Air Flow; Boost Pressure Control; Ambient Air Pressure And Temperature Sensors (Aapts) - Rotax 915 i A SERIES Operator's Manual

Air Flow

Boost pressure
control
Over boost valve
Ambient Air Pres-
sure and Tempera-
ture Sensor
(AAPTS)
Page 7-14
December 01 2017
The compressor side of the turbocharger sucks air true the air-
filter and pushes it thru the Intercooler into the airbox. The pres-
sure in the airbox is controlled by the Throttle. From the airbox
the compressed air moves thru the intake manifolds into the
four cylinders.
Figure 11
The compression rate of air is depending on the amount of ex-
haust gases passing the compression side of the turbocharger.
For controlling this compression rate the waste gate has an im-
portant role. If the wastegate is fully closed the complete flow of
exhaust gases must pass the turbine. The more the wastegate
is opened, the less exhaust gases have to pass the turbine.
The waste gate is powered by the boost pressure from the com-
pressor. Pneumatic valves actuated by the ECU control the
amount of the boost pressure necessary to adjust the waste
gate to reach the requested boost pressure. The PCV, as well
as Wastegate, are normally closed
In case of overboost conditions the overboost valve is opened
to relieve the excessive pressure.
The two Ambient Air Pressure and Temperature Sensors
(AAPTS) are all-in-one sensors for engine ambient temperature
and engine ambient pressure. In cowled engine installations
they have to be mounted in the engine compartment in a ram
air free area and close to the air inlet. The sensors must
BRP-Rotax Effectivity: 915 i A Series
Edition 0 / Rev. 0