Testing the Radium Fuel Surge Tank

After countless CAD models, design revisions, rapid prototypes, a custom aluminum extrusion and working with our machinists, we have our first batch of Fuel Surge Tanks (FST). The FST is designed to augment a factory fuel system. It works by ensuring a constant and reliable supply of fuel to the engine under all conditions. Each fuel surge tank contains a high performance fuel pump that provides extra fueling capability.
Exploded view showing Fuel Surge Tank with internal fuel pump

Before releasing the system for sale, we thoroughly tested the device. A concern for the FST design was the potential heat that could transfer to the fuel from the internal fuel pump. Our testing was to see if the surge tank would act as a fuel heater.

The (raw aluminum) prototype, fully assembled and ready to test

Testing utilized two different fuel system configurations to evaluate and compare results. The first setup used the Radium FST with an internal Walbro 255lph pump. The second setup used an external Walbro 255lph pump without a surge tank. Both tests used white spirit as the working fluid. White spirit is a commonly used solvent found in fuel injector and fuel pump cleaning processes and has similar properties to gasoline. The minimal use of only 1.5 gallons of fluid would simulate a low fuel condition and make temperature changes more immediate.

Fuel Surge Tank plumbed for testing

We chose to operate our high pressure line during both tests at 4Bar (~58 psi) using a Radium Fuel Pressure Regulator. This pressure was selected to fully load the pump to create the worst case scenario where the pump is exerted to the maximum work load and heat levels peak.

High pressure line entering regulator (blue fitting), temperature probe plumbed into opposite side port

Ambient temperature was recorderd and was within 1 degree C during all tests. Fluid temperatures were monitored at the same locations in both setups and were measured using thermocouples in the reservoir(T1) and in the high pressure line(T2) via a port on the regulator.

Power was supplied to the pumps using a 12V battery with an attached variable rate charger. This allowed constant voltage with varying electrical loads. The tests ran at a steady 12.3V and temperatures were recorded every 5 minutes for 90 minutes.


The first test used the Radium Fuel Surge Tank setup (shown below). In this test, the high pressure line that normally feeds the fuel rail and injectors is sent directly to the fuel pressure regulator and returned to the FST.


Test Setup 1. Utilizing Radium Fuel Surge Tank (Blue)


The second test consisted of the same basic set-up. This time the reservoir's pump fed an external (in-line) Walbro 255lph pump (shown below) rather than the Radium FST. This eliminated any heating effects from the external surface of the pump.

Test Setup 2. Utilizing a Walbro external pump

The results were quite surprising.  We speculated that the FST internal fuel pump would transfer more heat to the fluid due to its submersion.  The results strongly proved otherwise...

The chart above shows the fluid temperatures (average of T1 and T2) over time. It is clear that having the pump internal to the Fuel Surge Tank (blue line) does not excessively heat the fuel. In fact, it appears that the FST might provide some extra cooling that does not occur with the external pump (red line).
The yellow line represents a single pump in the reservoir using the same fuel pressure regulator, which simulates the factory fuel system.The green line shows the ambient temperature.

These results show that over 90 minutes the fluid temperature increases 20-30 degrees celcius. This will not have any noticeable effect on engine performance. Fuel density only decreases by roughly 2%. When considering the air/fuel ratio, there is typically 12 times more air than fuel in the cylinder which would make any effects even more inconsequential.

Based on the test results, we are confident about releasing our Fuel Surge Tanks for sale. We will be releasing FST kits for specific vehicles and applications. We will also have FST that utilize other popular fuel pumps including the Bosch 040 and Bosch 044.

We will be publishing a more detailed informative blog entry on the FST very soon.
More Info:

Club Lotus NW at Lotus of Portland

2011 Elise

Lotus of Portland was kind enough to host a Club Lotus NW meeting for local members in mid November. Not only did they donate their time and facility for club business, they also supplied the group with beer and pizza. Steve Wintermantel is the guy in charge and was a gracious host. We also got a chance to get up close and personal with the newly restyled 2011 Elise and the Evora.

2011 Elise, Rear

Evora Interior

Steve discussing the finer points of Lotus ownership

Exige S

Thank you to Steve and Lotus of Portland for their support of local enthusiests.

New Product Intro: Fuel Pressure Regulator

We are excited to have our first batch of our Radium Engineering external Fuel Pressure Regulators (FPR). An external FPR is a necessity when upgrading a fuel system for forced induction or other modifications. Among other benefits, It enables a higher fuel pressure to be utilized, which can be beneficial for flowing more fuel through the fuel injectors.
We designed this product around a Bosch regulator unit that is OEM on many modern vehicles. This regulator unit has been proven reliable. Instead of dealing with finicky springs and leak-prone aftermarket diaphragms, we chose to keep it simple, reliable, and affordable. The Bosch regulator unit is housed in our own 6061 billet aluminum body. We designed the body to be compact and feature-packed.

The housing has two regulated ports that are threaded 9/16-18 for -6AN fittings along with one 1/8NPT port for a pressure gauge or pressure transducer (for data logging). The return port on the bottom of the housing features a -6AN male flare integrated into the body, eliminating the cost of an additional fitting.

We will be offering the FPR's in 3 different static pressures: 3, 3.5, and 5 Bar. Each one is 1:1 vacuum referenced.  We will even be offering an adjustable version. The regulator unit can be removed from the housing by removing the retaining ring that holds it in. This allows different units to swapped in, and can be handy for servicing or cleaning the FPR. Replacement regulator units are available from most major auto parts retailers, should the need arise.
These regulators will come anodized black or Radium Green and include a powder coated aluminum mounting bracket and hardware. For more information and pricing see our product page here: Radium FPR

Please Note:
Changing fuel pressure should only be done as part of a carefully thought-out plan of modifications. If fuel pressure is changed from what the OEM engine control computer is calibrated for, it can cause serious problems.

Video:Testing at Thunderhill Raceway

Back in September we had the pleasure to join the Golden Gate Lotus Club on the track at Thunderhill Raceway Park in northern California. It was a blistering hot day and it really put our products to the test.  For a full write up on the day, see our earlier blog entry: Click Here.

We were running our prototype State II turbocharger kit, which consists of the stock 2ZZ-GE engine, and our bolt-on components.  We also run the stock 6-speed transmission and stock muffler.

Below is a video comprised of footage we compiled throughout the day. As you will notice, we were running the track in reverse which presented new challenges to everyone. The GG Lotus Club did an excellent job managing the event and keeping the drivers in check.  It was a great learning experience and a perfect venue for pushing the limits of our Stage II turbocharger system. Enjoy:

Zero to 60 Testing

A vehicles zero to 60 time is considered a very basic and necessary performance statistic. It allows a direct comparison of the acceleration to any other vehicle.  We recently took some time to find out what our prototype turbocharged Elise could do. The car is making approximately 305Hp at the wheels using the stock 2ZZ-GE engine and our Stage II Sport turbocharger kit. We are also running the stock tansmission and clutch. Tires were Kumho V710's. Measurement was done with a Vbox PerformanceBox.  After many attempts, we were able to pull off a run of 3.8 seconds. Click the video below to see the action.

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