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PORTS AND FITTINGS
The fuel rail ports are tapped for 8AN ORB.
8AN ORB Adapter Fittings can be found HERE.
8AN ORB Fuel Pulse Dampers can be found HERE.
Fuel Pressure Gauge Adapters can be found HERE.
Appropriate fittings must be selected based on the specific application. Ample space around the fuel rail port(s) is necessary for larger accessories such as fuel pressure regulators, fuel pressure gauges, and fuel pulse dampers. To verify clearance, the dimensional drawings on the product pages can be used as a reference guide.
These Radium Engineering fuel rails are compatible with the VR38DETT engine found in the Nissan R35 GT-R. They are machined from 6061 aluminum and anodized black for compatibility with all popular fuel types including E85. Manufactured with a large internal bore, the fuel rail can support all necessary engine power requirements. Each rail has four 8AN ORB ports (2 end ports and 2 top ports for a total of 8 ports). The fuel rail features 14mm injector bores and is compatible with the OEM injectors and any aftermarket injectors with OEM VR38DETT fitment.
The fuel rails mount with insulating spacers and washers for 100% fuel insulation from the hot intake manifold. The unique lower intake manifold mounting points permit shorter less restrictive rails. Additionally, the OEM injector clips can be reused, as shown below.
With 4 ports on each rail (8 total), it is easy to add fuel system accessories such as a pressure transducer, fuel pulse dampers, etc. There is also opportunity to plumb the fuel rails in parallel or series.
As shown below, the base kit (P/N: 20-0556-02) includes ONLY the fuel rails and associated mounting hardware. NO FITTINGS ARE INCLUDED.
OPTIONS
PLUMBING KIT
20-0556-PK Fuel Rail Plumbing, Nissan R35 GT-R
When used with the 20-0556-02 fuel rails, this kit permits a bolt-on, plug and play affair. 
A stainless steel mount if provided for the Radium FPR. Low profile 90 degree SAE adapters with PTFE fuel hoses connect the OEM hard fuel lines to the FPR. PTFE fuel lines run from the FPR to the rear fuel rail ports. Two Radium fuel pulse dampers and a pressure gauge are included and all necessary adapter fittings. 
OEM FPD ADAPTER
20-0459 FPD Adapter, 8AN ORB, 27mm Bore
The OEM VR38DETT fuel pulse damper can be reused with this adapter. These can install into any fuel rail port provided there is adequate clearance.
NOTE: If the 20-0556-PK plumbing kit (listed above) was purchased, this adapter can be used in the spare top port, as shown below.