BRP ROTAX 914 Series, Operator'S Manual

Page: 77 / 96

Effectivity: 914 Series
Rev. 0 BRP-Rotax Page 7-11
August 01 2019
7.6) Turbo charger and control system
General
The ROTAX® 914 engine is equipped with an exhaust gas tur-
bocharger, making use of the energy in the exhaust gas for pre-
compression of the intake air (boost pressure).
Regulation boost
pressure The boost pressure in the airbox is controlled by means of an
electronically controlled flap (waste gate) in the exhaust gas
turbine.
NOTE
The waste gate regulates the speed of the turbo charger and
consequently the boost pressure in the airbox.
Throttle position
The required nominal boost pressure in the airbox is deter-
mined by the throttle position sensor mounted on the carburetor
2/4. The sensor’s transmitted position is linear from 0 to 115 %
corresponding to a throttle position from idle to full power.
100%
115%
0%
Figure 8: Throttle position
Nominal boost
pressure
For correlation between throttle position and nominal boost
pressure in the airbox, refer to the diagram.
ATTENTION
As shown in the diagram, the throttle position at 108 to 110 % results
in a rapid rise of nominal boost pressure. To avoid unstable boost,
the throttle should be moved smoothly through this area either to full
power (115 %) or, on a power reduction, to max. continuous power
(100 %).
In this range (108 to 110 % throttle position) small changes in
throttle position have a big effect on engine performance and