Click here to download installation instructions (PDF)
These plumbing kits are designed to compliment Radium Engineering Subaru EJ fuel rail installations. Both kits interface with the factory feed and return hard lines in the engine bay (near the LH strut tower) and provide all the underhood fuel plumbing. Both kits are compatible with all Radium Fuel Rails for the Subaru EJ engines (excluding 20-0499 Fuel Rails). All necessary fittings and hoses are included, along with a RA-Series FPR.
RA-series regulators feature the first tool-less pressure adjustment. A jam nut and set screw are no longer required. With a simple turn of the knob, pressure will be increased or decreased.
To aid in adjusting pressure, there are incremental detents that provide haptic feedback to the user. Every detent permits 1psi (+/-0.5psi) of adjustment depending on current fuel pressure. Furthermore, RA-series regulators feature a 360 degree swiveling vacuum reference port that is double O-ring sealed. This is the first in the industry. It permits the installer to quickly point the vacuum fitting in any direction with no tools required.
There are 4 interchangeable 10-32 threaded vacuum port fittings provided to cover all scenarios.
1. Barbed Fitting: A black zinc-plated 3/16" (5mm) barb machined from high strength steel that is compatible with the following vacuum hoses: 5/32" (4mm), 3/16" (5mm), and 7/32" (6mm).
2. 3AN Male Fitting: A black zinc-plated adapter machined from high strength steel that is compatible with 3AN hose ends.
3. Push-To-Connect: A nickel-plated brass fitting with Buna-N O-rings that is compatible with hard plastic 1/4" OD tubing.
4. Vacuum Plug: A black oxide stainless steel screw that is used to maintain a constant (non dynamic) fuel pressure.
Two kits are offered; one that feeds the fuel rails in series, and another that feed the fuel rails in a parallel configuration. Both kits perform equally well. The end decision is based on personal preference. Scroll down for details on each kit.
IMPORTANT NOTES
1. Neither kit includes a fuel filter.
2. Neither kit is compatible with Radium dual port injector fuel rail kit 20-0499.
3. Both kits are safe to use with alcohol fuels such as methanol, ethanol, E85 etc.
4. Both kits use 3/8" (6AN) high pressure EFI fuel hose.
20-0978 FUEL RAIL PLUMBING KIT, SUBARU EJ, SERIES
COMPATIBILITY
Subaru EJ2X Engines
For early vehicles with an engine bay mounted fuel filter, consult the installation instructions.
OVERVIEW
This fuel rail plumbing kit interfaces with the factory hard lines near the LH strut tower using SAE quick connects or older hose barb connections. A DMR-RA regulator (shown below) and a 0-100psi fuel pressure gauge are included.
The fuel pressure gauge can be installed at any of the 6AN junctions before the regulator using the included adapter. The 6AN swivel fuel rail fittings are low profile making them ideal for the tight spaces associated with the EJ motor. The variety of reuseable PushLok hose ends permit customizing (such as adding a flex fuel sensor) making installation quick and painless.
The included 6AN fuel hose can be cut with standard tools and assembled without special skills.
20-0984 FUEL RAIL PLUMBING KIT, SUBARU EJ, PARALLEL
COMPATIBILITY
08-14 Subaru Impreza STi
15-21 Subaru STi
OVERVIEW
Because the hoses and fittings are consolidated, the parallel kit is a good option for cleaning up the engine bay. Each fuel rail is fed as shown in the photo above. The feed and return lines enter the MPR-RA regulator from the rear and output through the front to the fuel rails.
The regulator secures to the LH strut tower using the provided stainless steel mounting bracket.
A 0-100psi fuel pressure gauge is included for calibration. Fittings and 6AN hose are included to interface with the OEM feed and return hard lines. If aftermarket -AN hoses/lines have replaced the factory piping, this kit can still be used (contact info@radiumauto.com for details).