The opening and closing of fuel injectors creates pressure pulses in the fuel rail which can lead to unstable fuel pressure. In order to achieve a safe and consistent rail pressure, a fuel pulse damper (FPD) is often necessary. The FPD's internal diaphragm will absorb oscillating pulses and stabilize fuel pressure. This correction can be measured throughout the RPM range and can often help idle surge, especially with high flow injectors. Furthermore, a fuel pulse damper can help solve erratic lean air/fuel ratio spikes, commonly experienced as "stumbling", that are difficult to tune out.
What makes Radium FPDs unique?
Along with having the flexibilty of using common fittings, Radium Engineering FPD's use a vacuum/boost reference port which allows for proper fuel pulse damper performance even at elevated fuel pressures. This becomes essential for boosted systems that use a 1:1 rising rate fuel pressure regulator.
What is the difference between FPD-R and FPD-XR?
The FPD-R (green top) is slightly shorter than the FPD-XR (black top) allowing it to be used in space-contrained applications.
Furthermore, the FPD-R (Fuel Pulse Damper-Range) and FPD-XR (Fuel Pulse Damper-Extra Range) both have unique base "static" fuel pressure requirements.
FPD-R base pressure requirement = 40 - 45psi (static)
FPD-XR base pressure requirement = 43 - 78psi (static)
IMPORTANT: The ranges above are base static fuel pressures only. Any dynamic fuel pressure created by a rising-rate FPR outside of this range is acceptable, but only when the base "static" fuel pressure is set within these ranges and the vacuum/boost reference line is hooked up.
Example 1:
Vehicle: Mitsubishi EVO
OEM Base Static Fuel Pressure: 43.5psi
Boost Pressure: 20psi
Rising Rate Pressure Regulator?: Yes
Notes: Even though fuel pressure is 63.5psi at full boost, either FPD-R or FPD-XR can work in this example because the base static pressure was set within the requirements. Vacuum/boost reference line must be hooked up to the FPD.
Example 2:
Vehicle: 06+ Honda S2000
OEM Base Static Fuel Pressure: 60psi
Rising Rate Pressure Regulator?: No
Notes: The FPD-XR will work in this example because the base static pressure was set within the requirements. The FPD-R cannot be used in this scenario. No vacuum/boost reference hooked to FPD, port left open.
Example 3:
Vehicle: BMW E46 M3
OEM Base Static Fuel Pressure: 72.5psi
Boost Pressure: 20psiv
Rising Rate Pressure Regulator?: Yes
Notes: Even though fuel pressure is 92.5psi at full boost, the FPD-XR will work in this example because the base static pressure was set within the requirements. The FPD-R cannot be used in this scenario. Vacuum/boost reference line must be hooked up to the FPD.
Features
The kit features an anodized aluminum housing with a large 0.69" center bore that uses two in-line inlet/outlet ports that are machined with 3/4"-16 UNF threads for 8AN ORB fittings. Depending on the size of the fuel feed hose used, there are 3 kits to choose from which include different male adapter fittings (-6AN, -8AN, -10AN). These fittings seal to the billet housing using Viton O-rings.
Using the supplied M6 bolts/nuts, the FPD kit can be mounted at any possible angle including upside down. For best results, the damper should be plumbed as close to the fuel rail(s) as possible. Like any fuel system part, the FPD kit should be kept away from excessive heat areas.
This product is safe for use with all fuel types including alcohol blends such as E85. Download the installation instructions for more info.
Included
-Anodized/laser engraved aluminium top, R=range or XR=extra range
-Anodized aluminium body threaded for -8AN ORB fittings
-Anodized aluminium O-ring sealed adapter fittings, selectable size
-Stainless steel M6 mounting bolts and nuts
-Rubber vacuum hose, 4mm ID
-Vacuum hose Y-fitting