At 02:35 PM 5/9/98 -0400, Mike Lishego wrote:
>
>>It seems self-evident to me that (all other things being equal) if the
>>engine doesn't have to turn over as many times per mile while the OD is
>>engaged, it's useful life will be extended. We generally compare engine
>>longevities in terms of miles driven between overhauls. The fewer
>>revolutions the engine turns per mile driven should result in more miles
>>driven between overhauls. Seems like elementary logic to me.
>>
>
> I have heard it said from my Chevy mechanic and I believe, others on
>this list, that only about 20% of engine wear occurs at highway speeds - the
>other 80% occurs at start-up. If this is true, and you were really
>interested in reducing engine wear, your money might be better spent buying
>a kit that pumps oil through the engine before start-up.
Mike,
This is a statistic I've heard before, and based on my understanding
of the internal combustion engine, it sounds very reasonable.
Many engineering facts run contrary to a layman's first order
"self-evident" thought. Not that the logic is wrong, just the
data base. It's the same as "if a bigger carb means more power,
I'll just put a *huge* carb on" or "if airflow is the name of
the game, I'll run a *big* bore exhaust system". Both of these
highly logical statements fail when a deeper analysis is performed
on the function of the engine. The engine has to be able to make
use of the carb. Yes, airflow (CFM) is important, but if you
have exhaust ports the size of a 30 gallon drum you lose charge
velocity.
I'm sure a 'B engine run on a brake, if started only once with a
sump of nice synthetic oil, could probably easily last the equivilant
of 250,000 miles or more at very high RPM. Start and stop that same engine,
and it'd be a different story.
-Keith Wheeler
Team Sanctuary http://www.teamsanctuary.com/
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