Removed Balancing 'Counter Weights' in Crankshaft?

Dunno...I agree with your observations...
Del

I'm not quite sure what you are trying to say. But adding weight anywhere will not reduce overall mass. The location of the weight will effect it's rotational inertia (resistance to rotational acceleration). If one were to remove the crankshaft counter weight, then it's rotational inertia would be reduced......but at the expense of an unbalanced shaft, which could have disastrous effects.

Automotive engineers have been refining engine parameters for decades so I would venture to say that automobile engines have the lowest mass and least inertia that is safely possible for their designed purpose.

You are right. The overall balance is not so important it is the balance at each journal that matters, otherwise the loads cause the crankshft to bend. A bend in the shaft causes the main bearings to be exposed to additional loads which can lead to their failure. The oscillating loads of an out-of-balnce crackshaft could also result in broken crankshaft or cracked crankcase.

Lightening must be done cautiously as removing weight is also removing strength, both in bending and torsion. Changing the torsional strength of a crankshaft can result in a torsional failure especially if the crankshaft is long (eg. in-line six) and many engines have torsional vibration dampers to control this. You could take this off to save weight but it may come back to bite you. If you change the torsional stiffness of the crankshaft you should really look at changing the torsional damper to suit.

Nice to see bored out journals, the centre of a round bar does not do much for the torsional or bending strength.

Get rid of the counterweights, remove material in non-structural areas, i.e., the counterweight mass. This would have the same effect in balancing the shaft. We can't do this on tires, the next obvious comparison unless you want to start removing rim material each time you put on new rubber.

Cams can't be as easily balanced, but their rotating mass is significantly lower and much closer the the center of gravity and pressure making the overall effort less technical, especially if the production process is more precise.

It's not the weight of the crankshaft that is important but its moment of inertia. The moment of inertia determines how much torque is required to increase its RPM. Take an example: a 1 lb mass 1 ft from the axis of rotation balanced by a 1 lb mass on the opposite side. The moment of inertia is proportional to the mass times the square of the distance. (2x1²=2). If the 1 lb mass were counterbalanced by a 2 lb mass 1/2 ft from the axis of rotation (still balanced), the moment of inertia would be 1x1² + 2x(1/2)²=1.25.

Though it's not by any means technically efficient or cost effective, by making main bearings and crankshaft strong enough you can 'ignore' the per-cylinder imbalance if your most important goal is the lowest possible moment of inertia. But this isn't a modification option on an existing motor. It should be designed from scratch. You'll know when you hear something like that trying to idle at 3500+ rpm. S.M.

Hmmm, not sure what's the point of a low moment of inertia when a huge flywheel is bolted onto the end of it anyway
Del

Also minimized to special clutch size Del. Not aplicable to CatMobile. S.M.

Yep... I was going to forward this question to my friends at "Scat" mentioned above by another poster but I'm afraid they would send me a letter bomb........