Radium Port Injection Kit for K20C1 FK8, FL5, Integra Type S

Radium Engineering Port Injection Kit for the K20C1, Civic Type R FK8 and FL5 and Integra Type S - Part #20-0428

The K20C1 is direct injected, and the factory DI pump and injectors run out of fuel somewhere past 400 horsepower, no matter what pump you put in the tank. Bigger DI injectors are expensive and scarce; the answer that works is to add port injection. Radium's PIK is an adapter plate that sits between the head and the intake manifold with four port injector bosses and a fuel rail, so the DI system keeps running as Honda built it and the port injectors add fuel on top under boost.

What It Is and Why It Works

The kit is a machined adapter plate that spaces the manifold off the head by the thickness of an injector boss, with four injector pockets aimed at the intake ports at the angle Radium found sprays cleanly into the runner rather than at a wall. Above it sits a custom rail: extruded 6063, CNC machined, laser etched, 0.63 inch bore, with all four ports tapped 8AN ORB so you can feed from either end and plug or damp the rest. Phenolic spacers and washers isolate the rail from head heat, and OEM Honda gaskets seal the plate on both faces. The rail brackets have two sets of holes for two injector body heights, 34mm and 48mm, with 14mm upper and lower O-rings; that covers the Injector Dynamics ID1050x through ID2600 XDS, Evolved Injection EI and DPI, DeatschWerks 17U and 16U, and RC Engineering SM2 families. It does not replace the DI system; the ECU or a standalone controller runs the port injectors as supplemental fuel.

Specs

Fitment

Radium lists the FK8, FL5, and DE5. All three share the K20C1 head and manifold interface.

What to Know Before You Buy

Budget for the rest of the system before the plate: four port injectors, a fuel feed to the rail (the DI system's low-pressure feed is not sized for it, so most builds run a second pump or a surge tank), hose and ORB fittings, port plugs for the two top rail ports unless you modify the factory harness carrier, an injector harness, and a controller or ECU that can run staged port injection. That's the real cost, and the plate is the cheap part. The injectors have to be 14mm O-ring top feed in one of the two heights; a 60mm injector will not fit. Pull the manifold with the engine cold, and plan on new manifold bolts of the longer length the plate needs. This is a tune-required part; adding fuel without the calibration to use it does nothing.