At high engine speeds or high power levels, your oil pump is subject to damaging vibrations coming through the crankshaft. The gears inside are made of sintered metal, which can withstand about 6 Ksi (6000 psi) of stress before they shatter. Then you lose your oil pressure and very shortly, your engine.
Boundary Engineering has developed 90 Ksi 4140 chromoly steel gears for the Miata oil pump. Yes, that's 15 times stronger than stock. No more shattered gears, no more blown engines!
Pumps are available in various stages. We recommend pairing them with an ATi damper for best protection of your expensive engine.
Stage 1 is a complete pump, assembled with the upgraded gears. They're built to the 1991.5-2000 size and volume using factory housings.
Stage 2 is a complete, high volume pump. The factory housing is machined to accept the deeper VVT gearset, providing high volume and increased oil pressure. The relief valve is also shimmed to raise the maximum oil pressure from 60 psi to 70 psi. This is our favorite option.
Stage 3 takes a Stage 2 pump and adds an upgraded relief valve. Stock valves can sometimes stick, which leads to a loss of oil pressure. The 3 has a hardened steel sleeve pressed in for the relief valve to ensure there's no chance of the valve sticking.
Note that if you have a 1990-91 short nose crank (four-slot front crank pulley and a VIN of 209446 or lower), the only option available is the Stage 2.
You will need a new gasket for the oil pickup. These are usually included with engine rebuild kits, so check to see if you have one already. If not, you'll need to order one separately.