Radium Updates the FCST for 2019
The Radium Engineering Fuel Cell Surge Tank (FCST) was a revolutionary product when it was first released in the Fall of 2014. Since then, the FCST has found it's way into many successful competition vehicles. The ability for it to eliminate fuel starvation during aggressive driving has made the FCST ideal for any motorsports application. It has become the go-to standard for professional drift teams and has proven itself time and again in many race and street applications worldwide. The Radium FCST continues to be the ONLY true multi-pump dual-chamber surge tank solution that installs INSIDE a competition fuel cell. 
The four year anniversary was a chance to update the design and make some small changes that will improve the functionality and reliability of the FCST. 


The FCST has previously used two circular electrical connectors, as shown below. One for the lift pump and one for the primary pumps.

The new version has eliminated the circular connectors and associated flying-lead harnesses and replaced them with individual stainless steel electrical stud connections, as shown below.

The design of these electrical studs has proven reliable through in-house testing and over the past few years on Radium's line of in-tank fuel pump hangers. The studs offer easy and inexpensive serviceability, easy troubleshooting and the ability to handle very high current loads. They create a hermetic seal with the top plate that is impervious to all fuel types. Another added benefit is the low-profile nature of the studs and the connecting wires, which allows direct and uncluttered wire routing. Crimp-on ring terminals and shrink tubing are included with the FCST.


The previous version of the FCST used individual 6AN male fitting for the pump outlets that feed the engine, as shown in the picture below. If less than three pumps were selected by the customer, a plug was used on the remaining port(s).

This setup required the use of hoses and T or Y fittings to combine the outputs together into a single line, creating plumbing complexity.
The new version utilizes a single output for all pumps. The top plate outlet port is female threaded for 10AN ORB and a 10AN ORB to 8AN male adapter is included by default (shown) for all configurations. Other compatible 10AN ORB adapters can be found HERE and purchased separately.

The merging of the pumps is done internally. Block-off plugs are included for configurations that require less than three primary pumps. All of the fuel pumps that Radium offers with the FCST have built-in check valves to prevent back-flow. This allows the pumps to turned on/off at different times based on engine fuel demand.


The vent fitting on the FCST plate plays a crucial roll of allowing air out when fuel is entering the fuel cell during filling, it also keeps the cell at atmospheric pressure.  Previously, the vent port was a 8AN ORB female port. The new version has been changed to a 12AN ORB female port, shown below. 

The new larger vent port allows air to escape faster for quick filling applications. This larger vent port also meant a new roll-over protection valve needed to be designed. A roll-over protection valve installs into the vent port and prevents fuel loss should the vehicle ever become inverted. It was decided that the new valve should not only offer roll-over protection, it should also prevent fuel loss in the event the fuel cell is over-filled. 

The Dynamic Safety Valve (DSV) was created (shown above) and performs two functions. First, it shuts off flow if inverted. And second, it contains a floating ball that seals the vent should the fuel level rise high enough, preventing fuel loss through the vent port. Another advantage to the new DSV compared to the previous roll-over protection valve is that it can be removed easily without the need to separate the top plate from the fuel cell bladder. The DSV is included by default with every FCST and retains the same 8AN male for vent hose attachment. This valve is to be used with standard filling only (not quick fill dry-break systems). 
Radium will introduce a high-flow DSV variation that will be suitable for quick-fill systems at a later date.


The machining of the underside of the FCST top plate was modified to better manage the flow of fuel into and around the surge tank. The return fuel now passes through a diverter that directs it tangentially into the surge tank canister, reducing fuel agitation and creating a true "swirl pot". Fuel from the lift pump also enters the surge tank tangentially for the same reasons.

  • The new FCST plate is still the same 6" x 10" 24-bolt size and will work in all previous applications
  • The same fuel pumps as before are still offered
  • The fill neck and level sender interfaces remain unchanged
  • Still E85 compatible
  • The FCST can still be ordered by itself or packaged with a competition fuel cell
  • Pricing remains unchanged

Additional Information
Click HERE to learn more about the fuel cells Radium offers
Click HERE to watch an independent fuel cell installation video
Click HERE for a fuel cell ordering guide
New Products for the 2015+ Subaru WRX
Radium Engineering has just released a range of products for the 2015+ Subaru WRX with the FA20 engine. These products are designed to improve the driveability and performance of the WRX without sacrificing reliability. 
The WRX version of the FA20 engine is equipped with tumble generator valves to assist with emissions during cold engine temperatures. These devices also impede air flow in the intake manifold runners. By eliminating the obstruction, a clear airflow path is established. The Radium Engineering TGV deletes are machined from 6061 aluminum and anodized green or black. Installation is quick and easy (compared to EJ-series engines) and can be performed in about 30 minutes.

The tumble generator valves are an emissions control device, and as such should be removed only for vehicle operating off-highway. It is also recommended that a complimentary engine management tune be implemented to take full advantage of the TGV deletes. No permanent modifications to the vehicle are necessary to install the TGV delete kit.

Even with low mileage modern cars, oil accumulation in the air intake stream can happen. The Subaru FA20 engine places the turbocharger down low, in front of the engine. This leads to oil from the PCV system collecting in the turbo air inlet pipe, down near the turbocharger. This oil is result of blow by coming through the crankcase ventilation system. This oil will eventually be digested by the turbocharger and deposited through the charge piping and can even result in blue smoke from the tailpipe. 

The Radium Engineering Dual Catch Can Kit intercepts the PCV gasses and traps the oil and other pollutants before they can make it back into the intake stream. The kit tucks in perfectly on the RH side of the engine bay next to the ABS module, mounts to existing engine bay fasteners and requiring no relocating of engine bay components. The front catch can intercepts the crank case vent hose that connects to the turbo inlet pipe, keeping oil out of the turbo inlet. The rear catch can intercepts the PCV hose coming off the block and going to the intake manifold, keeping oil out of the intake manifold. The catch cans are designed to withstand boost pressure and are sealed, so direct connection to the intake manifold, even with forced induction, is OK.
This kit is perfect for a street driven car experiencing mild amounts of blow-by.

For more race-centered applications, or cars with built high-powered engines, more oil blow by is usually experienced, often overwhelming the volume of the standard Radium catch cans.  For these applications Radium Engineering applied it's Air/Oil separator to the FA20 engine.

The Air/Oil Separator functions in a similar manner to the catch cans, however, the big difference is that oil is returned back to the engine, rather than stored in the catch can. But catch cans do not only catch oil, they also catch water condensation and it is not ideal to have this water mix with the oil, then return it to the engine. To remedy this, the Radium AOS is heated with engine coolant. This keeps the water vapor from condensing and mixing with the oil.

Engine coolant is plumbed through the bottom plate of the AOS.

Another important aspect of the AOS is that it does away with the function of the PCV valve. Instead, the engine is allowed to breathe freely from both the crank case vent port (at the front of the engine) and the PCV valve port (under intake manifold). The PCV valve is removed from the engine block and replaced with Radium's custom made PCV delete fitting, shown below.

This fitting screws into the block and adapts to a -10AN male. It is straight through, with no check valve or any other device built in. This allows maximum ventilation to the AOS through this port. This is also the path for collected oil to drain back to the engine block.
With both engine ports breathing freely into the AOS, the AOS needs to be vented to atmospheric pressure. This is done by routing the AOS side port back to the turbo inlet pipe. This creates a closed-loop system.
The AOS was designed to mount in the engine bay near the brake master cylinder (for LHD vehicles only) using the Radium Master Cylinder Brace for the 2015+ WRX as the mounting point.

The master cylinder brace is a simple and effective way to reduce firewall flex resulting from brake pedal pressure.It is machined from 6061 aluminum and mounts to the strut tower using pre-existing threaded holes. Clearly visible in the photo below are the three threaded holes in the brace where the AOS bracket attaches.  The brace is sold as an individual item, or as part of the AOS kit.

While installing an AOS kit can be done with the stock fuel feed hose, Radium offers an aftermarket fuel feed hose replacement that cleans up the fuel routing and offers better clearance with the AOS. The hose has a PTFE core that is compatible with all fuel types and also features machine-crimped end fittings.

For all of the products shown here, and a few more, please click HERE.
New Product Release: Subaru AOS and Oil Catch Cans
It is well known that Subaru engines are prone to excessive blow-by, creating a collection of oil and other contaminants in the intake system and intercooler. Do you ever see blue smoke in the rear view mirror? This is typically the contaminants getting burned through the combustion process. 

Shown above is a Subaru valve cover vent crossover pipe that is almost completely clogged with oil residue and carbon build-up.

Radium Engineering Solutions

1. Dual Catch Can Kit
For street driven or lightly modified vehicles, a simple oil catch can system will often do the trick. Radium Engineering has utilized its compact catch cans to created an integrated package for installation into various 2002-2014 Subaru engine bays. The catch cans are designed to collect and retain the oil and other contaminants, preventing them from being cycled back through the engine's air intake and intercooler system.
                                              CLICK HERE to learn more about the Radium Engineering catch cans.

The Subaru Dual Catch Can kit mounts on the RH stut tower and includes two catch cans. The forward catch can is plumbed in-line with the valve cover crankcase vents. This catch can filters and cleans the gasses before they are drawn into the intake pipe. It is responsible for keeping blow-by oil and other pollutants out of the turbo inlet pipe, turbocharger, and intercooler during high engine loads. The rear catch can intercepts the vacuum hose between the intake manifold and PCV valve. This catch can keeps oil and sludge out of the intake manifold. It functions when the engine is in vacuum and the PCV valve is open. The PCV system dynamically changes depending on the throttle body position. See below:

As shown above, when the throttle is closed, the one-way PCV "check" valve opens.

When the throttle is open, the PCV valve closes and all the crank venting is happening through the valve cover vents. The air being sucked in by the turbocharger helps create negative pressure in the intake pipe, which then results in a mild vacuum to the crankcase vent catch can, to help draw out the gasses. In all engine load scenarios, the PCV system promotes negative pressure in the crankcase that can extend engine life.

With the kit mounted in the area of the turbocharger, protection from heat is accomplished with a modular heat shield (shown above). This is necessary to keep the temperature of the catch cans down and help promote condensation of water vapor inside the catch cans where it is collected along with oil and unburnt fuel. The catch cans should be periodically checked using the dipsticks and drained as needed. To dispose the fluid, simply remove the 4 heat shield mounting bolts with a 3mm Allen wrench. The lower half of the catch can bodies unscrew for easy servicing. Always properly dispose of the contaminants. Do not pour catch can contents back into the engine oil.

Click here for the Subaru Dual Catch Can Kit product page

2. Air Oil Separator (AOS) Kit
With a higher engine power output comes an increase in oil circulating through the crankcase ventilation system. Horizontally opposed engines, in particular, expel an excessive amount of oil through the ventilation system. In extreme cases, this may overwhelm the capacity of the standard sized catch cans during long track sessions. Instead of using a large reservoir to retain all the collected contaminants, the oil can be returned to the pan. However, this process must take into account several considerations in order to function properly. 

Shown above is the Radium Engineering Air Oil Separator (AOS). The AOS is built on the foundation of the Radium Competition Catch Can, but with a new specifically designed bottom plate. Full CNC construction, sealed with O-rings and anodized. The AOS still features all of the same oil baffling media found in the competition catch cans. However, instead of collecting oil, the AOS drains back to the engine through the large baffled -10AN ORB bottom port, shown above.

The bottom plate not only features a large oil return port, it also functions as a heater to prevent water from condensing inside the can. The heater is fed by coolant circulating to/from the engine. The cooling fins, shown above, increase the effective surface area of the heating element. Also, if any water were to make it's way into the canister, it would be trapped underneath the lower density oil in the bottom trench. The center port baffle provides a layer of protection to keep debris from enterning the crankcase. 

For AOS crankcase plumbing, the valve cover vents are routed into the top inlet where the stainless steel condensing material separates the oil from the gasses. The PCV valve is removed and the system is no longer hooked up to the intake manifold (vacuum). The crankcase port in the center of the block (green arrows) is now routed directly to the AOS bottom port with a large diameter -12AN (3/4" ID) hose. The filtered liquid oil is collected at the bottom of the AOS and is drawn into the oil pan through the 3/4" hose. Meanwhile, the clean crankcase air can either be vented to atmosphere (VTA) or recirculated to the turbo air inlet pipe (see instructions for details) out of the side port of the AOS.

The AOS completely disassembles for easy servicing when needed, as shown above. 

Because of limited vertical clearance, special low-profile banjo style fittings were developed for the Subaru AOS kit. These fittings are super compact, yet high flowing. They are machined from aluminum and anodized.

Radium installation kits include all necessary parts for an easy bolt-in process.

Shown above is the AOS system fully assembled with a Subaru specific mounting bracket and fittings.

When installed, the valve cover vent lines "Y" together and are plumbed into the top port of the AOS can. The side port is used as the vent to atmosphere (VTA), or it can be routed to the turbo inlet pipe for a closed system. The bottom port of the AOS can is plumbed with a 3/4" hose to the crankcase vent port on top of the block. This line acts as a way for crankcase gasses to enter the AOS, but also functions as the path for oil to return back to the oil pan.
Click here for the Subaru AOS Kit product page

Both Dual Catch Can and AOS kits are available for the Subaru WRX, WRX STi and Forester XT in the 2002-2014 model year range.

Contact info@radiumauto.com with any questions.

An Unexpected RX-7 Sleeper

We do not feature cars on our blog often, but when we come across something unique, we find it hard to resist. The car featured is owned by a long time friend of ours and has been a project in the works for a few years. It was put together slowly, with care, and everything was done "the hard way" in an effort to make it the very best that it can be. Assembly, fabrication, wiring, etc. was done in a cramped garage in Portland, Oregon. No high dollar tools or 2 post lifts were used. We are talking jack stands with poor lighting.  All custom parts were hand formed using small tools and whatever Harbor Freight had that could do the job. It is amazing that something so clean, unique, dialed, and fun could emerge from that garage.

The car is a 1985 Mazda RX-7. A very clean example that was bought locally and used as the host for a wild engine transplant. It sits on Enkei Bortex F17x7/R17x8 wheels with Toyo Proxes 4 tires.

The exterior is dent free and all the plastic trim is in perfect condition. Notice the custom decal that was made...

The front and rear brakes are directly off a Mistubish Evo 8. Not just the calipers, the complete brake system including the vacuum booster, brake master cylinder, and rotors. The calipers attach using custom fabricated brackets.  Each Brembo caliper was completely disassmbled, sand blasted, then powder coated silver and rebuilt by the owner. All new stainless steel hard lines were bent up by hand.

The super clean interior of the car keeps the totally 80's RX-7 vibe. Much effort went into making sure all factory gauges worked correctly with the new engine and stand-alone EMS. More on that part later. The seats are from a Lotus Elise and are mounted on custom fabricated brackets.

The driver's door panel features a unique touch. The owner hand stitched a new panel and while he was at it, he inset an aluminum "Franken Speed" plaque to play on the Frankenstein engine swap idea.

The underside is just as spotless and just as sorted as everything else. Poly bushings, aftermarket swaybars, Koni shocks, Ground Control coilovers, etc are all put to use keeping the chassis in check. All components were cleaned, powder coated and reassembled with fresh nuts and bolts. The rear differential is a limited slip unit from a GSL-SE, rebuilt by the owner. The 3" stainless steel mandrel bent exhaust was hand fabricated by the owner and exits through a discrete black Vibrant muffler.

A Nissan 240sx rack and pinion with power steering was retrofitted into the front of the car and is fully functional.

Now for the really fun part. When the forward hinged hood is openend, there is something that catches everyone off guard.  What is it?  Is that a....Nissan engine....? Why yes it is. A fully built turbocharged Nissan KA24DE. The short block was machined .040" over and put together using Wiseco pistons and Eagle rods and ARP fasteners. The head underwent hours and hours of hand porting (by the owner in his cramped garage) and received Brian Crower valve springs and oversized valves. The cams and titanium retainers are also from BC. The head was put back on to the block using large 11mm ARP studs.

Supplying boost is a Garrett GTX3071R turbocharger that sits on a custom fabricated stainless steel Schedule 40 tubular manifold (made by the owner) and uses a water cooled Tial 44mm external wastegate fully plumbed into the cooling system using stainless steel hard lines.

The owner sanded down the TWIN CAM 16 VALVE  lettering on the stock valve cover then welded on a laser cut plaque and sanded that smooth. The valve cover was then airbrushed and clear coated. Custom hand-bent stainless steel fuel lines feed the modified AEM fuel rail and ID 1000 injectors. Notice the hand made gussets on the intake runners, those aren't stock.

The aluminum intercooler piping was also all hand fabricated and feeds the Xcessive Manufacturing intake manifold and Nissan/Infiniti Q45 throttle body. Maybe this is a good time to mention the car has working cruise control. The intercooler is a modified unit from a Evo 8 and sits stealthly behind the bumper and under the car. The engine also features an Xcessive Manufacturing cast aluminum large sump oil pan, which incorporates their windage tray and crank scraper.

The owner hand-made the strut tower brace from scratch as well. Under the engine is a matching chassis brace.

Built into the strut brace is a a hydraulic engine torque damper, you would not even see it if you weren't looking. The car uses an OEM RX-7 radiator and an electric fan. The car was converted from distributor ignition to individual coils using GM LS2 coils, mounted out of site in the cowl by the windscreen wiper linkage.

A set of Radium Engineering oil catch cans were used to tackle the blow by gasses present in any turbo engine.

A Radium fuel surge tank and first generation fuel pressure regulator were also used. Notice the custom hand bent stainless steel hard line feeding the engine bay mounted surge tank. Those stainless hardlines run the length of the car.

The Infiniti Q45 remote-mount throttle body cable pulley system was adapted and incorporates electronic cruise control.

The engine is controlled with an AEM Series 2 EMS, tuned by John Reed Racing. The car makes 400whp at 16psi of boost on pump gas (92 octane). The plan is to eventually run race gas in an attempt to hit the 500whp mark.

The owner has driven the car to Southern California and back and drives locally on a regular basis. The brakes work very well and are quiet and smooth with a firm pedal. Power comes on smoothly and linear all the way to redline. It idles perfect, starts up instantly, and overall is a pleasure to drive on the street. Doing everything the hard way seems to have paid off on this build.

See more pictures at our Flickr Gallery HERE.

New Product Release: FST-R....Two parts in one!

Radium is proud to release the first ever fuel pressure regulated surge tank. The innovative FST-R (Fuel Surge Tank - Regulated) is a fuel surge tank that houses a single internal fuel pump and has a fuel pressure regulator integrated in the top cap. This revolutionary idea eliminates the need for an external regulator along with the extra hoses and fittings associated with it.

This setup offers multiple benefits:
1. Reduced overall system cost
2. Reduced fittings resulting in less potential leak/failure points
3. Reduced hoses resulting in a lighter FST system
4. Reduced fuel temperature from the elimination of fuel returning from the engine bay
4. Quicker, easier, and cleaner installation

The FST-R is machined from 6061 Aluminum and like all Radium Engineering products, it is fully anodized and compatible with all fuel types.

The integrated fuel pressure regulator has all the features of a market-leading regulator. The output pressure is adjustable using the screw on the top cap. It is also capable of 1:1 vacuum reference by securing a vacuum hose to the nipple on the top.

The clean and compact package does not add significant size to the Radium fuel surge tank. The regulated output port is located on the side of the cap.

Shown above with an AEM 50-1200 E85 compatible fuel pump.

Inside the surge tank, many of the popular fuel pumps we currently supply can be used including: AEM, Walbro, Deatschwerks, and Aeromotive. At this time, the FST-R can only hold a single fuel pump. If a dual pump surge tank is needed, please see our other surge tank offerings:

The regulator features interchangeable orifice sizes to match the output of different pumps.

When purchased with a pump, the FST-R will come fully assembled and pressure tested. Radium assembles the FST-R with the properly sized orifice for the pump. Two extra orifices are provided should the user ever decide to change pump.

A fuel pressure gauge/sensor should be installed on the high pressure output line (or fuel rail) to adjust the regulator. The Radium Fuel Pressure Gauge is perfect for this duty.

This FST-R works by converting to a returnless dead-end system. Unlike a "returning" fuel system, fuel sent to the fuel rail(s) is not returned back to the fuel tank. See the diagram below which shows the difference between a returning and a dead-end system.

One of the benefits of a dead-end system is that fuel heated by the engine is not circulated back to the surge tank or main fuel tank. This keeps heat out of the fuel system. Most modern vehciles use a dead-end fuel system for this reason and for improved EVAP emissions.

Is fuel flow restricted or fuel delivery "uneven" in a dead-end system? See the picture below of Dean Kearney's Formula Drift Viper which utilizes a dead-end system. Notice the FPR mounted in the image. This car runs a single -8AN hose up to feed the 1,000+Hp engine.

Radium also has extensive experience with E46 BMW fuel systems for S54 (inline-6) engines making over 1,000whp. BMW is one of many manufacturers that use dead-end fuel systems.  Radium also successfully runs a dead-end system on their turbocharged Lotus Elise. 

Radium's Lotus Elise running a prototype FST-R and dead-end fuel system. The OEM Lotus (and Toyota) fuel system is returnless as well.

Please feel free to contact Radium Engineering with any questions about your fuel system needs: info@radiumauto.com.

The RADIUM FST-R is in stock and ready to ship, see details here:

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