Given that the pumps are positive displacement (I assume), there should be a fixed flow at a given speed. Pressure will vary based on the system resistance to that flow, and then the relief valve will control to a set pressure. I guess what I'm looking for is an idea of the minimum flow necessary for adequate lubrication for rotating the engine.
My purpose in looking for this info is I want to size a gear pump to act as a pre-oiler (I know there are already commercial pre-oilers out there, but I just want to size a pump to do a periodic oiling of an engine not in use and don't want to buy a whole airworthy system).
I guess I could just buy a cheap gear pump, hook it up, and see if it makes pressure when run by a drill motor or similar. Don't want to waste money buying a pump that's too small.