>regarding the oil pump, pressure, etc.
Very little oil is needed to actually lubricate the engine internals. In
fact, the clearances at the crucial lube points are fractions of a mil (less
than .001 inch). The hydrodynamic pressures created due to the very small,
localized "pressure" region can be in the hundreds, or even thousands of
psi. You could run an engine with "no flowing oil"....except for the fact
that these high pressures and close clearances, coupled with the dynamic
nature of the pressure variation and clearance changes, mean that you need a
"flow of oil" to carry away the heat generated within this localized area.
Otherwise, the oil, being a hydrocarbon, will degenerate very quickly.
Therefore, an oil sump (the pan) is used to give a dwell time for the oil to
transfer its heat away. The oil pump serves 1 main function: provide the
means to move oil around and thus transfer heat away from the close
clearance regions. A secondary function is to help build up enough pressure
within a close clearance region to (hopefully) ensure the moving surfaces
don't contact during the startup.
This secondary function does not work very well in auto engines because the
engine must be turning quite a few rev's before adequate pressure and oil
flow is built up. So, in cold weather or after very, very long periods of
sitting still, the moving surfaces may make contact and this is when bearing
wear or failure occurs (or, if you don't remove enough heat when running,
then the local temps go way up, the clearances approach zero, the oil
viscosity degrades, the clearance decreases further, etc. and you have
what's called a "self-eating watermelon".
In some industrial equipment, they have a separately powered oil pump that
is turned on before engine or equipment start to build up oil pressure in
the clearances. This helps reduce startup friction, bearing wear, etc.
Roy
'60 TR3a TS63103LO (in restoration)
techman@metrolink.net
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