rod journal size vs rpm

[Ed Wright]

Originally Posted by Everett Hill

all the small block fords are steel which one stock or after market,I have turned mine 10,000 at times mostly 9,000 to 9,500

Wasn’t the question originally about crank journal diameter versus RPM?
That is about the surface speed of the bearing against the crank. Smaller crank journal diameter reduced the speed of the bearing against the surface of the crank.
Of course, you can usually get by with high surface speeds. Lower speeds improve reliability. “Honda rods” did not make mine any faster, but did reduce bearing wear.
Your results may vary.