Project Lexus SC300 Road Racer: Part 1 – Intro and Fuel Cell

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Here’s one example of the fun stories I have about this car. Zip ties holding the fuel pump onto the bracket? Sure, why not. #SEEMSLEGIT
Getting boxes of car parts delivered always makes it feel like a fun holiday. But I wonder what could be inside these?
Radium Engineering and Fuel Safe have partnered to produce Radium fuel cells.

They combine Radium’s Fuel Cell Surge Tank (FCST) with your choice of Fuel Safe cells. This particular example is cell 00000001 – the first one EVER! Well, Fuel Safe has been building cells for more than 30 years, so that’s a bit of an overstatement. But it is the first cell that Radium and Fuel Safe collaborated on, and MotoIQ got to be the first to use one. What’s so great about a fuel cell? What’s the surge tank for? Time for a TECH BREAK!

A factory fuel tank is designed with a very wide range of characteristics in mind. Engineers have to look at factors like range and capacity, crashworthiness, keeping the car from being stinky, emissions, and many other things. From a safety perspective, the fuel tank is made of pretty tough coated metal. That also makes the tank heavy. It’s designed to survive a collision, and is located in a place that helps to minimize the odds of it being severely damaged during one.

A fuel cell is made of a lightweight outer shell (20 gauge powder coated steel, in the case of the Pro Cell) and has a bladder inside. This bladder is what holds the fuel, and, on the Pro Cell, meets FIA FT3 certification. The FIA certification has to deal with puncture, tear, deceleration and other resistances. A street fuel tank is designed primarily for highway-speed incidents. Racing incidents can happen at much much higher speeds and, therefore, involve much much higher forces.

As you can see from the earlier picture, the fuel tank is located up and in between the shock towers. This keeps it safe, but isn’t optimal. The specific gravity of unleaded gasoline is generally around .755 kg/L. A 20.6 gallon SC300 fuel tank holds 77.98 liters. 77.98 x 0.755 = 58.8749 kg, or approximately 123lb. That’s a lot of weight to have well above the center of gravity of the vehicle. Heck, it raises the center of gravity of the vehicle. And that doesn’t even include the weight of the tank itself!

The factory baffling in a fuel tank is good, but not great. I’ve experienced starvation issues with Damnit during cornering even with several gallons of fuel in the tank. Fuel starvation, especially on a turbo car, is not a good thing. A proper racing fuel cell is full of fuel-compatible foam baffling that helps prevent sloshing and helps to keep fuel near the pick-up.

This is also where the surge tank comes in.

This is the underside of the Radium Engineering FCST.

It combines a lift pump and a primary pump in the tank. The lift pump lifts fuel out of the cell and pushes it into the 2.2-liter surge tank. The primary pump then pushes the fuel from the surge tank out to the engine. Whether you are pulling high Gs from hard drag launches or high-grip cornering, the surge tank helps to ensure that fuel flow to the motor remains constant – no more starvation!

 

The “Fuel Cell” part is the fact that this setup is integrated into a top plate that fits standard racing fuel cells, like Fuel Safe’s PC122, the 22-gallon tank we are using. The top side of the FCST has -AN ports for hoses and our FCST came with the optional fuel filler neck and a rollover/vent tube.

6 comments

  1. i have a 1992 sc300 gte engine and i was looking to do the same i have dual exhaust on my will i have enough room to run that fuel cell but nice work

    1. You will definitely need to modify your exhaust to fit a fuel cell if you go with one as large as this. Ideally you would figure out your fuel consumption rate in G or L per minute, and then figure out your target run-time, and then size the cell accordingly. I probably could have used a _much smaller_ cell.

  2. i have a 97 SC300 just sitting on the side of my house and just need to spend some time with it
    this is my 3rd one in amazing condition

  3. Hey Erik I’ve kept close tabs on this blog and now I have an SC400 that’s ready for a fuel upgrade! I’d like to run the same setup you have, but I can’t make out what the dimensions of your fuel cell are. Is it the 25.75″ x 25.75″ x 8.5″?

    1. Looking back, we have a Fuel Safe PC122C cell which Fuel Safe lists as 25.5 x 17.125 x 13.75 — However:

      Radium discontinued its partnership with Fuel Safe some years ago and is now making its own cells from the ground up. They carry FIA and SFI certifications.
      https://www.radiumauto.com/Fuel-Cells-RA-Series-P1822.aspx

      If I had to do it again, I would not go with such a large cell. But things have changed. The car is a full-on race car that I trailer to the track, so I have no problem with filling it every session. 22Gal would be good for a “drive to the track” car but is quite ridiculously large for other circumstances.

      Also, check out the PRI coverage from 2023 — Radium has a really trick new design for the FCST that makes changing pumps a breeze.

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