Um have you ever heard of this wonderful invention called a bearing?
there really great, you see they can be used to mount a rotating component into a fixed component and they eliminate transmission of rotational forces from on to the other
Not guna argue any more chap but can I suggest that you go away and read a physics book or go and ask someone who knows what they are actually talking about!
I did! You should try it sometime

When you rev your engine it rocks on its mounts yes?, this is because the torque reaction makes the block rotate in the opposite direction to that of the crank yes?
But in order for it to twist the block like you are suggesting one end of the crank would need to be accelerating faster hence creating more torque or even rotating in the opposite direction than the other end.
Its the same as if you held a small cardboard box in both hands.
If you twist your hands in different directions it will subject the box to torsional stress, but if you twist your hands in the same direction the box still twists (just like an engine block) but both ends are twisting at the same rate, hence the block its self is not being subjected to torsional stress!


If your theory was correct then how come your diff casing doesn’t split every time you dump the clutch? I mean you’ve got the prop and drive shafts spinning around inside it, surely that’s guna twist the hell out of it! lol.

if you need more info i will give you the email address of some lecturers on my course who im sure would be more than happy to explain this to you! lol.