Quote Originally Posted by string View Post
Why would increased power contribute to rod bolt failure? Extra downwards force on the piston doesn't make the bolts work harder to hold the cap on - the force is in the wrong direction.
I don't think that thats the correct way of looking at this though because it isn't just a push pull force but also a rotational force as the rod moves with the crankshaft. The top of the rod supports the piston, "added weight", the rod (and ultimately the bolts) are supporting this load whether the piston is going up or down - and there's never a "straight down" force applied except when the piston is TDC right? The rods are almost always at an angle.