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When I say Lugging, I mean high load, low RPMs, at the highest possible load to avoid the engine shaking / struggling. I was using about full throttle between 600 and 1200rpm in 5th gear (!),
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The crankshaft and connecting rod bearings in the engine are just plain bearings. They have no balls or rollers, just a thin metal shell insert with an oil groove which "rubs" against the crankshaft.
Lots of pics, here, look at the half-circle sheet metal looking things.
http://images.google.com/images?hl=e...h+Images&gbv=1
You know how your car tires will hydroplane when you go fast enough thru deep enough water. The bearings work on this hydroplaning principle. If the rotational surface speed of the bearing is fast enough (fast enough engine rpm) the crankshaft will hydroplane up on the oil film and never touch the bearing shell when the engine is running.
Otherwise, it will rub and wear the bearing. You will not know it is wearing for a long time, and then it will be too late and you will hear knocking noises when the engine idles. This noise is caused by the clearance in the bearing getting bigger due to wearing away the bearing shell. At this point people put in thicker oil and sell the car.
I would suggest not using full throttle at very low rpms for this reason. You combine high bearing loads with low bearing surface speeds.
This is also why all those "endurance" tests where a car is driven at 100 MPH for 500 K miles are such horse-pucky. The starter motor gets used once per oil change, the clutch 5 times per gas fillup and oil change, and the bearings in the motor get no wear at all, they are on the oil film almost all the time. And body rust? Forget about it.
