Flyin' Miata : Technical information : High volume oil pump

Here's a comparison of a stock Miata oil pump and a commercially available "high volume" (HV) pump. The HV pump has a Ford part number with an identical casting and gear size. The gears are interchangeable. The relief valve is the same and there was no measurable change in oil pressure when the pump was installed in one of our engines. The seller gave some questionable technical reasons as to why it's high volume - such as better bearings, but there are no bearings in an oil pump - but we see no differences. However, they are a good price if you're looking for a stock pump. Thanks to Bill Wilner for supplying the HV pump for investigation.

We are considering having some deeper and stronger gears made along with harder relief valves for a true high volume oil pump.

The two pumps side by side. The HV pump is on the left.
The front side of the two pumps.
A closeup of the HV pump.