Radium Engineering Direct Mount Fuel Pulse Damper Kits (20-0176)

Those lean AFR spikes your tuner can't tune out might not be a tuning problem at all.

Every injector opening and closing event sends a pressure pulse through the fuel rail, and with high-flow injectors those oscillations add up to unstable rail pressure, idle surge, and stumbles that show up as random lean spikes on the wideband. The Radium Engineering Direct Mount Fuel Pulse Damper Kit threads into an 8AN ORB or 3/8" NPT port on your rail and uses an internal diaphragm to absorb those pulses, with a vacuum/boost reference port that keeps the damper working correctly at elevated fuel pressures. Available as the FPD-R (40-70 psi base pressure) or FPD-XR (40-105 psi base pressure). Stable rail pressure across the whole RPM range, measured, not marketed.

What You'll Feel

• A smoother idle, especially on big injectors that used to surge
• Lean stumbles disappearing from spots in the RPM range no tune could fix
• A cleaner, more consistent AFR trace on the wideband from tip-in to redline
• Freedom to mount it at any angle, even upside down, wherever the rail allows
• One less variable to chase during dyno sessions

Features

• Internal diaphragm absorbs injector pressure pulses and stabilizes rail pressure
• Vacuum/boost reference port maintains damping at elevated pressures, essential with 1:1 rising-rate regulators
• FPD-R: 40-70 psi base static pressure range; FPD-XR: 40-105 psi base static pressure range
• 8AN ORB versions (20-0776 FPD-R, 20-0777 FPD-XR) seal with an FKM O-ring and swivel 360 degrees after tightening to clock the vacuum port
• 3/8" NPT versions (20-0178 FPD-R, 20-0179 FPD-XR) seal on tapered threads and clock during tightening
• Safe for all fuel types including alcohol blends such as E85

The Details

Base static pressure is what your gauge reads with the pump running and no vacuum line on the regulator, and it determines which damper you need. If your base pressure sits between 40 and 70 psi, the FPD-R covers you; between 70 and 105 psi, step up to the FPD-XR. Dynamic pressure from a rising-rate regulator can swing outside those ranges and the damper still works, as long as base pressure was set within range and the vacuum/boost reference line is connected. That reference port is what separates Radium's design from OEM-style dampers, which fall out of their working range as boost drives rail pressure up. For best results mount the damper directly on the fuel rail, though some systems also benefit from one on the return line. Two hard limits: these dampers cannot be used with mechanical fuel pumps or on the high-pressure side of direct injection systems, because those pressure pulses will rupture the diaphragm. For a 6AN ORB port, Radium's 14-0600 adapter (sold separately) adapts either 8AN ORB damper.

Kit Includes

• 1x Anodized, laser engraved aluminum top (R or XR)
• 1x Anodized aluminum body with male threads (8AN ORB or 3/8" NPT per selection)
• Stainless steel hardware
• Rubber vacuum hose, 4mm ID
• 1x Vacuum hose Y-fitting

Applications

• Universal: any fuel rail or fitting with an 8AN ORB or 3/8" NPT female port
• 6AN ORB ports supported with optional 14-0600 adapter (sold separately)
• Port fuel injection systems only; not compatible with mechanical fuel pumps or direct injection high-pressure circuits