Installation & Operation Manual
O-360 and IO-360 Series Engines
8 Chapter 3 • Aircraft / Engine
© March 2004 Superior Air Parts Inc. Integration Considerations
C. Oil Heat Rejection
Engine oil is the other primary means of cooling
the engine. Cooling of the engine oil occurs
partly through heat transfer through the walls of
the crankcase and oil sump and partly through a
supplemental oil cooler. Supplemental oil
coolers are oil to air heat exchanger designs and
draw cooling air from the upper cowl plenum
area as discussed previously.
Oil heat rejection requirements for Superior
Vantage Engines are defined in Table 4 of the
Model Specification Data. Superior Air Parts
recommends that the oil cooler be sized to
provide at least 150% of the required maximum
heat transfer to provide an adequate margin of
safety.
The reduction in temperature and density of the
ambient air with increasing altitude can
significantly effect the performance of the oil
cooler and sizing should be chosen accordingly.
Although the reduced temperature of the air can
increase the efficiency of the cooler due to a
larger temperature difference between the hot oil
and the cooling air, the reduced air density is
generally a larger consideration and will result in
an overall reduction in cooler efficiency at higher
altitudes. Therefore, cooler sizing calculations
should be made with the air density appropriate
for the maximum intended altitudes of the
installation.
D. Accessory Cooling
Typically, engine cowl baffles effectively
separate the upper cowl plenum from the lower
cowl plenum through the axes of the cylinders.
However, the rear cowl baffle is typically
attached to the engine crankcase and therefore
most engine accessories are “behind” the rear
cowl baffle or below the cylinder axes and
therefore part of the “lower” cowl plenum.
Unless otherwise provided, these accessories
are located in an area of relatively stagnant air
that has already passed over the engine for
airside cooling or has passed through the oil
cooler. Because of the elevated temperature of
the air surrounding these accessories and the
relative lack of airflow around them, it is often
necessary to add small, supplementary ducts to
provide cooling air. The amount of
supplementary cooling required for these engine
accessories is installation specific and must be
determined by testing. Temperature limits for
these accessories are specified in the Model
Specification Data
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