RE: bmw-digest V9 #102

[Thi VanAusdal <tvanausdal@xxxxxxxxxxxxx>]

> Date: Mon, 24 Aug 1998 23:11:35 EDT
> From: <ChrisBourk@domain.elided>
> Subject: Lugging and the effects thereof...
> 
> <<Date: Mon, 24 Aug 1998 17:39:20 -0400
> From: Bruce Augenstein <Bruce.Augenstein@domain.elided>
> Subject: Flame Summary: Lugging>>
> 
> <<As the pistons stop at the top and bottom of every stroke and move
> slowly
> near TDC and BDC, dropping the engine speed increases the distance the
> rings
> travel with questionable lubrication film formation.  The same logic
> applies
> to the side loads on the pistons, except that these peak halfway
> through the
> stroke.">>
> 
> Oh,  and I thought that when you decreased speed you REDUCED the
> distance
> traveled....oh well,  live and learn...
> 
> But I thought the speed increased under your theory?   Well now I can
> see it
> certainly makes sense to increase speed when the lubricating system is
> having
> trouble - I'd never really thought of it that way...
> 
Bruce said: by slowing down the engine, the oiling of the upper cylinder
walls decreases.  
Therefore, the rings travel further in poorly-oiled walls than at higher
rpms, when more oil 
is splashed up.

> <<In any event, it is my personal opinion that lugging is extremely
> bad for
> your teeth and jaw muscles (at least it is to mine), and, in fact, may
> lead
> to at least as much cylinder wear as running to red line does. That is
> to
> say, habitual lugging may cause as much "damage" as habitual flat out
> driving does. Occasional lugging is probably just as safe as
> occasional red
> lining.>>
> 
> Great opinion,  just lacks any support.  Go to ANY race track in the
> world and
> ask when engines blow up, when valves sink, when bearings spin, when
> rods
> snap, when cranks break, when rods pull the piston boss right out of
> the
> botton of the piston, when cams break, when valve springs snap, when
> balancers
> fly off - ask them and you will see it happens at speed.  not when
> they're
> lugging their engine - but when they miss a shift, shift into a lower
> gear by
> accident, have too much boost, make too much power.  My boy this
> happens at
> speed - NOT when they're lugging their engines.
> 
> <<On the other hand, even though my 3 liter M3 will pull away smoothly
> from a
> thousand rpm in fifth (if I'm gentle), it's a bunch happier when it's
> at
> 3500 or more, and so am I :-).>>
> 
> Hmm,  now thet's science.  An engine being discribed as "happy" 
> 
> I did kind of like the idea of the cylinder wear,  problem is it never
> gave
> any numbers or science to back it up - just a hunch and by who?  And
> all the
> people who think your engine dosn't have "metal to metal contact"
> NOT,  they
> all do,  oil is a step in the right direction but if there was no
> contact the
> wear would be considerably less
> Best regards,
> 
> Christopher
> 
Go to ANY race track in the world and show me when they lug their
engines.  I thought
the point of racing was to finish first, and YOU MUST KEEP THE ENGINE IN
ITS TORQUE
BAND to do that.  So unless they're running DC (not Duane Collie!)
electric motors, peak
torque is simply not available off idle.    Furthermore, you're talking
extremes here.  Race motor
design in higher classes (non-stock motors) goes for lighter and
stronger components.  There
is a point of diminishing returns with respect to longevity, and racers
are willing to push the
limits of metallurgy, the rules, and themselves to take home that
checkered flag.  The type of
engine service is entirely different than any street car (named Desire?)
should ever see.

I agree with Mr. Eyestone's(*) gut feeling that occasional lugging and
occasional redline runs
are not significantly detrimental to the life of your motor, and
certainly entertain his ideas more
than some sarcastic banter.  

This wasn't a flame topic until someone got sarcastic.

 - thi v.

(*) A little fun with Bruce's Teutonic last name.

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