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For 20-049X-XX FCST installation instructions, click here
For 20-0693-00 FCST installation instructions, click here
For installation on older 20-014X-XX FCST versions, click HERE.

The Fuel Cell Surge Tank (FCST) is a drop-in fill plate replacement for popular fuel cells including Radium, ATL, FuelSafe, Pyrotect, Harmon, Jaz, etc. For a complete combo package with a Radium Engineering fuel cell go HERE.

The FCST is designed for EFI vehicles experiencing fuel pump starvation issues while using a competition fuel cell. It is NOT a glorified trap door box. It features a true dual-chamber fuel tank utilizing a single lift pump and up to three surge tank pumps, all in a compact drop-in package. This product also provides a quick and easy way to drop-in an upgraded fuel pump system for extra flow for vehicles with large power demand upgrades. Alcohol fuels such as E85, methanol, etc can be safely used. 

Is the FCST compatible with my XXX brand fuel cell?
To install a Radium FCST into a fuel cell, the following criteria must be met:
1. The cell must have the industry standard 6"x10" 24-bolt flange opening.
2. The opening must be on the top face of the fuel cell (i.e. not a side face).
3. The cell depth must be at least 7.6" (193mm) measured from the outer top face to the internal bottom face.


Integrated Surge Tank

The FCST uses the tried and true Radium Engineering fuel surge tank system preferred by professional motorsports teams worldwide. The optimized 2.2 liter canister supports 1, 2, or 3 internally mounted surge tank pumps capable of over 4000HP (Gas @ 3bar, BSFC .45).

The fuel pumps inside the surge tank provide the primary fueling to the engine. The "lift pump" mounts next to the surge tank canister and keeps the chamber filled. The volume of fuel inside the surge tank acts as a buffer always keeping the surge tank pump(s) supplied with fuel. This volume is also maintained by the "return" from the FPR. Excess fuel in the integrated surge tank bleeds out into the fuel cell without the need of expensive hoses and fittings. All of this is done inside the fuel cell with the FCST.

Because all of the compatible pumps utilize a check valve, the FCST merges all pumps into a single outlet simplifying external plumbing. The return port has a tangential entry into the FST canister creating a swirl pot. This helps eliminate unwanted air bubbles and fuel foam that can affect fuel pump and engine performance.

The FCST uses high current stainless steel wiring terminals. All internal wires are gasoline, ethanol, and methanol compliant. Furthermore, the internal tube and hoses are a special fluoroelastomer formulation that is suitable for submersion in all types of fuel.

All variations of the FCST found in drop-down menu come standard with the following parts:

-Radium 20-0146 Fuel Level Sensor Block-Off Kit 
-Radium 20-0435 Vent Valve, 12AN ORB to 8AN Male, Std Fill
-Anodized Aluminum 6x10, 24-Bolt Fill Plate
-Anodized Aluminum 2.2 Liter Surge Tank Canister
-Anodized Aluminum Lift Pump Mounting Brackets
-Anodized Aluminum Surge Tank Pump Cradle   
-Anodized Aluminum 6AN Male Return Fitting
-Anodized Aluminum 8AN Male Feed Fitting 
-Stainless Steel Hardware and Viton O-rings
-Insulated 10-32 Nuts for Electrical Studs
-Electrical Crimp-on Ring Terminals

-Click these links for compatible fillers (not included), Direct Mount or Remote Mount

20-049X-XX FCST
The 20-049X-XX Fuel Cell Surge Tanks are available with or without fuel pumps. Radium assumes the lift and surge tank pumps will be the same brand so the internal wiring connectors for all pumps will be the same. 

When the pumps "included" is ordered, the FCST will come pre-assembled and ready to be dropped into a fuel cell.

If the "pumps not included" option is ordered and fuel pumps will be sourced separately, a filter sock will only be required for the lift pump as a filter screen is supplied for the surge tank pumps. Also, there will be enough components included with this option to use multiple surge tank pumps. Depending on the setup, some parts may not be used. If you would like to use a different pump than what is listed, please contact Radium technical support. NOTE: Bosch 044 pumps are NOT compatible with this product.

The 20-049X-XX FCSTs include perimeter mounting tabs for older style fuel cells. NOTE: Radium fuel cells do not require these mounting tabs.

20-0693-00 FCST
The 20-0693-00 Fuel Cell Surge Tank is only available without pumps included.

However, Ti Automotive E5LM brushless fuel pumps can be purchased HERE. As shown below, the lift pump electrical and plumbing is set to be compatible with Walbro F90000267/274/285/295 fuel pumps. For dual brushless pump configurations, Radium recommends the Walbro F90000295 as a lift pump for maximum flow.

When ordering fuel pumps, make sure that each pump has a filter sock. However, there will be enough components included to use multiple surge tank pumps. Depending on the setup, some parts may not be used. 

Ti Automotive brushless fuel pumps do not use an integrated check valve. The 20-0693-00 FCST includes two 20-0598 fuel pump outlet adapter check valves (shown below). Because the 2 surge tank pumps merge into a single outlet collector, these high flow 1-way valves permit multiple pumps to be staged.

The 20-0693-00 FCST also comes standard with a 2AN ORB plug in the "level switch" port. For more information on adding a fuel level switch and diagnostic indicator, click HERE.

Fittings Explained

PUMP OUT-8AN MALE: The external fuel pump outlet port is signified by the "PUMP OUT" engraving. It is thread tapped with 7/8"-14 threads making it compatible with all 10AN ORB fittings. The FCST comes standard with a common 10AN ORB to 8AN male adapter fitting. However, various 10AN ORB adapter fittings can be purchased separately HERE.

RETURN-6AN MALE: The external "RETURN" port is used for low pressure fuel returning from the FPR. This port is tapped with 3/4"-16 threads making it compatible with all 8AN ORB fittings. The FCST comes standard with a common 8AN ORB to 6AN male adapter fitting. However, various 8AN ORB adapter fittings can be purchased separately HERE

VENT-8AN MALE: The external "VENT" port is tapped with 1-1/16"-12 threads making it compatible with all 12AN ORB fittings. The FCST comes standard with 20-0435 which uses a common 8AN male outlet fitting for standard fuel filling. However, 20-0462 can be purchased separately with a 12AN male fitting for quick fill dry break systems.

FCST Parts Required

A fuel cell is not included with the FCST. If you would like a fully assembled FCST in a Radium Fuel Cell, go HERE. The fuel cell MUST use a 6x10, 24-bolt fill plate flange. The distance from the outer top face to the internal botton face cannot be any shorter than 7.6" (193mm). The distance from the top of the fuel cell to the bottom of the lift pump filter (lowest point of the kit) is adjustable. However, if the fuel cell is deeper than 10 inches, purchase this Lift Pump Extension.

If you do not currently have a 6-bolt (2.18" B.C.) filler, these Radium Fill Neck options can be used for direct or remote filling.

A hose and/or filter must be connected to the "VENT" port fitting. For compatible vent kits and more information on how these are plumbed and routed, go HERE.

FCST Optional Upgrades

The FCST comes standard with a fuel level sender block off plate. However, SAE fuel level senders of various lengths can be purchased separately HERE.

For the ultimate in fuel starvation protection, the lift pump can be placed into this Radium Collector Box.


For information on FIA Certification, go HERE.

Below is a quick demonstration of how a basic fuel surge tank system works.


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