SKU: 20-1989
Radium Engineering 20-1989 Extension Kit for FCST-X 3.7in 1.2L: Boost Fuel Surge Tank Capacity for Reliable Racing Performance
The Radium Engineering 20-1989 Extension Kit for FCST-X 3.7in 1.2L stands out as the direct solution for racers facing fuel delivery challenges, adding 1.2 liters of extra volume to your FCST-X fuel surge tank while repositioning one-way fill valves lower for enhanced protection against starvation during low-fuel cornering or hard acceleration.
This design ensures steady fuel pressure to your high-performance EFI engine, outperforming basic surge tanks by extending run times and reducing the risk of lean conditions that can sideline your build. Drivers report consistent power delivery across demanding track sessions, making this kit the practical pick for anyone pushing limits in competition setups over generic extensions that fall short on integration and durability.
Crafted from CNC-machined anodized aluminum, the 20-1989 kit installs cleanly between the FCST-X top plate and existing canister, raising the overall height by 3.7 inches for that critical capacity gain without altering your fuel cell’s footprint.
It demands a minimum fuel cell depth of 10.8 inches to fit properly, pairing seamlessly with Radium’s deeper cells for setups where every drop counts. This extension transforms your surge tank into a more robust system, handling aggressive driving better than stock configurations by trapping fuel around pumps longer and venting efficiently to prevent surges.
What’s Included in Your 20-1989 Purchase
Every Radium Engineering 20-1989 Extension Kit ships complete with these components for straightforward end-user assembly:
- Anodized aluminum extension canister (adds the 1.2L volume)
- Extended stainless steel pump bracket (replaces the standard one for secure fit)
- Large ID fuel pump tubing (for high-flow pump integration)
- Small ID fuel pump tubing (for precise secondary lines)
- Submersible fuel hose (ensures reliable submersion in the cell)
- Stainless steel hardware kit (bolts, clamps, and fittings for mounting)
Note: For FCST-X model 20-1991-00 equipped with Bosch BR540 or DeatschWerks DW400 pumps, add Radium part number 14-0691 adapter fittings (quantity based on pump count).
Vehicle Fitment Details
The 20-1989 Extension Kit fits universally across EFI racing vehicles using compatible Radium FCST-X surge tanks in deep fuel cells, eliminating starvation in high-G turns or low-tank scenarios common to track and drag applications. Specific compatibility includes:
- FCST-X Surge Tank Models: 20-1990-00, 20-1990-01, 20-1990-02, 20-1990-03; 20-1991-00 (with 14-0691 adapters) 20-1992-00, 20-1992-01, 20-1992-02, 20-1992-03
- Compatible Radium Fuel Cells: R14A (14-gallon, part 20-0614); R22A (22-gallon, part 20-0622) or any FCST-X-ready cell with at least 10.8 inches depth
- Vehicle Applications: Universal for performance-modified street and race cars, including Subaru WRX/STI (2002+), Nissan 350Z/G35 (2003+), Mitsubishi Evo (2003+), and custom builds in deeper aftermarket cells ideal for setups like the Nissan Skyline GT-R (1989-2002) or Toyota Supra (1993-1998) with upgraded tanks.
- Incompatible With: Shallow Radium cells like R06A, R10A, R11A; non-FCST-X surge tanks or cells under 10.8 inches deep
Part weight and shipping box dimensions are not listed by the manufacturer, but the compact design keeps packaging efficient for standard ground shipping.
The Radium Engineering 20-1989 delivers proven reliability that keeps you on track longer than alternatives, securing it as the go-to upgrade for serious fuel system builds.
Order now to maintain that edge in every pass.





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