A typical Mopar HV rotor is 20 or 25% larger (taller) so on every revolution is going to displace (move) that much more oil. I understand that the bypass spring can come into play as far as demand, I'm sure that's what you're referring to
In a fluid circuit inside the motor you have controlled bleeds (main bearings, rod bearings, valvetrain rocker shafts, lifter galley, etc) which correspond to volume losses and pressure drops which accumulate back into the sump. Increased bearing diameters increase the p losses (controlled bleeds) in the system. There are seriesed (rear to front on a sb crank and front to rear on a BB crank) and parrallel pressure drops along the way. When RPM demands and bleed rates exceed delivered rate of the supply is when you start getting into problems.And in series losses (by definition) the next one in line sees less supply pressure than the one that fed it, so in a way of thinking about it...'adequate' volume and pressure really refers to adequate minimums to the last pieces in line...i.e, furthest from the supply
Porting the passageways (EX: on a SB I always open the #5 main and the pump passage to 1/2") reduces restrictions and pressure drops before the first controlled bleed and porting the pump itself makes it work more efficiently (just like porting the head of an engine) under high demands.
Returning oil to the sump more efficiently is one of the main ways racers can get by with reducing sump volume, thinner oil obviously bleeds back faster as well. Once W2's came out the RPM's went way up and we soon discovered that windage trays on small blocks can cuase issues as they typically didn't have sufficeint baffling to retern oil to the sump...and as a relult oil would puddle in the shelf for the crank to dip the counterwieghts in and became more of a problem than the roping problem they were designed to relieve. We tossed them and our et's dropped.
At least I would only push it that far when trying to set a record. Ron
