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Old October 9th 04, 05:46 PM
John Kunkel
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"Bill Putney" > wrote in message
...
> John Kunkel wrote:
> > "Daniel J. Stern" > wrote in message
> > n.umich.edu...
> >
> >>On Thu, 7 Oct 2004, John Kunkel wrote:
> >>
> >>
> >>>>The engine speed is not connected with the oil consumption. If your
> >>>>engine "consumed" (or lost) 4 quarts of oil in 800 miles, you either
> >>>>have a whipped engine or a large leak.
> >>>
> >>>Disagree, many vans had ridiculously low axle ratios and the absence of
> >>>OD would have the motor running at 3500+ rpm's at freeway speeds. A
> >>>tired motor will suck more oil at 3500 than it will at 1800.
> >>
> >>...and a non-tired engine will use no more oil at 3500 than at 1800.

> >
> >
> > Blanket statements like "The engine speed is not connected with the oil
> > consumption." invite disagreement.
> > If the engine consumes a certain quantity of oil on each full combustion
> > cycle, the consumption will increase with engine speed simply because

there
> > are more cycles per minute.

>
> Going with what you just said, that would mean that oil consumption on a
> given engine would be the same amount per mile regardless of speed. IOW
> - if you make a 400 mile trip on straight and level hiway, you might
> make it in 10 hours or in 5 hours depending on whether you drove 40 or
> 80 mph. But, from your statement, you would use the exact same amount
> of oil for that 400 mile trip (i.e., oil consumption would be have the
> same per thousnad mile rate). Not saying I agree or disagree with your
> conclusions - just want to be sure you understand the end result of what
> you're saying.


Suppose an engine consumes one microgram of oil on each full combustion
cycle (two revolutions), at 3500 rpm it would consume 1750 micrograms per
minute but at 1800 rpm it would only consume 900 micrograms per minute.
If a given vehicle is geared so that it turns 3500 rpms at a given road
speed it will consume more oil per mile than one geared to turn 1800 rpm at
the same road speed.
Therefore the statement "The engine speed is not connected with the oil
consumption.' is incorrect.


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