And that is what I think. Take out the forces on the crank that are unbalanced parasitic and harmonic loads. Seems like compressive force from the cylinders transmitted to the crank are known,. but centrifugal forces due to poorly balanced rotating assembly at high RPM are huge. I seem to remember steel is very strong with regard to compressive strength, but comparatively weak with tensile loads. I am not an engineer, but it seems that is what I have read. I had a PhD structural engineer tell me one time, "try it, and see if it breaks"!