Radium Engineering FHST – Nissan 370Z

The Radium Engineering FHST (Fuel Hanger Surge Tank) is the ultimate solution for fuel starvation issues in the Nissan 370Z (Z34) chassis. Due to the saddle-bag style OEM fuel tank and insufficient baffling, fuel starvation can occur when the vehicle is driven aggressively, such as on a track, resulting in unstable fuel pressure and potential engine damage from running lean. While a stand-alone surge tank can solve fuel starvation issues, installation in the 370Z is difficult due to the open-cabin design and lack of a firewall between the driver and the rear of the vehicle. Therefore, Radium Engineering designed a fully functional fuel surge tank that installs inside the OEM tank, providing superior performance without the need for extensive modifications.

The FHST can support 1 or 2 aftermarket pumps and provides 1:1 regulated fuel to the engine. No grinding, bending, or modification of the vehicle's sheet metal is required. Additionally, the system is compatible with alternative fuels such as E85.

Features:

• Drop-in installation with no modifications required

• Permits 1 or 2 surge pumps

• Integrated 1:1 adjustable fuel pressure regulator

• Fuel pressure gauge included

• Fuel starvation protection with integrated 1-way fill valves

• High current electrical hardware included

• Compatible with popular fuel pumps (brushed and brushless)

• Anodized aluminium construction for strength and durability

• Fuel resistant tubing and wiring

• Stainless steel hardware included

• Compatible with gasoline, methanol, ethanol, and E85

• New anti-rotation electrical terminals

How the FHST Works:
The OEM fuel module contains the pump, fuel pressure regulator, filter, and 2 venturi jet pumps that draw fuel from both sides of the tank. However, these systems can still suffer from fuel slosh, which interrupts fuel delivery during aggressive driving. The Radium FHST installs on the opposite side of the fuel tank from the OEM fuel module and works with it to keep fuel delivery consistent under all conditions.

The FHST uses the OEM fuel pump hanger (with an upgraded pump) to send fuel to the FHST, keeping the collector box filled. The OEM venturi jet pumps continue to function as designed, scavenging fuel from the bottom of the tank. The FHST pump(s) deliver fuel to the engine via the integrated fuel pressure regulator.

The FHST is supplied with fuel from 3 sources: the pump in the OEM fuel module, the fuel pressure regulator return, and the 355LPH one-way fill valves located on the bottom of the collector box. These valves allow fuel in but not out, ensuring the pump(s) feeding the engine are always supplied with fuel, even during extreme driving conditions.

Notes:

1. The OEM venturi system must be used with the Radium FHST.

2. The OEM fuel module must be upgraded to a pump with at least 340LPH (@ 40psi) rated flow for the venturi system to function correctly.

3. Do not modify the OEM FPR or OEM venturi jet pump.

4. Fuel starvation will not prematurely occur, but fuel may distribute unevenly in the tank, causing inaccurate fuel level readings.

5. This system can only be used as a traditional "return" style system if 20-0806 is purchased (see below).

Integrated Fuel Pressure Regulator:
Because the Nissan fuel system is "returnless", forced induction tuning can be problematic without a 1:1 fuel-to-boost pressure ratio. Like the OEM system, the FHST integrates a fuel pressure regulator. This regulator is externally mounted and features an adjustment screw and a vacuum port. If connected to the intake manifold vacuum hose, the regulator will operate at a 1:1 ratio, permitting fuel pressure to increase proportionally with manifold (boost) pressure. Alternatively, the vacuum port can be left open to atmosphere, maintaining constant fuel pressure like the OEM setup.

Plumbing:
To clear the OEM LH cover plate, the 8AN ORB threaded feed port and 6AN ORB threaded inlet port feature pre-installed low-profile 6AN male fittings. The 6AN ORB threaded FPR port is plugged and is only used if 20-0806 is purchased.

The FHST "IN" fitting cannot be changed, as it incorporates a unique component necessary for the venturi system to function correctly.

Two 6AN fuel hoses are provided to connect the two sides of the fuel tank units. The system also includes adapter fittings to reconnect the OEM fuel feed line. For high-flow applications, it is recommended to use a large 8AN fuel feed line from the FHST to the fuel rail(s). A custom 8AN fuel line will need to be configured and assembled by the installer.

Electrical:
The FHST features anti-rotation stainless steel electrical studs capable of handling the high current demand. These connections are hermetically sealed and impervious to all standard and exotic fuels. Non-conductive anodized aluminium acorn nuts prevent accidental short-circuiting. The wiring is insulated with high-quality chemically resistant ETFE.

The kit includes one relay, one fuse, and all necessary wiring and hardware for the installation of one surge tank pump. If installing an additional pump, the Radium 17-0031 DIY Wiring Kit (sold separately) will be required.

Pump Compatibility:
The FHST is compatible with both brushed and brushless fuel pumps, including:

• 20-1820-00 – Walbro GSS342 255lph, AEM 50-1200 E85

• 20-1821-00 – Ti Automotive BKS1001 (brushless)

• 20-1822-00 – Walbro F90000267 E85, Walbro F90000274 E85, Walbro F90000285 E85

The kit is partially assembled, and enough plumbing components are provided to run one or two surge tank fuel pumps. Fuel pumps must be purchased separately.