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Nissan Competition Parts
See main article: Competition Oil Pump
Nissan Competition sold a high pressure/high volume oil pump.
Home-made High Volume Pump
Instead of purchasing the Competition high-pressure/high-volume pump, You can make a hybrid high volume oil pump, by using an L-series rotor, which (being thicker) results in extra volume.
Use the L-series engine oil pump rotor and stator, which is exactly the same as A-series parts, but longer. This requires a spacer to make up the difference. It also requires modifying the shaft. Use the larger diameter L-series shaft pressed through the rotor and re-pin it for the A-series gear. Run a 1/2" reamer through the A series housing to make the L-shaft fit.
The stock pump works up to 10,000 RPM, so a special pump is not needed for high RPM use.
But if you run loose tolerances in a race engine, or you run a cross drilled crank with full circle grooved main bearings, then extra volume may well be just what you need. Also modding the rocker shaft for increased oiling requires more volume.
High-volume is more important than high-pressure because it ensures oiling. The NISMO pump uses high-pressure (100psi) and high volume.
High pressure alone will also work up to a point, and is far simpler, only requiring shims on the pressure valve. But the more expensive option -- if needed -- is the high-volume pump. Most built A-series engines do not need either high-pressure nor high-volume pumps.
If your engine is worked hard at high temperatures which results in a measured rise in oil temps, then use an oil cooler to fix the problem. That is much better than simply increasing pressure or volume to compensate.
Donor Pumps
standard high volume * L16/L18/L20B four cylinder * L24/L26/L28 six-cylinder * Z18/Z20/Z22/Z24
highest volume * KA24E/KA24DE * L28 S130 280ZX Turbo
See: A series high volume oil pump
Is High Volume Needed?
Increased pump volume will cut the time it take for oil pressure to come up at start up, especially when using oil coolers that drain back to the sump when the engine is switched off.
Also useful when fitting accessories to an engine which effectively create a leak in the pressure side of the oil system (Example: a turbo - especially the foating bearing type). These will bring the standard pump closer to the point of not being able to maintain good oil presure.
A small volume reserve is good insurance against increased bearing clearances as the engine wears and if a leak occurs (maybe an oil cooler line) oil pressure to the engine bearings is more likely to be maintained (hopefully you realise there is a problem before the sump empties!) Some have reported that the Datsun Competition two stage pump on turbo engine only just has enough presure when the oil is hot and at idle (10 PSI) and that is with a ball bearing turbo that needs a lot less oil than a floating bearing type. But in general the reserve capacity of the standard A series pump has enough capacity to maintain good oil pressure with a turbo and hot oil.
Also, performance motors are generally built with clearances purposely on the large side, thus more leakage of oil when operating and the risk of dropping pressure. Unused capacity from a high volume pump is just returned to the sump via the pressure relief valve. There is extra capacity should you ever need it, but the downside is the extra power required to drive it due to higher pumping losses and thus the load on the cam/engine.
Baffled sump is to help keep the oil in the bottom of the sump even with high G-forces of racing. So a high volume pump is not needed for that.