page 48
May 01/2007
Effectivity: 912 Series
Edition 1 / Rev. 0
d04054
INSTALLATION MANUAL
BRP-Rotax
12.2) Operating Limits
Using conventional coolant:
Coolant temperature: (coolant exit temperature)
max.........................................................120 °C (248 °F)
Cylinder head temperature:
ROTAX 912 UL/A/F:
max...................................................150 °C (300 °F)
ROTAX 912 ULS/S:
max...................................................135 °C (275 °F)
Permanent monitoring of coolant temperature and cylinder head temperature
is necessary.
Using waterless coolant:
Cylinder head temperature:
ROTAX 912 UL/A/F:
max...................................................150 °C (300 °F)
ROTAX 912 ULS/S:
max...................................................135 °C (275 °F)
Permanent monitoring of cylinder head temperature is necessary.
Additional monitoring of the actual coolant temperature is possible but not
necessary for waterless coolant.
▲
WARNING:
The cooling system has to be designed so that operating
temperatures will not be more than the maximum values.
Monitoring the cylinder head temperature is important to control the engine
cooling and prevents detonation within the operating limits. It is also necessary
to design the cooling circuit so that under no conditions the coolant does get near
its boiling point, because a subsequent loss of coolant can quickly cause the
engine to overheat.
The boiling point of the coolant is influenced mainly by:
-
the type of coolant
-
the proportion of the mixture (percentage water rate)
-
the system pressure (opening pressure of radiator cap)
Correlation between coolant temperature and cylinder head temperature
There is in principle a regular relationship between coolant temperature and
cylinder head temperature. The coolant transfers some of the combustion heat
to the radiator. Thus, the coolant temperature is usually lower than the cylinder
head temperature. But the temperature difference between coolant and cylinder
head is not constant and can vary with different engine installation (cowling or
free installation, tractor or pusher, flight speed, etc.).
