Radium Saddle Tank Fuel Cell Conversion Kit | Universal (20-0664)

Two fuel cells, one fuel system, and the weight put exactly where you want it.

The Radium Engineering saddle tank fuel cell conversion kit is a fuel transfer system that lets two motorsports fuel cells work together in one vehicle, optimising carrying capacity and weight distribution. The cells can be positioned strategically for balance and a low centre of gravity, and they do not have to be the same capacity, though their top flanges should sit at the same height. Fittings and hoses are included for mounting the units either transversely or longitudinally.

What You'll Feel

• More total fuel aboard without one enormous cell dictating the layout
• Weight placed for balance and a low centre of gravity
• Mixed cell capacities allowed, so the second cell fits the space available
• Transverse or longitudinal mounting, with hardware for both in the box

Features

• Fuel transfer system linking a passive cell to an FCST-X equipped active cell
• 1.5in OD stainless steel TEE for fill plumbing, orientable vertically or horizontally
• Fittings and hoses for both transverse and longitudinal installations
• Compatible with standard and dry break refuelling systems
• 1.5in ID tubing included, suiting any remote filler with a 1.5in OD barb

The Details

This is a system build, not a bolt-on, so read the required components carefully. You need two Radium fuel cells, a Radium FCST-X surge tank, a minimum of three fuel pumps (two lift pumps and one surge tank pump), and a remote filler or refuelling kit. Previous non-X FCST models are not compatible, because they lack the lift pump access the FCST-X handle provides. When sourcing lift pumps, make sure they have built-in check valves in the outlets; pumps without them can back-feed and cause operational failures.

On plumbing, the rollover valve in the FCST-X is removed and its vent port becomes the overflow, passing air and fuel back to the passive side, with the rollover vent fitting relocated to the passive cell's vent port. Because of that, the active cell must fill just before the passive cell. The TEE's orientation decides which cell fills first, and it moves the filler to the opposite side of the system, so the choice follows your vehicle's filler location.

Control logic deserves planning. Some custom logic is required for the passive cell's lift pump: it needs a level sender resistance signal to know when the passive cell is empty so it can shut that pump down. The active cell's lift pump can be controlled with the 20-0461 fuel level switch, which turns it on whenever the surge tank level drops. Two Radium fuel level senders are suggested; wiring two 0-90 ohm senders in series creates a 0-180 ohm range, or wired to independent ECU inputs the passive sender can handle that pump control directly.

Kit Includes

• Saddle tank conversion hardware for the secondary fuel cell
• 1.5in OD stainless steel TEE and 1.5in ID tubing
• Fittings and hoses for transverse or longitudinal mounting
• Vent fitting relocation hardware
• NOT included: fuel cells, FCST-X surge tank, fuel pumps, fuel level senders, fuel level switch (20-0461), and remote filler kit

Applications

• Universal, for pairing two Radium RA-Series fuel cells where the active cell carries an FCST-X surge tank

Important Notes

• Requires an FCST-X; previous non-X FCST models are NOT compatible
• Minimum three fuel pumps required: two lift pumps and one surge tank pump
• Lift pumps must have integrated check valves or they can back-feed
• Cell top flanges should be mounted at the same height
• Custom control logic is required for the passive cell lift pump
• Not CARB legal; not for sale or street use in California and CARB states