Radium Direct Mount Regulator

The Radium Direct Mount Regulator (DMR) is a compact high performance adjustable EFI fuel pressure regulator that is capable of managing high flow fuel systems. It's compact package fits in tight spaces, but does not compromise on performance.

PLUMBING

The main inlet port on the regulator is female threaded for 6AN ORB. A swiveling double ended adapter (shown below) is included which allows the regulator to be used in any compatible 8AN ORB fuel rail port, such as those found Radium Engineering fuel rails. Other swivel adapters are available but sold separately. 

If mounting the regulator off-rail, other adapters can be screwed into this regulator port (sold separately HERE).

The bottom return port is threaded for 6AN ORB. The provided 90 degree 6AN male fuel return fitting can swivel 360 degrees, permitting a multitude of mounting configurations. Other adapter fittings can be installed in the return port if needed (sold separately).

This regulator has two 1/8' NPT side port locations that can be used with a pressure gauge, transducer, temperature probe, etc. Two 1/8' NPT plugs are provided.

FUEL PRESSURE ADJUSTMENT

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. Additionally, there are no inherent air (vacuum/boost) leaks through the threads that traditionally a smoke detector would pick up.

1:1 RISING RATE VACUUM REFERENCE

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.

• 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)
• 3AN Male Fitting: A black zinc-plated adapter machined from high strength steel that is compatible with 3AN hose ends
• Push-To-Connect: A nickel-plated brass fitting with Buna-N O-rings that is compatible with hard plastic 1/4' OD tubing

• Vacuum Plug: A black oxide stainless steel screw that is used to maintain a constant (non dynamic) fuel pressure. Beginning in the mid 1990s, vehicle manufacturers started transitioning to returnless fuel systems to lower EVAP emissions. To keep temperatures lower, these regulators are mounted inside the tank and do NOT have the ability to be vacuum referenced. This plug would be required in this scenario.

  NOTE: When installing the vacuum fitting, it is recommended to use a wicking medium-strength thread locker.

FUEL PRESSURE STABILITY

With years of track and bench testing data, the RA-series regulators have been refined to optimize pressure management. A newly designed single stainless steel return orifice generates laminar flow that enhances stability control.

Minimum Pressure: 18.5psi (1.3bar)
Maximum Pressure: *N/A

*This is rhetorical. The maximum pressure is dependent on the relief valve inside the pump or the maximum current the fuel pump controller allows.

ABOUT FUEL PRESSURE DROP AFTER SHUTOFF

Some installations may experience a rapid fall of fuel pressure when the engine and/or fuel pump shuts off. This is considered normal operation for aftermarket fuel pressure regulators, regardless of brand. 

This can occur due to the diaphragm seat and the return orifice not fully sealing when fuel flow is stopped. For regulators to have the ability to regulate high fuel flow rates, the size of these components must be increased. This creates larger sealing surfaces between the components, preventing them from forming a perfect seal, even with high spring rates. This is not an indication of an issue or defect and it is not a cause for concern on its own.

You do NOT need to contact technical support about this issue.

Fuel pressure will reset immediately when the fuel pump is activated again.

If the engine is experiencing other symptoms such as long cranking to start, or delays in pressure building when cranking, these symptoms are unrelated to the regulator. There is likely an issue with the fuel feed hose draining back to the tank. This is most likely due to an internal leak somewhere in the pump module: possibly a venturi jet pump, or the lack of a fuel pump check valve.

The DMR is designed with a unique highly versatile mounting system. It can be mounted directly to a 8AN ORB fuel rail using the included 360 degree swiveling adapter. If your fuel rail does not have an 8AN ORB port, Radium Engineering offers fuel rails for a wide variety of engines, all of which feature 8AN ORB ports (An adapter is also available for 10AN ORB fuel rail ports).

The compact size fits in areas with limited space, without sacrificing performance. Alternatively, the DMR can be mounted off-rail using remote mount kit 20-0624.