Radium Engineering Fuel Hanger Surge Tank – Mazda RX7 FD

This Radium Engineering system is a complete, drop-in fuel hanger surge tank solution for the Mazda RX-7 FD3S. It replaces the factory pump module with an integrated 1.85L fuel surge tank designed to completely eliminate fuel starvation during high-G cornering and acceleration. No cutting or modification to the OEM tank or trunk floor is required.

Vehicle Compatibility

• 1992–2002 Mazda RX-7 FD3S

Pump Compatibility

20-0952 (3x Pump Support)

• Walbro F90000267

• Walbro F90000274

• Walbro F90000285

• Walbro F90000295 *

20-0950 (2x Pump Support)

• Walbro GSS342 255LPH

• AEM 50-1200

• AEM 50-1230 *

• AEM 50-1235 *

20-0951 (1x Brushless Pump Support)

• Ti Automotive E5LM **

* These pumps do not feature a check valve. If required, use:

• 20-1533 (AEM GSL or 1230 series)

• 20-1534 (F90000295 or E5LM)

Integrated Surge Tank Design

The in-tank 1.85L surge canister is continuously filled via a dedicated lift pump mounted inside the OEM sub tank. This pump is supplied with fuel through a baffled mount and 1" check ball system that ensures fuel retention during deceleration and access during acceleration.

The lift pump feeds the surge tank through a 24-hole diffuser that minimizes bubbles and foaming. Overflow from the surge tank recycles back into the OEM sub tank.

Surge tank pumps (up to 3 supported depending on model) are protected by triple pre-pump stainless filters and discharge through a single 10AN billet outlet. A second diffuser handles low-pressure return fuel from the regulator, maintaining a constantly filled tank and reducing aeration.

Electrical & Plumbing

• High current stainless bulkhead studs

• Chemically resistant ETFE wiring

• Anti-rotation electrical terminals

• Submersible PTFE tubing

• Includes hardware for OEM fuel level sender and temperature sensor

• Pre-assembled with fittings and electrical for up to 4 pumps

• 10AN ORB feed outlet (with pre-installed 8AN male fitting)

• 8AN ORB return inlet (with pre-installed 6AN male fitting)

• OEM hose barb adapters included (8.5mm)

Notes

1. Fuel pumps are not included and must be sourced separately.

2. All models ship preassembled with enough components for up to 3 surge pumps and 1 lift pump.

3. Final assembly (pump installation) is performed by the installer.

4. Not compatible with other chassis or models—RX-7 FD3S only.