An Introduction to Fuel Cells and Certification

Radium Engineering offers top of the line fuel delivery solutions for the motorsports market, including fuel cells. Many consider fuel cells as a simple metal container, when in fact a proper motorsports fuel cell is more complex. A basic aluminum, stainless, or mild steel container is more susceptible to fracturing in the event of a collision. This would create leak(s) and could lead to a dangerous fire situation. Even a minor fender bender or the flexing of the chassis during hard driving could create enough force to distort and crack the metal container. Fuel weighs 6.3~6.6 lbs per gallon. With a 14 gallon fuel cell that is 90 lbs of fuel sloshing, flexing the walls, and applying strain to the welds. When that much weight is subject to g-loading, the resulting forces are very large and can damage a poorly designed metal container. Furthermore, the thermal expansion created by elevated fuel, exhaust, and ambient temperatures put excessive stress on the can. Lastly, chemical compatibility, weld quality, and corrosion are concerns when using a metal container for fuel storage. In short, Radium Engineering does not recommend these types of fuel containers on performance vehicles.

Fuel cells used in motorsport racing often require FiA or SFI certification to ensure safety requirements are met. The guide below helps explain how a fuel cell works and why certification is necessary.

What is a Fuel Cell?
As shown, competition-grade fuel cells are generally comprised of three components: the outer shell (enclosure or can), the bladder (where fuel resides) and the foam baffling.
Radium Engineering fuel cell enclosures are made from lightweight aluminum, but other brands may use steel or other materials. The enclosure is the first part of the fuel cell to absorb damage and help prevent a catastrophe. This layer is similar to the construction of a helmet. The outer enclosure aids in safety but is not the most critical part. FIA and SFI specifications do not cover the outer can material alloy or thickness, only the internal bladder. Other governing bodies require a certain outer can thickness. For instance, SCCA requires a fully enveloped enclosure comprised of 0.036” steel or 0.059” aluminum.
The fuel cell bladder contains the fuel and protects from spills. The bladder must be resilient against impacts, punctures, and tears. The material also needs to be flexible enough to prevent cracking or fuel leakage in the case of impact and thermal expansion. These requirements have led to the development of different high-tech bladder materials used in the industry. Radium Engineering chose to only focus on molded polymer bladders as they have the best chemical compatibility and still meet all the structural testing requirements put forth by SFI and FiA.

The foam baffling is essentially a large open-cell sponge inside the fuel cell and serves several purposes. If catastrophic failure were to happen, this porous foam helps absorb the fuel and prevent an explosion. It also suppresses explosion potential by preventing fuel vapor buildup inside the cell. As an added benefit, it helps prevent fuel slosh which can cause fuel starvation. Fuel cell foam is a wear part and should be inspected periodically to ensure integrity. Loss of elasticity or degradation of any kind are signs the foam should be replaced.

What is FiA?
The Federation Internationale de l’Automobile (FiA) has been around for over a century. It is an international organization that promotes road safety around the world and creates rules and regulation governing all forms of motorsports. FIA's most prominent role is licensing and sanctioning of Formula One, World Endurance Championship, World Rally Championship and various forms of sports car and touring car racing.
For the safety of the driver, FiA homologation (certification) is required in many forms of racing. This covers many safety related components including fuel cell bladders. FiA has a few distinct classifications regarding fuel bladders: FT3, FT3.5, and FT5. There are other standards required by other sanctioning bodies, but FiA is the gold standard.
All of the ratings clearly define the requirements for materials, construction, and testing. The only difference between the ratings is the strength of the bladder material. All tests utilize the same procedures but the levels of certification are based on test results. FT3 is the first level requiring the lowest minimums while FT5 requires the highest. For example, Formula-1 requires FT5, but SCCA requires FT3 (although FT3.5 and FT5 are also acceptable.) Check with your sanctioning body to see what requirements your vehicle must meet.

What is SFI?
The SFI Foundation, Inc. (SFI) is a non-profit organization established to issue and administer standards for the quality assurance of specialty performance and racing equipment. The SFI Foundation has served the automotive aftermarket and the motorsports industry since 1978. Their service to the industry is a system of developing and administering various standards, certifications and testing criteria for use in motorsports.

Like FiA, SFI has a few different specification levels. SFI Spec 28.1 is the lowet and is for polymer foam-filled fuel cells. SFI Spec 28.2 is for crash resistant fuel cells and SFI Spec 28.3 is for competition fuel cells. Radium Engineering RA-Series fuel cells are certified SFI Spec 28.3.

Testing and Quality Control
Both SFI and FiA evaluate the bladder's structural integrity and perform rigorous mechanical testing including: tear, puncture, tensile, and compression.

Radium Engineering takes this process one step further. Before they leave our facility, every individual bladder is quality control tested as shown above.

Fuel cell certification expires 5 years after the date of manufacture. Check the label on the fuel cell bladder for the expiration date.

Heat, UV light, vibrations, and fuel are all factors that contribute to elastomers breaking down in a bladder. Water and alcohol fuels also can cause deterioration. Fortunately, all Radium Engineering bladders are made from a special polymer that are not as susceptible to chemical deterioration like coated fabric bladder variations (shown below) that are glued together.

However, all fuel cell bladders should be regularly inspected and replaced as needed.

Fuel cells generally require some level of maintenance. Regular maintenance ensures the fuel cell will last the full 5 years or longer in non-certified applications.
Maintenance tips: The fuel cell should be drained whenever the vehicle is stored for a long period of time. This will extend the life of the fuel cell. Alcohol is most damaging to the foam. Proper care of this part of the cell is crucial for maintenance. Foam breaks down over time and particles can clog the fuel system so it is imperative to use pre pump filtration. It is ideal to periodically replace the foam in the cell to increase cell longevity. Always follow the guidelines included with every Radium Engineering fuel cell.
Inspection: While replacing the foam, always inspect the bladder for any signs of wear, damage or degradation.

To conclude, metal box style "fuel cells" are prevalant on the discount market, however, they offer little to no engineering in regard to safety. The added cost of a certified bladder-style fuel cell can be easily justified in the event of a collision or other disaster.

Testing the ID Brushless Pump
NOTE: Radium Engineering is not a dealer of Injector Dynamics parts. Contact Injector Dynamics for more details about this pump system.

Electric motors continue to evolve and become increasingly more efficient. A significant improvement comes from brushless motor design which operates in a different manner than a standard DC brushed motor. For more details on how brushless motors work, CLICK HERE.
It is not uncommon to find OEM fuel pumps in modern high performance vehicle using brushless technology. They inherently draw less current (less heat) without sacrificing flow. But unlike traditional brushed variations, these pumps require a complex fuel controller to operate.

Dating back to 2013, Radium has embraced brushless pump technology. Fuel surge tanks utilizing both OEM brushless pumps (above) and aftermarket (below) have been available for several years. These have had limited interest due to the lack of affordable high-quality brushless controllers on the market. That is quickly changing.

For some time, the aftermarket company Injector Dynamics has been developing a state-of-the-art fuel controller for OEM brushless pumps from Bosch and Ti Automotive, shown below. 

The same Ti Automotive E5LM pump (found in the Bugatti Veyron) proved to have most potential. In it's most primitive state using the simple Ti Automotive BKS1000 controller, we've tested the E5LM pump at 13.5V to flow 590LPH at 43.5psi. See the tech article HERE.

We recently received a beta unit (above) from Injector Dynamics for testing. What you see is a high quality anodized aluminum control unit, Ti Automotive E5LM pump, stainless steel hardware, wire leads and associated components.

The fuel controller has 2 large cooling fans as well as diagnostic LEDs and a reset button for troubleshooting up to 11 error codes.

The Injector Dynamics BPC1100 system is RPM based and can run the pump at constant speed, MAP based speed, or PWM based speed using adjustable potentiometers (shown above). It is CAN equipped and has a pump speed output for ECU data logging. 

As expected, the controller is larger than others (Dim: 236mm x 160mm x 72mm). For a comparison, the Ti Automotive BKS1000 brushless controller is shown in the left foreground above.

To match all the features and capabilities of this unit, proper electrical is critical. It is mandated that a 125A fuse is used with 2AWG wire for the main power and ground connections. Shown above is an example of the minimum wiring to connect the ID BPC1100 to a Nissan R35 GT-R.

The Radium Engineering flow bench was set up using a MPR to regulate fuel pressure. The fluid used in the test has a specific gravity of 0.77 and flowed through a 6u Microglass Fuel Filter. Shown below are actual recorded numbers from the test bench instruments.

The graph above illustrates current draw at full output and various pressures with a 13.54V input. In extreme situations (8V input and 130psi @ 1100LPH) the current draw can get up to 95A. But don't forget, it's doing more than 5 times the work load as compared to a normal controller in those conditions.

As depicted above, current draw is only 5.5A in typical conditions (400LPH, 3BAR, 13.5V). 

The graph shown above is NOT a misprint. This system can flow over 1100LPH at ANY pressure up to 150psi.

With all of its features and potential, this system from Injector Dynamics is very impressive. At maximum settings, the pump could easily output over 1100lph.

It's unique in that the controller will always hit the target flow, even when conditions like fuel pressure and voltage vary. The only difference you'll notice is the current draw required to make it happen will change. When you compare this system to many others, it doesn't seem possible. This system gives the user the ability to specify their flow rate at any pressure, something not possible with a brushed fuel pump.

We predict that this system could replace the need for mechanical fuel pumps and could even take the place of multiple brushed pump setups as the norm. At this time, we are unsure when it will be available or how much it will cost. But, expect to get what you paid for.

Furthermore, this system can be used in many current Radium Engineering products. As long as the description states "...Ti Automotive E5LM...", the BPC1100 brushless system is compatible.
For more information on pricing and availability, please contact Injector Dynamics.


All About Fuel Pumps, Updated January 2021

At Radium Engineering we design our surge tanks and fuel pump hangers around popular aftermarket fuel pumps from Walbro (aka Ti Automotive) and AEM. We have chosen to offer the highest performing pumps from the most reputable companies.
This article will describe each pump and provide information so you can choose the right pump (or pumps) for your application.

Lets start with our most popular offering, the Walbro F90000-series pumps, officially called Ti Automotive 39/50 DCSS pumps. These gas/E85 compatible pumps have a stepped body and come in different flow rates depending on part number.
These are tricky to talk about because many people use the unofficial slang names given to these pumps, such as the "Hellcat pump" or the "Walbro 450" etc. These names rarely have anything to do with the actual flow rate of the pump and often just cause confusion. Here at Radium Engineering we call these pumps by their official F90000... part number, stamped right on the side of them, as shown below.
Ti Automotive has released many F90000-series pumps to the aftermarket over the years, but we are only going to focus on the three most popular: F90000274, F90000285 and F90000295

All of the F90000-series pumps have the same physical dimensions and same electrical connector, so they can be interchanged with each other in Radium products.

The "274" and "285 both have internal check valves, so they can be staged when using more than one in a surge tank or hanger. The "295" does not have a check valve (hence the higher flow) so line pressure immediatly drops when it turns off and it cannot be staged with other pumps, but it works great as a lift pump.
Radium Engineering only offers the F90000274 pre-assembled into products. If you would like to use the F90000285 or F90000295, select the Radium product version "pumps not included" and purchase the pumps you want to use separately.
In-house back-top-back testing of the three F90000-series pumps here at Radium Engineering resulted in the following performance curve:

The F90000285 outflows the F90000274 by about 8%, but requires about 15% more electrical current (more heat!). So only use the F9000285 if you absolutely have to in order to avoid excess heat going into the fuel.
Note that our test numbers are not a direct match to what TI Automotive advertises. This is due to different testing methods and conditions. Also, as pumps wear in, they generally increase in flow rate. This chart does provide a good back-to-back comparison of the pumps though.

The chart above shows how much current each pump uses when operating at 13.5VDC. The F9000285 is drawing considereably more current than the other pumps, this is where it's higher flow rate is coming from. Plan your wiring accordingly.

These pumps have a pressure relief valve setting of about 110-112 psi.  This means that if fuel pressure exceeds this value, a valve will open on the pump and let out excess fuel to keep the pump from hurting itself.

Advanced Engine Management (AEM) has been around a long time and is very well known in the aftermarket and motorsports industry. Their fuel pumps offer a lot of performance and value. The pumps are made to AEM's exact specifications, which are the result of many hours of R&D and countless hours of testing.
We are often asked "Because it is an E85 pump, does it work with gasoline?"  YES! It is compatible with gasoline and alcohol fuels. It even states this right on the side of the pump. These pumps flow 340LPH at 40psi and come in two heights. The size of these pumps mimics popular OEM fuel pumps sizing, so they can swapped into many cars without much work.

This tried and true option from Walbro is economical and effective. These pumps are great for vehicles with lower power output. This pump draws less electrical current, which helps keep fuel temps lower. However, this pump is not quiet. It is also not officially rated for use with E85, however historical data has shown that it does work fine with alternative fuels.

There is a new king on the block. This brushless pump system is a great option for high power vehicles. Brushless pumps creates a lot of flow without using much electrical power. This helps keep fuel temps and electrical load on the alternator low. Because of the popularity of this option, Radium has been intgrating this pump into new product designs.
A brushless pump always needs a controller. In this case, the controller is a separeate device that sits outside the fuel tank. Four wires connect the controller to the pump. This controller is not programmable in any way, which keeps its complexity and price down. Power is fed into the controller through the red and black wires.

The pump itlsef is called an E5LM. This was previously used in some supercars and high-end SUVs. It is the same 39mm diameter as the other pumps on this page, but it is quite a bit longer. This makes packaging difficult and requires unique designs for many Radium products.

1. The outlet of the pump DOES NOT HAVE A CHECK VALVE! So you must be careful if planning to stage this with other pumps.
2. The system is only sold as pump + controller. It is not possible to buy only a pump or only a controller.
3. One controller per pump, you cannot use one controller for multiple pumps.
4. The controller can be run with up to 18VDC. As voltage increase, so does pump speed and output. 
5. When run at 18 volts, this pump puts out 26% more flow than it does at 13.5 volts.


Selecting a fuel pump is based entirely on two factors: Fuel Type and power goal. Make sure the pump is compatible with your fuel type and that it flows enough to meet your horsepower goal (plus 20% or so safety factor). The table below can be used an approximate guide for selecting a fuel pump based on the power output of the engine. For multiple fuel pumps, just multiply the horsepower number by the number of pumps. The actual horsepower values achieved can vary greatly between different types of engines, so use this guide as a general approximation. Rotary engines should not use this table.

This chart shows flow rate vs. pressure for these popular pumps:

If noise is something that you are worried about, this chart compares pump noise. Each reading was taken under identical circumstances back-to-back.