Ray McCrary wrote:
>
> What I heard was that the Boys in Belgium were going to allow the Brits
> only a mule to ride into London.
> Less airborne emissions and full employment for the crossing sweepers! Ray
>
> At 09:33 PM 12/6/97 +0000, Paul Hunt wrote:
> >... Leaving thousands of asthmatics dying in their wake.
> >
> >And what's this we UK-ers hear about Minivans and Cherokee-type vehicles
> being
> >classed in the USA as small trucks and allowed to pump out 50% more
> emissions than
> >cars?
> >
> >PaulH.
> >
> >Ray McCrary wrote:
> >>
> >> Actually, the new high speed diesels that are now in the cars and light
> >> trucks not only run at comparable speeds, but last a very long time indeed.
> >> Most of these engines are quite small.
> >> Ray
> >>
> >> At 09:54 PM 11/29/97 -0500, Mere wrote:
> >> >Hello Peter and List:
> >> >
> >> >I must take exception to this "diesel engine thinking" regarding wear on
> >> >engines. Yes, starting places offers wear opportunities on engines but an
> >> >engine with good oil and decent oil pressure will not wear unduly at
> >> >startup. However, the idea that engine life will be enhanced by
> leaving it
> >> >running is questionable.
> >> >
> >> >I believe, as others have stated, that there are only so many revolutions
> >> >in the life of an engine. Leaving it idling for lengthy periods does not
> >> >allow efficient running as idle mixtures are the least efficient in
> >> >carbureted engines which will add greater products of combustion to the
> >> >oil, and contribute to poor temperature differential within the engine.
> In
> >> >cold weather, an idling engine will actually cool off if the car heater is
> >> >left on. As manufacturers have recognized, one of the most important ways
> >> >of avoiding wear is to drive the car as soon as possible after cold starts
> >> >so that the warmup is not prolonged. The sooner it is warmed the less
> wear
> >> >can occur.
> >> >
> >> >A cold engine has larger clearances than a warm engine and cold oil has
> >> >higher viscosity than warm oil. Thus the cold oil in the cold engine will
> >> >stick better to vertical surfaces and will fill larger engine clearances
> >> >better than hot oil. As the oil and engine warm the clearances
> decrease as
> >> >viscosity declines. The real culprit in startup is cylinder wear but
> >> >proper oil and pressure reduces this problem almost instantaneously.
> >> >
> >> >What determines cylinder wear is the simply the number of times the piston
> >> >travels up and down in the bore. Every one of those cycles causes wear.
> >> >Why does a large displacement V8 engine seriously outlive a small
> >> >displacement four cylinder engine? It does less work at much fewer RPM.
> >> >
> >> >It is not at all unusual for a small-block Chev or Ford taxicab to
> >> >accumulate over a million kilometers in service. This is possible because
> >> >of two things. It is started less often and it does less work because of
> >> >its large displacement and lower revs.
> >> >
> >> >Diesel engines however thrive on steady running and don't like to be shut
> >> >off because of problems inherent with compression ignition and proper
> >> >mixture control. Diesel trucks go for millions of miles, not so much
> >> >because they are diesels but because they run at very low RPM and have
> very
> >> >large displacements. If diesels ran at the speeds of our LBCs they
> >> >wouldn't last much longer relative to the work they do.
> >> >
> >> >John McEwen
> >
> >
> >You've got to be a donkey to work there anyway.
PaulH.
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