Quote:

Race engines with bigger clearences need more volume. Oil systems is not a place to gamble or skimp on.



I agree, enlarging clearances will require more volume of flow to maintain the same pressure, all other things being more or less equal. But, that doesn't automatically mean a standard pump won't work, it may or may not, depending on the exact factors involved which primarily amount to pump capacity and the flow needed to have sufficient pressure with given clearances. If the pressure is adequate, which indicates the flow is also adequate for that combination, then installing a larger pump will just bypass more oil assuming the pressures are equal.

Let's compare this to flow bench principles. The flow bench is adjusted to maintain the same pressure as the test is repeated at various valve lifts. When a port flows more air, you increase the volume of air being pulled (or pushed) through it until the pressure equals the standard you are using. Having a means to regulate pressure (a bypass or return) allows pumps to work over a certain range of flows. So, as long as a flow bench is capable of pumping enough air to reach the desired test pressure a large bench (pump) will not gain anything as you just bypass or regulate the flow downward to keep the pressure in check.

My 2 cents on the oil pumps is a bigger (within reason) pump is better than one too small, but it isn’t better than one that is smaller but big enough.