Radium Engineering 20-1102 DFPR Dual Fuel Pressure Regulator

The Radium Engineering Dual Fuel Pressure Regulator (DFPR) was specifically designed for custom fuel systems that use both direct injection and port injection. The DFPR allows for independent fuel pressures for each system with a single feed input. Additionally, its design suppresses pressure spikes generated by the mechanical (positive displacement plunger) High Pressure Fuel Pump (HPFP) used for direct injection. FPR1 is used for direct injection and FPR2 is used for port injection.

INSTALLATION

The DFPR is designed to be installed upstream (before) the High Pressure Fuel Pump (HPFP) and the port injection fuel rail.

PUMP INLET: Thread: 3/4-16" (8AN ORB). This is the only inlet. The Low Pressure Fuel Pump (LPFP) output should be connected to a low-micron fuel filter and then to this inlet.

FPR1 OUTLET: Thread: 3/4-16" (8AN ORB). This outlet should be connected directly to the High Pressure Fuel Pump (HPFP) inlet. FPR2 Outlet: Thread: 3/4-16" (8AN ORB). This port should be connected directly to the multi-port injection fuel rail. Cap off the opposite end of the fuel rail. NOTE: If the engine does not have multi-port injection, this port can be capped off without affecting FPR1. For FPR1 to function correctly, turn the FPR2 knob completely counterclockwise.

Return: Thread: 3/4-16" (8AN ORB). This port should be connected directly to the fuel tank (or surge tank). NOTE: If the fuel tank does not have a return port, these barbed hose adapters may be an option for returning fuel to the filler neck. AUXILIARY SENSOR PORT (FPR1) Thread: 1/8"-27 NPT. For monitoring FPR1, this port can be used for gauges, sensors, etc. A plug is included.

AUXILIARY SENSOR PORT (FPR2) Thread: 1/8"-27 NPT. For monitoring FPR2, this port can be used for gauges, sensors, etc. A plug is included.

FUEL PRESSURE ADJUSTMENT

RA series regulators incorporate the first tool-free pressure adjustment. No longer are a locknut and adjustment screw required. With a simple turn of the knob, pressure is increased or decreased. In addition, there is no air (vacuum/boost) leakage through the threads that a smoke detector would traditionally detect. To facilitate pressure adjustment, incremental detents provide haptic feedback to the user. Each detent allows for a 1 psi (+/-0.5 psi) adjustment based on current fuel pressure.
NOTE: FPR2 pressure will always be equal to or less than FPR1. It physically cannot be greater.

FUEL PRESSURE STABILITY: Through years of track and dyno testing data, RA series regulators have been refined for optimal pressure management. A unique new stainless steel return orifice generates laminar flow, which improves stability control.

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

*This is rhetorical. Maximum pressure depends on the relief valve inside the pump or the maximum current allowed by the fuel pump controller.

1:1 RISE RATE VACUUM REFERENCE

NOTE: If FPR2 has a 1:1 boost reference, FPR1 pressure will increase accordingly to match FPR2.

RA series regulators feature a 360-degree rotating vacuum reference port with a dual O-ring seal. This is an industry first. It allows the installer to quickly orient the vacuum connection in any direction without the need for tools. 4 interchangeable 10-32 threaded vacuum fittings are included to cover all needs.

Barbed Fitting: A 3/16" (5mm) black zinc-plated barbed fitting, machined from high-strength steel, 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, compatible with 3AN hose ends. Quick-Connect: A nickel-plated brass fitting with Buna-N O-rings, compatible with 6mm (1/4") OD rigid plastic tubing.

Vacuum Plug: A black oxide stainless steel screw used to maintain constant (non-dynamic) fuel pressure. In the mid-1990s, vehicle manufacturers began transitioning to returnless fuel systems to reduce evaporative (EVAP) emissions. To keep temperatures low, these regulators are mounted inside the tank and CANNOT have a vacuum reference. This plug would be required in this case. NOTE: When installing the vacuum fitting, medium-strength threadlocker with good wicking ability is recommended.

FUEL COMPATIBILITY

All RA series regulators are compatible with all types of gasoline, including unleaded, leaded, oxygenated, and premixed gasoline. Additionally, they are compatible with alcohol fuel blends such as methanol, ethanol, and E85.

INCLUDES

Fuel Pressure Regulator (DFPR) Main Swivel Assembly
Mounting bracket with hardware
5mm barbed vacuum fittings (x2)

1/4" quick-connect vacuum fittings (x2)

3AN male vacuum fittings (x2)

Plug-type vacuum fittings (x2)

8AN ORB to 6AN male fittings (x4)

8AN ORB to 8AN male fittings (x4)

8AN ORB plug

Instructions (PDF)