Jerome, thanks for your interesting high caliber remarks re. my PSI report.
You are unusual in that by being in a tech. business (and obviously having
an engineering background) you were able to understand all my remarks properly.
I am a bit dissappointed to see joking remarks from Jarrid in which he uses
imaginary terms like "..massive oil theorem" ," bearingus collingus",
"heata da oilipus nogeta nada backipus", race engine fluid seepage" etc.
Any sort of reply which uses heavy humor mixed with serious technical facts
tends to weaken the story and can lead to reader to think that the original
text may also have been a joke. I enjoy a good joke as well as the next
guy , but don't usually mix them into tech talk.
Contrary to one reply, liquids cannot be compressed ! (at least NOT in auto
engines). Also, the act of pumping oil through an engine oil pump does NOT
meaasurably increase the temp of that oil. Un-needed extra pump volume is
dumped off via the by-pass and regulator devices and this allows the pump
to keep full of moving oil at all times.
This gear type oil pump is different from diaphragm type fuel pumps, in
which the fuel actually comes to a halt when the carb has had enough.
The reason why an oil pump system is able to keep a positive pressure in
the main gallery where we read it on Rootes engines, is because our "gear
type" pump is a positive displacement pump. This means that its output is
essentually linear in nature.
If spun at say 1000 rpm it makes 10 gal per minute.
If spun at say 2000 rpm it makes 20 gal per minute.
(these are not true figures for the Rootes pump and the linear action is
unable to be sustained when a certain high rpm is reached and the holes and
port flows reach their limits)
Engineers select a pump output figure according to the engine bearing areas
and design clearences. A three main four cyl engine may need a pump having
say 6 gal per minute at 1000 rpm.
A five main V8 may need a pump capable of say 12 gal per minute at 1000 rpm.
There are MANY other variables and conditions which engineers have to
consider in this selection process.
The bottom line though....is to maintain the hydranamic wedge of oil in
every plain bearing and this is done by assuring ample volume flow through
that bearing.
------------------
Yes...race engines do use very high output pumps and 60 psi is not unusual.
Such high pressures result in EXCESSIVE oil volume through the bearings.
You might now ask...whats the harm in that???!
The answer is....all filtered oil contains microscopic impurities too fine
for the filter to trap!
When this lovely clean, new oil is blasted through bearings, continually,
mile after mile, hour after hours, the velocity at which the oil moves
through the bearing shell has the same affect as a sand blaster or a placer
mining water blast. These impurities simply cause rapid abnormal wear on
the bearings.
Of course a race engine is rebuilt frquently, so this never becomes a
problem in a race car.
Also...there is concern over "laminar flow" which occurs in all hydraulic
pumping systems. Simply put, "laminar flow" and boundary layer affect is a
situation where the layers of oil molecules which lay right against the
metal surfaces, do NOT move, or do not move fast.
Localized hot spots result and bearing failure results.
Engineers push enough oil through a bearing (volume) to maintain the
hydranamic wedge at all speeds and loads. A certain amount of excess
volume is designed into the system as a safety factor (read: dumpped out of
the bypass valve) but serious over-pressure and over volume is not allowed
nor desired .
My original report stated that you the reader would be able to better
understand the PSI subject and reach your own conclusions for personal
actions as related to your own vehicles. I am NOT going to get into any
sort of arguments or defense of this material so this is my last reply on
this subject (unless erroneous statements are seen posted).
Dick T.
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