Lawrence, you ask for source materials which may help support the
statements and various bearing problems recited in my original message.
I would call the 800 number for TRW Corp as they have presented many SAE
papers on this bearing subject. Of course there are many other bearing
makers so you can contact many more.
I would suggest contacting the Director of engine engineering at the GM
tech center in MI. Don't know who he is these days but this can be
determined and the operators will provide the numbers.
Finally, I would call up Shell, Mobil, Std Oil etc. and ask about bearing
wear problems as related to hyper velocity oil flows, laminar flow problems
and any other related subjects.
While speaking to any of the oil co's be sure to ask about Viscosity Index
(VI) numbers and how this relates to oil film strength and resistence to
penetration of the hydranamic wedge when VI fails to stand up.
The interesting thing about VI (which has no relation to oil viscosity) is
that Pennsylvania crude has the highest natural number ( about 114 I
recall?) and when they refine it they have to purchase and add the "least"
amount of VI-Improvers, which are expensive.
The Penn. oils could technically be sold cheaper than any other oil in the
world because it costs less to make the finished product.
Does this happen????? hell no ! Quaker State, Pennzoil and other Penn. base
oils always are amongst the highest in cost to the public because they hype
their name for 90 years. The lower grade crude oils, like Mid-continent,
LaBrea, Gulf grade etc. are quite a bit more costly to mfr. due to more
additives being needed in order to meet the the SAE and API specs.
Fact is, that all SH rated oils must and do perform the same! Throughout
the years that the API has provided their ratings, this equality has been true.
-------------
You mentioned the query re. why laminar flow or boundary layer stagnation
would result in bearings getting overheated. I am NOT able to discuss this
in proper depth as it is not something I have studied. However, as it was
explained to me, the reason is simply that when molecular oil layers don't
move much, they absorb lots of heat from the engine metal and do not
effectively transfer this heat into the moving layers of oil.
I sort of visualize a pot of thick soup on a hot burner. If the spoon
fails to get down low enough to churn the very bottom of this soup, we will
have some burned soup at the bottom where stagnation existed. This same
principal or theory results in poor heat removal from the bearing, with
eventual short life or failure. Also...engineers have been paying great
attention to "preventing" engine oil from being charred or overheated due
to impinging on really hot engine metal. Some earlier V type engines let
the oil contact the underside of the manifold heat cross-over under the
carb area. This constant charring of course shortened oil life.
Since about the early 70s this is no longer allowed and the oil lives
nicely for high mileage and time durations. This is reflected in higher oil
change reccommendations in owners manuals etc.
Of course the oils themselves are so completely superior to what we had
even 10 years ago, it boggles my mind to look back upon the oils we had
available in the early years of the automobile and other IC engine designs.
WW-2 saw the start of strict oil performance criteria (Mil-Spec Oils) and
the industry has been running in high gear ever since !
Thats about all I know and I'm certain the LIST will enjoy seeing some
report telling about what you might be able to turn up on your own.
Dick T.
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