Operating Limits - Rotax 914 series Installation Manual

12.2) Operating Limits

Using conventional coolant:
Coolant temperature: (coolant exit temperature)
max.....................................................120 °C (248 °F)
Cylinder head temperature:
max.....................................................135 °C (275 °F)
Permanent monitoring of coolant temperature and cylinder head temperature is
necessary.
Using waterless coolant:
Cylinder head temperature:
max.....................................................135 °C (275 °F)
Permanent monitoring of cylinder head temperature is necessary.
▲ WARNING: The cooling system has to be designed so that operating temperatures
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.).
Effectivity: 914 Series
Edition 2 / Rev. 0
BRP-Rotax
INSTALLATION MANUAL
will not be more than the maximum values.
page 44
July 01/2008