Warp Speed wrote:
Not sure I agree with that.
Just about every Cup team uses piston guided rods with a box style piston. Where do you get your friction comparison from?
Just a quess. There ain't much friction in rod sides against crank as there is no force between them. Sure thinner rod bearing reduces
friction compared to thicker but thinner rod bearings can used with narrow size clearances:
And very high revving motorcycles don't use piston guiding but very small con rod big end side clearances.
Piston with no skirts in wrist pin sides are con-rod guided in that direction, if there is too much big end side clearance piston will twist in cylinder which sure ain't good for power or piston life.
If engine makes 99,9% it's life at near max rpm it's need for rod guiding is very small as big end's rotating forces will put it perpendicular to small end, as probably is case with those nascar engines. But that won't work with street engines.