Radium K-Series Fuel Rail for RSX and EP3 Civic Si, Black

Radium Engineering K-Series Fuel Rail for RSX and EP3 Civic Si, Black - Part #20-0230-02

The factory K-series rail is fine until you want AN plumbing, a pressure sensor in the rail, or a fuel system that isn't built around the OEM quick-connect. Radium's 20-0230-02 is a black anodized extruded aluminum rail with a 0.69 inch bore and three 8AN ORB ports that bolts to the K20A2 and K20A3 intake manifold in the 2002-2006 RSX and 2002-2005 Civic Si, keeps the factory injectors and spacers, and gives you real ports to plumb from.

What It Is and Why It Works

The rail is extruded 6063 aluminum, CNC machined, media blasted, black anodized, and laser etched, with a 0.69 inch internal bore that holds enough fuel volume to keep pressure steady across four injectors at any power the K20 will make. The three 8AN ORB (3/4-16) ports take any ORB adapter, plug, or gauge fitting, so you can feed from either end, run a pulse damper, or thread in a pressure sensor. Injector bores are 14mm, which means factory injectors and any OEM-equivalent aftermarket injector drop in, and the kit reuses the factory plastic injector spacers. Phenolic washers under the mounting feet insulate the rail from the hot intake manifold, which matters on a K-series where the rail sits right on top of the plenum. Stainless mounting hardware is in the box. Fittings are not; the rail-only kit is for custom plumbing, and Radium's 20-0230-PK plumbing kit adds the extended SAE quick-connect fitting and port plugs to connect the factory feed line.

Specs

Fitment

Also fits a K20A2, K20A3, or K20Z1 swap running its factory intake manifold. Radium lists the RSX and EP3; if you're on an RBC or other K24 manifold, confirm the rail mounting pattern before ordering.

What to Know Before You Buy

Decide how you're plumbing it before you check out. For the factory feed line, buy the 20-0230-PK plumbing kit with it; its extended quick-connect is what clears the coolant hose on the RSX. For AN lines, you need two 8AN ORB adapters and a plug, or two adapters and a gauge fitting in the third port. Oil the ORB O-rings, torque the rail bolts evenly so the phenolic washers seat flat, and check injector O-rings for nicks on the way in; a 14mm bore is tighter than it looks. If you're upgrading injectors at the same time, confirm the injector length is OEM-equivalent; Radium can't spec beyond that, and a longer body won't seat.