<VV> Too Much Oil In Engine?

[Mark Durham]

Roy, yes, to a point on the flow, but flow is actually determined by
pressure and clearances.

I know that once flow is maxed out, pressure builds up to a point in
the bearings to their design, and then the extra oil is bypassed by
the relief which is set to open once that boundary pressure is
reached.

Will flow be higher at 35 PSI versus 25 PSI? Yes, it will. The
dymnamics of an engine seem different, but its the same as doing an
experiment with a hose and a fixed nozzle (which nozzle orofice
represents all the oil orfices in the engine) Add pressure, and more
flows to a point, then more pressure makes progressively less
difference in flow. Throw in a pressure relief, and the flow at that
pressure is pretty steady regardless of how much oil is pumped by the
pump, it goes back to the sump via the relief valve while you are
driving down the road at 2500, 3000 or whatever RPM you have above
idle.  As a engine wears, it takes more flow to reach the boundary
pressure to the relief opening, and at the end of its life the pump
may not have enough volume potential to make the oil pressure where
the relief will not open at all and extra wear accelerates.

When the pump is at idle, there may not be enough flow to keep it at
the bypass PSI, so pressure drops. Not that that matters too much, it
does not take much pressure to maintain the boundary layer of oil in
the bearing when there is no power trying to break down the oil
barrier. That is also where the ZDDP comes in handy, since it is
burnished into the metal surfaces when ever a rub happens, then wears
at the next rub, that is why ZDDP is so critical for cam life, less so
for bearings, but it plays a part there for startups, etc. Mark Durham

On Wed, Feb 16, 2011 at 6:01 PM,  <rbuckridge at comcast.net> wrote:
> OK, so they are built differently.
>
> I think the point is, at rest you set the oil level. Once the engine starts
> the oil level drops as it circulates thru the engine. As rpm increases,
> doesn't the oil get pumped even faster?
>
> A shop teacher had us calculate the oil pump out put at 5,000 rpm. I don't
> have figures in front of me, but that may be an interesting exercise.
>
> Roy @ exit 77
>
>
>
> ------ Original Message -----
> From: "Mark Durham" <62vair at gmail.com>
> To: rbuckridge at comcast.net
> Cc: "Virtual Vairs" <virtualvairs at corvair.org>
> Sent: Wednesday, February 16, 2011 4:36:51 PM
> Subject: Re: <VV> Too Much Oil In Engine?
>
> Yes, but those engines are built different.
> Mark Durham
>
> On Tue, Feb 15, 2011 at 9:05 PM,  <rbuckridge at comcast.net> wrote:
>>
>>
>> If the oil level is a little over, I wouldn't worry about it.
>>
>> Seems to me, Chevrolet recommends Corvette owners add an extra quart of
>> oil when doing track day events.
>>
>> Roy - Bayshore
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