Playing The Fueled

Can’t decide whether to run a fuel cell or get your stock tank sumped? We didn’t have to decide; we had Fuel Safe build a fully functional fuel cell with the external dimensions of LeMans’ stock gas tank, so it fits in the factory location. Running a typical fuel cell means compromising valuable trunk space, and having to hack an enormous hole in the trunk floor to clear the sump. There’s absolutely no hacking necessary to install this tank; it even uses the factory floorpan mounting points to attach its stock-type straps. The shiny aluminum housing hides a bunch of trickery within. If you choose to have the can powdercoated black, it’s almost indistinguishable from stock!

Very few fuel pumps are capable of supplying 50-plus psi continuously at the volumes required for a high-horsepower electronically injected engine. Even fewer fuel filters are capable of providing 10-micron filtration without creating a huge pressure drop across the filter element. Holley engineer Doug Flynn gave us the nod to use the company’s PN 12-920 inline fuel pump. It’s rated for continuous duty, capable of pumping 255 liters/hour, and the insulating cover keeps it pretty quiet. Finding suitable filters was an exercise in frustration, but the heroes at Kinsler Fuel Injection ended our quest. The pump and filters were mounted with cushion clamps off the passenger-side rear framerail.

The knowledge pool of the Kinsler staff is astounding. Kinsler’s Earl Miller recommended installing the company’s 25-micron filter before the fuel pump, followed by a finer-media 10-micron filter on the pump’s pressurized outlet. Kinsler calls the larger, 25-micron filter its “Monster Mesh Pump Protector” as it contains a full 60 square inches of stainless steel screen, tucked into a relatively small (6.75-inch long) housing. It creates very little pressure drop so the pump won’t cavitate as it pulls fuel across the filter element. The 10-micron “Injector Protector” filter contains 33 square inches of aircraft-grade pleated paper, fine enough to keep junk out of the injectors, but free-flowing enough to keep from loading up the fuel pump. Kinsler carefully chooses filter elements with the largest possible surface area so they can hold more dirt without becoming restrictive. Do yourself a favor and give the folks at Kinsler a call before you contemplate taking any shortcuts in your EFI fuel system.

Fuel Safe offers countless fuel-fill options, including flush fender-mount doors, but we wanted to retain the factory filler location hidden behind the license plate. We installed the filler neck after bolting the tank in place, and boy, did that make for an easy installation. Ever notice that GM A-body cars like dumping gas out of the vented filler cap under heavy acceleration? Fuel Safe’s O-ringed cap solves that. The tank is vented instead through the top-mounted AN-8 fitting. We later exchanged this vent for a 90-degree fitting, which allowed more clearance against the trunk floor. Braided AN-8 hose was run up and behind the bumper and terminated with a paper breather filter. Check valves in the filler and vent fittings keep gas from pouring out in the event of a rollover.

Sumping a stock gas tank means you’ll have a lot of bulky plumbing and hardware hanging down below the bumper. Most car-guys don’t mind the “serious” look of a big ol’ fuel pump back there, but Fuel Safe rigged up a trick alternative. The pickup and return fittings were installed in the stock locations, and fuel is siphoned into the pump from an internal surge tank with check-ball baffles so there’s no chance of sucking air under hard acceleration or high-g turning. The resulting low profile of the tank allows us to mount the fuel pump at frame-level, still get a strong fuel feed siphon, and easily route short sections of Earl’s braided hose to the Classic Tube stainless hardlines. The top-mounted plate holds a capillary-style fuel sender that’s compatible with our factory 0-90-ohm gas gauge. The two adjusting “pots” (arrows) are used to calibrate the sender to the gauge, but ours was pretty close out-of-the-box.

Fuel Safe designed our tank so it fills at the stock location, but most of its cells use a top-mounted fill plate. This plate is designed to connect to one of Fuel Safe’s cool fender-mount fillers with its durable clear filler hose. The vent fitting is cut away to show the metal check-ball that won’t let fuel spill out during a rollover.

There’s a whole lot of trick equipment inside Fuel Safe’s showy protective metal can. The most important component is the flexible internal bladder that lines the inside of the can. The Pro Cell bladder in our tank is made from double-coated nylon fabric, which is ultra-durable and flexible. There’s full foam baffling inside to displace oxygen, eliminating the potential for explosion. Pro Cell bladders have a 10-year warranty too—probably the only part of your race car that’s guaranteed to last that long. The compartment attached to the tank floor is a surge tank, complete with one-way check valves to retain fuel in the chamber.

What’s a surge tank, and why did we need one? A picture says a thousand words. A surge tank is a small chamber installed in a fuel cell that’s fitted with one-way check valves. These valves allow fuel to enter, but block it from flowing back out. Fuel that moves around the cell gets trapped inside the surge tank. The fuel feed to the pump is piped from the surge tank (arrow), which means there’s almost no chance of the fuel pickup sucking air, frying the pump, and starving the engine. Excess fuel dumps back into the surge tank after it circulates through the fuel system. Fuel Safe also sells these surge tanks separately so you can upgrade your own fuel cell or gas tank.

The first mistake we made when we planned our '65 LeMans fuelie conversion was mapping out the fuel system from a carb-centric perspective. The fact is, hardly anything from our carbureted fuel system could supply the injected 455 with the high-pressure, finely filtered fuel it needed. As carburetor-speaking tourists in a foreign EFI-versed land, we faced some challenges designing a fuel system and learned how few companies even offer the components we needed. Eventually, we pieced together products from no less than five companies—Fuel Safe Racing Cells, Holley, Kinsler Fuel Injection, Classic Tube, and Earl's—to complete a top-notch fuel delivery system. All of these guys are specialists, so they knew exactly what we needed and told us how to put it all together.

In previous stories we've laid out a few different options for EFI fuel systems including using a sumped stock tank with an external fuel pump, and modifying a stock tank to house a quiet, well-cooled in-tank pump. Here we'll show you yet another way to build a fuel system. It's not the cheapest plan of attack, but we think it's the most durable and versatile of the systems we've shown so far. We put forth the extra cash and effort on our Poncho so we wouldn’t have to redo it in the foreseeable future.

Click here for part 1--Inject The Unexpected

Click here for part 3--Fast EFI Tuning Basics