Radium V2 FPD-XR Extended Range Fuel Pulse Damper, 8AN ORB

The Radium Engineering 20-0777 V2 FPD-XR is an extended range fuel pulse damper for high-performance and boosted fuel systems. Designed to absorb oscillating pressure pulses created by fuel injector opening and closing, the FPD-XR stabilises fuel rail pressure across the entire RPM range — correcting idle surge, erratic lean AFR spikes, and "stumbling" that are difficult to tune out, especially with high-flow injectors.

V2 Update: Even after tightening, the 8AN ORB damper (20-0777) swivels freely, allowing the vacuum reference port to be clocked 360° for easy routing in any installation.

What Makes Radium FPDs Unique?

Unlike basic fuel pulse dampers, Radium FPDs feature a vacuum/boost reference port that allows the damper to maintain correct performance even at elevated fuel pressures. This is essential for boosted applications running a 1:1 rising rate fuel pressure regulator, where fuel pressure rises with boost and a non-referenced damper would become ineffective.

FPD-R vs FPD-XR — Which Do I Choose?

Both dampers share the same function but have different base static fuel pressure operating ranges:

• FPD-R (green top, 20-0776) — base static pressure: 40-70psi. Slightly shorter for space-constrained applications.
• FPD-XR (black top, 20-0777) — base static pressure: 40-105psi. Extended range for higher base pressure applications.

Base pressure = fuel pressure measured with the pump running and no vacuum line connected to the regulator.

Important: The ranges above are base static pressures only. Dynamic pressure created by a rising-rate FPR outside this range is acceptable, provided the base static pressure is set within the specified range and the vacuum/boost reference line is connected.

Worked Examples

Example 1 — Mitsubishi EVO: OEM base static pressure 43.5psi, 30psi boost, rising rate FPR.

• FPD-R: ✔ Yes — base pressure within 40-70psi range. Vacuum/boost reference line must be connected.
• FPD-XR: ✔ Yes — max fuel pressure (73.5psi) does not exceed 105psi. Reference line not required but recommended.

Example 2 — BMW E46 M3: OEM base static pressure 72.5psi, 20psi boost, rising rate FPR.

• FPD-R: ✘ No — base static pressure exceeds the 40-70psi range.
• FPD-XR: ✔ Yes — max fuel pressure (92.5psi) does not exceed 105psi. Reference line not required but recommended.

Key Features

• Extended range: 40-105psi base static pressure — suits a wide range of high-pressure fuel systems
• Vacuum/boost reference port — maintains correct damper performance under boost with a rising rate FPR
• 360° swivel vacuum port — V2 design allows clocking after installation for easy routing
• 8AN ORB connection — Viton O-ring sealed, compatible with standard AN fuel rail fittings
• 3/8" NPT version also available — tapered pipe thread seal (see 20-0776 for FPD-R)
• Mounts at any angle including upside down — flexible installation for any fuel rail layout
• E85 and alcohol fuel safe — compatible with all fuel types
• Anodised and laser engraved aluminium housing — premium finish, permanent identification

Kit Includes

• Anodised and laser engraved aluminium top (XR = extra range, black)
• Anodised aluminium body with 8AN ORB male threads
• Stainless steel hardware
• Rubber vacuum hose, 4mm ID
• Vacuum hose Y-fitting

Available Part Numbers

• 20-0777 — V2 FPD-XR, 8AN ORB (this damper — 40-105psi base static range)
• 20-0776 — V2 FPD-R, 8AN ORB (40-70psi base static range, shorter body)

Why Radium Engineering?

• ✔ Designed and manufactured in the USA
• ✔ Vacuum/boost reference port — industry-leading performance under boost
• ✔ V2 360° swivel vacuum port — easy installation in any orientation
• ✔ Trusted by professional motorsport teams and serious enthusiasts worldwide
• ✔ Exclusively distributed in Australia by Coore

Genuine Radium Engineering product. Stocked in Sydney for fast Australian delivery. Best mounted directly on the fuel rail. Download installation instructions for full setup guidance.