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Old October 9th 04, 08:18 PM
Bill Putney
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John Kunkel wrote:

> "Bill Putney" > wrote in message
> ...
>
>>John Kunkel wrote:
>>
>>>"Daniel J. Stern" > wrote in message
ngin.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.


Ah! I didn't realize you were talking about varying the engine speed by
changing the gear ratio.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')


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