I don,t think you are comparing apples to apples.
The suction side works differently than the output side.
I thought that drilling the passages in the block to half inch was to decrease the pumping losses. It's easier for the pump to push the oil.
It does not mean the leakage rate of the motor will be higher just because we opened the passages up in the block. The bearing clearances would still be the restriction.
The flow rate through the block could still be substantially less than what the passages could free flow.
