What makes Radium FPDs unique?
Along with having the flexibility of using common AN fittings or directly mounted to your Radium fuel rail, 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 and which damper is right for my build?
- The FPD-R (green top) is slightly shorter and designed for 40-70psi base fuel pressure.
- The FPD-XR (black top) is slightly taller and designed for 40-105psi based fuel pressure.
Base pressure: The fuel pressure measured when the fuel pump is running WITHOUT a vacuum line connected to the regulator.
Included with your FPD kit:
-Anodized and laser engraved aluminum top, R=range or XR=extra range
-Anodized aluminum body with male threads, 8AN ORB or 3/8″ NPT
-Stainless steel hardware
-Rubber vacuum hose, 4mm ID
-Vacuum hose Y-fitting
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 connected.
Example 1: Vehicle: Mitsubishi EVO
- OEM Base Static Fuel Pressure: 43.5psi Boost Pressure:
- 30psi Rising Rate Pressure Regulator.
- Can I use a FPD-R? Yes. Even though fuel pressure is 73.5psi at full boost, the FPD-R will work because the base static pressure was set within the 40-70psi requirement. However, the vacuum/boost reference line must be installed.
- Can I use a FPD-XR? Yes.The vacuum/boost reference line does not need to be installed since maximum fuel pressure does not exceed 105psi.
Example 2: Vehicle: BMW E46 M3
- OEM Base Static Fuel Pressure: 72.5psi Boost Pressure: 20psi Rising Rate Pressure Regulator.
- Can NOT use the FPD-R. Base static fuel pressure exceeds the 40-70psi requirement.
- Can use a FPD-XR. The vacuum/boost reference line does not need to be installed since maximum fuel pressure does not exceed 105psi.
The 8AN ORB version (right) seals using a Viton O-ring while the 3/8″ NPT variation (left) seals with the tapered pipe threads. The FPDs can be mounted at any possible angle including upside down. For best results, the damper should be mounted directly onto the fuel rail(s). This product is safe for use with all fuel types including alcohol blends such as E85. Download the installation instructions for more info.