements should be met:
Any replacement engine should be of similar mass and power output to that of an engine
fitted by the original vehicle manufacturer as standard or optional equipment;
When the replacement engine is larger in power output than an engine offered by the
vehicle manufacturer as standard or optional equipment, the vehicle must be equipped
with any necessary upgrading of equipment, e.g. brakes, front suspension, etc.; and
The power and/or torque of the replacement engine must not exceed the capacity of the
vehicle driveline.
Using the engine manufacturer’s published specifications, the dimensions of the selected engine
should be checked against the vehicle to ensure that:
the engine, together with all of its components, fits into the available space without major
frame, body or other modifications;
the engine mass and location of centre of mass must not result in excessive mass on the
front or rear suspension;
the location of ancillary equipment, such as the cooling system, the intake and exhaust
systems must be suitable for the vehicle layout; and
the replacement engine must be installed in a position and on an angle that allows the
driveline to operate correctly.
If the installation requires modifications to the vehicle structure, such as chassis rails and firewalls,
the modification must be performed in accordance with the applicable LH Code(s)