Re: Lugging

[Robert T Chafin <rtchafin@xxxxxxxxxxxxxx>]

Bruce writes:
>Lugging: Operating an engine below its "normal" range under load, so that it
>demonstrates general signs of discomfort through noise, vibration,
>harshness, and a general unwillingness to accelerate the vehicle in an
>acceptable manner.
>
>(Insert picture and sound track here of any Corvette in sixth gear at 30
>mph, trying to accelerate up a hill.)
>
>Lugging is supposed to be "bad" for your engine. For purposes of
>conversation (and short of prolonged detonation in a vehicle without knock
>sensors), I say that it isn't - it's only bad for your teeth and jaw muscles
>if you are in the vehicle.
>
>Prove me wrong.
>
>No fair saying "It'll burn your valves!" or some such, unless you're willing
>to describe just why and how lugging does this, or any other bad thing.
>
>Nyah Nyah, Nyah Nyah Nyah! Betcha can't prove it's bad!
>
>(Just a friendly topic from your ol' Uncle Brucie) 

Sorry Bruce,  I'm writing to agree with you that there's nothing wrong with
'lugging' an engine;  the objectionable vibrations that most people think
is the engine objecting to being run too slow is a combination of clutch
torsional vibrations, and for carbureted engines, poor combustion due to
poor mixing/poor air-fuel distribution. Clutch torsionals are 'tuned' out
by adjusting driven plate damper springs to suit flywheel and driveline
masses, or in some cases by using 'bifilar' flywheels.  Mixture variation
problems are largely a thing of the past with injected cars (or rather,
injected engines) since the fuel is injected near the intake valve, and has
relatively little chance to drop out on the port walls.  
In fact, from a fuel efficiency standpoint, lugging is probably one of your
most efficient operating modes, since you can run at or near wide open
throttle (the technical term is 'WFOT';  the poor slobs at the EPA
honest-to-God think the 'F' stands for 'Fully'!) and thus don't have the
losses associated with pressure drop across the throttle plate(s).
Robert

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