T1 Race and Development - GT1R Oil Filter Adapter for Nissan GTR R35 VR38
The OE Nissan and equivalent size oil filters are designed for light weight oil, OE spec is 0w40. As the viscosity increases, which is common in high-performance rebuilds (GT1R Engines are spec'd for 20w50 Oil), the factory filter begins to become a restriction to the thicker oil.
Most filters have a bypass that opens around 10psi differential oil pressure. What this means is when the pressure on the inlet side of the filter becomes 10psi higher than the pressure on the outlet side of the filter, the bypass opens and you get unfiltered oil passing into the engine. This is bad for obvious reasons.
The WIX Racing filters are designed for thicker racing oils and higher oil flow rates (which comes with increased RPM). While their filtration spec isn't quite as good, ~60 micron vs ~ 35 micron, all of your oil is being filtered. 60 micron is better than no filtration! The Racing filter flows 28gpm, where the XP version flows 9-11gpm.
The increased surface area, and increased flow capability of the racing filters ensures less pressure drop across the filter (which equals more oil pressure at the engine), and in the case of the recommended 51060R WIX Racing filter, there is no bypass, so 100% of the oil is filtered 100% of the time.
For those that do more street driving than track driving, the WIX 51060XP filter is a good option. The higher than average bypass setting of 15psi, and increased surface area, will result in little if any bypass as long as the filter is in good condition, as flow will reduce as the filter gains contaminants stored.
The GT1R Oil Filter adaptor includes the conversion base, threaded filter boss adaptor, and a WIX oil filter of your choice. The threaded filter adaptor is female on the OE side, and has a retaining clip to keep it together with the conversion base. Once installed, the base and threaded adaptor will remain on the engine during oil changes, making it a simple on/off filter change for oil changes.