Hi volume oil pump vs standard volume pump

As a guess.. maybe 1 HP. Easy to figure out why:

• The torque/HP needed to turn a positive displacement pump is in proportion to the size. The HV for the SBM has only 20% taller gears than the standard. (That is not a very big increase for an HV, whereas some other HV pumps are 40% taller (and maybe more) than their standard counterparts.)
• So the pump power for the HV is gonna be 20% more pretty much all across all RPM's.
• To see how this works, let's theorize that the difference was 5 HP at high RPM's between HV and standard. For that to be true, then the HV would be pulling 30 HP while the standard would pull 25 HP, so that the 20% difference would be consistent with the 5 HP difference.
• You are not going to be putting 25-30 HP into this size of pump, even at high RPM's LOL.

6 vs 5 HP is plausible. Example computations shows a few HP being drawn by a pump of this size..... though it is hard (for me) to assess the effects of oil viscosity.