OVERVIEW The opening and closing of fuel injectors creates pressure pulses in the fuel rail; this 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.Fuel pulse dampers can be mounted at any angle, including upside down. There are many variables that dictate if a fuel system requires fuel pulse dampers. For instance, there are cases where multiple dampers are necessary. There are also other times when the fuel system benefits with a fuel pulse damper on the return line. This product is safe for use with all fuel types including alcohol blends such as E85. UNIQUE DESIGN Along with having the flexibility 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 and in vacuum referenced regulators when fuel pressure falls under 40psi. HOW TO CHOOSE BETWEEN FPD-R VS FPD-XR The FPD-R (Standard Range) and FPD-XR (Extra Range) both have unique base/static fuel pressure requirements: FPD-R base pressure requirement = 40 - 70psi (static) FPD-XR base pressure requirement = 40 - 105psi (static) Base pressure is the fuel pressure measured when the fuel pump is running WITHOUT a vacuum line connected to the regulator. You should choose the damper that has a range that covers your base fuel pressure. If your base fuel pressure does not exceed 70psi, there is usually no advantage to using the extra range unit. The exception to this would be if your rising rate pressure exceeds 70psi, but never exceeds 105psi, and your falling rate under vacuum never moves under 40psi. In this scenario, the extra range damper would allow you to run without a vacuum line where the standard would require one. 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.
