Radium Direct Mount Fuel Pulse Damper - FPD-R / FPD-XR (8AN ORB or 3/8" NPT)

Injector opening and closing creates pressure pulses in the fuel rail that can cause unstable fuel pressure, idle surge, and erratic lean AFR spikes (“stumbling”) that are difficult to tune out. The Radium Engineering Direct Mount Fuel Pulse Damper absorbs these oscillating pulses via an internal diaphragm, stabilising fuel pressure throughout the RPM range. Mounts directly onto the fuel rail for best results. Particularly effective with high-flow injectors and boosted applications using a 1:1 rising-rate FPR.

Radium FPDs feature a vacuum/boost reference port — essential for boosted systems running a rising-rate FPR, ensuring correct damper performance at elevated fuel pressures. Compatible with all fuel types including E85 and methanol.

FPD-R vs FPD-XR — Which to Choose?

FPD-R (Range) — Green top

• Base static fuel pressure requirement: 40-70 PSI
• Compact size — ideal for space-constrained applications
• Vacuum/boost reference line required for boosted applications exceeding 70 PSI dynamic pressure

FPD-XR (Extra Range) — Black top

• Base static fuel pressure requirement: 40-105 PSI
• Wider response range — Radium recommends the FPD-XR if space permits
• Vacuum/boost reference line not required if maximum fuel pressure does not exceed 105 PSI

Note: Base pressure = fuel pressure measured with the pump running and NO vacuum line connected to the regulator. Dynamic pressure from a rising-rate FPR outside these ranges is acceptable provided the base static pressure is set within the specified range and the vacuum/boost reference line is connected.

Selection Examples

Mitsubishi Evo — 43.5 PSI base, 30 PSI boost, rising-rate FPR: Both FPD-R and FPD-XR suitable. FPD-R requires vacuum/boost reference line connected.

BMW E46 M3 — 72.5 PSI base, 20 PSI boost, rising-rate FPR: FPD-R not suitable (base exceeds 70 PSI). FPD-XR required.

Thread Options

• 8AN ORB: Seals using a Viton O-ring — positive, leak-free seal
• 3/8" NPT: Seals with tapered pipe threads

The FPD can be mounted at any angle including inverted. For best results, mount directly onto the fuel rail.

Kit Includes

• Anodised and laser engraved aluminium top (R = green, XR = black)
• Anodised aluminium body with male threads (8AN ORB or 3/8" NPT per selection)
• Stainless steel hardware
• 4mm ID rubber vacuum hose
• Vacuum hose Y-fitting

Part Number:

• 20-0179 — Radium Direct Mount Fuel Pulse Damper (FPD-R / FPD-XR, 8AN ORB or 3/8" NPT)

Why Radium Engineering?

• ✅ Manufactured in the USA to motorsport-grade tolerances
• ✅ CNC-machined billet aluminium components built for performance and longevity
• ✅ Trusted by high-power build tuners and race teams worldwide
• ✅ Vacuum/boost referenced — correct performance at elevated fuel pressures on boosted builds
• ✅ Compatible with E85, pump petrol, methanol, and all exotic fuel types