Radium Engineering In-Tank Fuel Hanger Surge Tank – Mazda RX-7 FD (FD3S) | Ti Automotive E5LM | Pumps Not Included

The Radium Engineering In-Tank Fuel Hanger Surge Tank for the Mazda RX-7 FD (FD3S) is a purpose-engineered in-tank fuel system solution designed to eliminate fuel pump starvation during the aggressive cornering, hard braking, and sustained high-G driving conditions that the FD3S is subjected to in performance and competition use — conditions where the factory fuel system's pickup and pump arrangement can allow fuel to surge away from the pump inlet, causing momentary fuel pressure loss that can be catastrophic for the 13B-REW's rotary engine. The Radium hanger integrates a Ti Automotive E5LM surge tank directly into the FD3S's factory fuel tank — maintaining a constant reservoir of fuel around the pump inlet regardless of fuel level or lateral G-forces — and supports multiple pump configurations for high-power 13B builds that exceed the flow capacity of a single pump. Fuel pumps are not included and must be sourced separately.

Key Features:

• In-tank surge tank design — Ti Automotive E5LM surge tank integrated into the Radium fuel hanger — maintains a constant fuel reservoir around the pump inlet regardless of fuel level or lateral G-forces — eliminates fuel starvation at the pump
• Multi-pump capable — designed to accommodate multiple fuel pumps — supports the high fuel flow requirements of high-power 13B builds that exceed the capacity of a single pump
• Eliminates fuel starvation — the surge tank's constant fuel reservoir prevents the pump inlet from being uncovered during aggressive cornering, hard braking, and sustained high-G driving — the primary cause of fuel pressure loss in performance FD3S applications
• Factory and aftermarket fuel line compatible — can be used with the factory FD3S fuel lines or aftermarket fuel line setups — correct for a range of FD3S fuel system configurations
• FD3S specific — engineered for the Mazda RX-7 FD (FD3S) fuel tank — correct dimensions and fitment for the FD3S in-tank installation
• Radium Engineering quality — manufactured by Radium Engineering, one of the most respected fuel system engineering brands in the performance aftermarket
• Pumps not included — fuel pumps must be sourced separately — verify compatible pump specifications with Radium Engineering's documentation before ordering

Why the FD3S Needs an In-Tank Surge Tank:

• Factory Fuel System Limitation: The FD3S RX-7's factory fuel system is engineered for the 13B-REW's stock fuel requirements — adequate for stock power levels but increasingly marginal as power increases. More critically, the factory fuel pickup arrangement is susceptible to fuel starvation under the high lateral G-forces of aggressive cornering and track use — fuel surges to one side of the tank, uncovering the pickup and causing momentary fuel pressure loss. For the 13B-REW rotary engine, even brief fuel pressure loss under boost can cause lean conditions that result in apex seal damage, rotor damage, or catastrophic engine failure.
• Surge Tank Solution: An in-tank surge tank maintains a constant reservoir of fuel immediately around the pump inlet — the surge tank fills from the main tank and acts as a buffer that keeps the pump inlet submerged in fuel regardless of the main tank's fuel level or the lateral G-forces acting on the fuel. The pump draws from the surge tank rather than directly from the main tank — eliminating the starvation risk that the factory pickup arrangement creates under high-G conditions.
• High-Power 13B Builds: High-power 13B builds — single or twin turbo conversions, ported engines, E85 conversions — require significantly more fuel flow than the factory 13B-REW. The Radium hanger's multi-pump capability allows two or more pumps to be installed in the surge tank — providing the combined flow capacity required for high-power applications while maintaining the starvation protection of the surge tank design.
• Rotary Engine Sensitivity: The 13B-REW's rotary engine is particularly sensitive to fuel system issues — the rotor's apex seals and the rotor housing are vulnerable to heat damage from lean conditions caused by fuel starvation. A fuel system that cannot maintain consistent fuel pressure under all driving conditions is a serious reliability risk on a high-power FD3S build. The Radium surge tank eliminates this risk.

Ti Automotive E5LM Surge Tank:

The Ti Automotive (formerly Walbro) E5LM is a compact, high-quality surge tank designed for in-tank installation — used by Radium Engineering as the surge tank component in their FD3S hanger assembly. Ti Automotive is one of the most respected fuel system component manufacturers in the performance aftermarket — known for their high-flow fuel pumps and fuel system components used in OEM and aftermarket applications globally. The E5LM's compact dimensions allow it to be integrated into the FD3S's fuel tank without modification while providing the surge tank volume required for effective fuel starvation protection.

Specifications:

• Brand: Radium Engineering
• Part Number: RAD20-0951
• Barcode: Radium 20-0951
• Surge Tank: Ti Automotive E5LM
• Configuration: Multi-pump capable
• Application: Mazda RX-7 FD — FD3S chassis
• Weight: 5.5 lbs
• Pumps: Not included — must be sourced separately

Fitment Information:

• Mazda RX-7 FD — FD3S chassis (1992–2002)
• In-tank installation — installs inside the FD3S factory fuel tank using the factory fuel hanger opening
• Compatible with factory and aftermarket FD3S fuel lines — verify fuel line compatibility for your specific FD3S fuel system configuration
• Note: Fuel pumps are not included — must be sourced separately. Verify compatible pump specifications, dimensions, and flow rates with Radium Engineering's product documentation before selecting pumps. Professional installation by an experienced fuel system specialist strongly recommended — in-tank fuel system work requires correct fuel system depressurization, correct assembly procedures, and leak testing before returning the vehicle to use.

What's Included:

• Radium Engineering fuel hanger assembly with Ti Automotive E5LM surge tank — Mazda RX-7 FD FD3S (RAD20-0951)
• All required hardware for hanger installation
• Refer to Radium Engineering's product documentation for complete kit contents
• Fuel pumps not included — must be sourced separately

Installation Notes:

• Professional installation by an experienced fuel system specialist strongly recommended — in-tank fuel system work requires correct fuel system depressurization, correct assembly, and thorough leak testing
• Depressurize the fuel system before beginning installation — the FD3S fuel system retains pressure after engine shutdown. Follow the correct depressurization procedure before opening any fuel system connections.
• Work in a well-ventilated area away from ignition sources — fuel vapour is highly flammable. Do not smoke or use open flames near the fuel tank during installation.
• Source and install compatible fuel pumps before installing the hanger assembly — verify pump dimensions, flow rate, and electrical specifications with Radium Engineering's documentation for the E5LM surge tank
• Verify all fuel system connections for leaks after installation and after the first fuel system pressurization — any fuel leak in the tank or at the hanger connections is a serious fire risk
• Prime the fuel system before starting the engine after installation — cycle the ignition key to the ON position several times without cranking to allow the pump(s) to pressurize the fuel system
• A professional tune is recommended after fuel system upgrades on high-power 13B builds — verify fuelling and fuel pressure under load before sustained high-power use

Why Radium Engineering?

Radium Engineering is one of the most respected fuel system engineering brands in the performance aftermarket — known for their in-tank fuel hangers, surge tanks, fuel rails, and fuel system accessories for a wide range of performance platforms. Radium's engineering-first approach produces fuel system solutions that are trusted by professional race teams and serious performance builders who demand reliable, correctly-engineered fuel delivery under the most demanding conditions. For FD3S RX-7 owners who want a quality in-tank surge tank solution from a brand that understands the demands of high-performance fuel system engineering, Radium Engineering is the correct choice.

Perfect For:

• Mazda RX-7 FD (FD3S) owners building high-power 13B applications — single or twin turbo conversions, ported engines, E85 conversions — where the factory fuel system's flow capacity and starvation protection are insufficient
• FD3S track day and competition builds where high lateral G-forces create fuel starvation risk with the factory fuel pickup arrangement
• High-power FD3S builds requiring multiple fuel pumps for combined flow capacity beyond what a single pump can provide
• Owners completing a comprehensive FD3S fuel system upgrade — pairing the Radium hanger with high-flow Ti Automotive pumps, a fuel pressure regulator, and upgraded fuel lines for a complete high-flow fuel system

Critical Notes: Fuel pumps not included — must be sourced separately — verify compatible pump specifications with Radium Engineering before ordering. Depressurize fuel system before installation. Work away from ignition sources. Verify all connections for fuel leaks after installation — any fuel leak is a serious fire risk. Professional installation strongly recommended. Prime fuel system before first start after installation.