Quote:

You have to remember, most of the oil is just pumping against resistance . The amount of oil actually flowing is what all the bleed off clearances in the engine will allow...........




exactly, and people need to get hold of this fact

the milidon pump (according to them and i think they're actually BB ford rotors) is rated at 19-21 GPM of course this is speed dependent but one would have to think that they rated it at a decent speed

these things determine how much oil is actually FLOWING THROUGH the engine

> oil pressure

> clearances (leaks)

> oil viscosity (temperature impacted)

because oil pumps are positive displacement they MUST have a relief system which is the function of the relief spring and valve. any oil that the pump is moving that is not required to maintain the pressure that the relief valve is set at spills from the discharge directly back into the suction. it is simply pumped in circles, the amount of oil pumped by a PD pump is directly proportional to its speed.

oil pumps, hydraulic pumps, roots and screw type blowers are all examples of a positive displacement pump, for each rotation they move an exact amount of fluid.

i have seen PD hydraulic pump bodies literately split in half when they were not protected by a relief valve and someone started the engine with the pump discharge closed.

water pumps, turbochargers, pro chargers are all examples of centrifugal pumps, these type pumps allow for "slip" meaning you can block the discharge and the pump won't lock it will slip.

because of their design centrifugal pumps/compressors are subject to a phenomenon know as surge and i'm not even going to try to explain that and NPSH here