Re: Lugging engines - aren't they suppose to lug themselves?

[<ChrisBourk@xxxxxxx>]

Again we have so many people saying so many things (wasn't that a song?).
Running the engine at minimum operating speed is not bad for it and the engine
will generally last longer not shorter if this is done.

Because:

1. Stepping on the gas more DOES NOT give the engine more fuel unless the
RPM's increase. The DME looks at air flow, water temp, engine speed and
determines fuel flow.  Stepping further on the gas allows more air in IF the
thottle plate is the limiting factor - if it isn't NO MORE AIR (basically)

2. Lugging the engine increases the thermal efficiency of the engine, the BMEF
(back mean effective presure) in the cylinder goes up. [Just like turbo
charging :)]

3.Oil presure: BMW in their wisdom (I would hope) calculated the maximum
bearing load at any given RPM and backed into what the oil pump needed to do
for that bearing load.  (Why is it that so many people seem to think BMW has
never thinks about this stuff?) Botton line: The loads on the bearings just
ain't that great at low speed and at low power to hurt them,

3. Running at engine speeds over the minimum power it takes to move the car
wears the engine out faster.  Engine wear is no were near Linear. The engine
doesn't wear out twice as fast at 6,000 RPM as it does at 3,000 it wears out
much much much more than twice as fast.

4. The above does not address the issue of harmonics (critical speeds at which
the natural imbalances of the engine compliment each other) these speeds
should be avoided as wear increases rapidly in these ranges.  Remember,
imbalance goes up as the square of the speed - twice the speed 4 times the
effect of the imbalance.

I consider "lugging" to be operating out of "Bimerspace" not at such a low
engine speeds that the car bucks and stalls - this is of coarse abuse.

For purposes of the above, "Bimerspace" is defined as any engine speed at
which you're paying more attention to the radio or the conversation of people
in the car than you are to the sound of the engine - if you're lisening to the
radio or talking to peple in the car, you are hereby and herewith declared to
be lugging your engine :)

Christopher
///M635CSi
E-28 535 
Only lugs in sight are on the wheels...

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