Fuel Cells

There are two kinds of safety equipment in racing today. One type directly involves the driver and his or her immediate area. Items such as lap belts, harnesses, window nets, seat and leg wings, rollbars, and fire-suppression systems are all within reach, hopefully forming a protective cocoon around the driver.

The other type of product is still on the car but away from the driver and yet contributes greatly to safety. Two of those remote items are staples nowadays, and teams would never consider racing without them. One is the inner liner for tires. The other has made its way to virtually every form of racing and even the street: the fuel cell. While simple in theory, it is a multifaceted device that does quite a bit more than you think.

To understand the fuel cell completely, go back to 1964. NASCAR was at a crossroads.

With more larger tracks added to the schedule, savvy builders had already begun to let the cars have their lead, and top-end speeds rose. But as the cars got faster and raced harder, crashes began to occur more often.

That’s when bad things started to happen. Tires would periodically blow out; that much wasn’t new, as the inner liner wasn’t invented yet. The most common tire was the right front, so the cars would go almost straight to the outside wall. If a driver with a tire blowing was under another car or two, then they too would be part of the wreck.

Multiple car wrecks or not, the front and back ends were the natural crush zones of bending, twisting, and tearing metal. While there was only limited fuel up front in the engine compartment, a wreck involving the rear of the car was considerably more dangerous. With impact to the rear, gas tanks would split, and an already scary wreck would be even more so when 22 gallons of racing fuel was ignited. From these wrecks of blown tires and fires, drivers died. Among them, one of the giants of the sport, Glen “Fireball” Roberts.

While tire engineers worked on the development of the inner liner, something was clearly needed to reduce the chances of fire when the back end of the cars was crushed. At the time, factory gas tanks with added steel baffles were used. The baffles were installed to keep the fuel within the range of the fuel pickup, or the engine would starve. Racers had already learned not to try to move the gas to the pickup, but locate the pickup where the fuel would be.

On a car that is constantly turning left while going forward, the logical place was at the rear of the tank and all the way to the right. It was even more pronounced on the bigger, banked tracks where centrifugal forces were greater. When those simple steel tanks were torn open in a wreck, nothing could keep the fuel inside the tank. It was like breaking a piggy bank.

Crashes in those days were only slightly different from today. More tracks had metal guardrails instead of concrete walls—purely an appearance difference. But similar to today, they involved impacts of car metal with guardrail metal and pavement materials such as blacktop and a few concrete walls. It was the perfect opportunity to mix sparks and fuel.

Something was needed to contain the fuel despite any crash that would rupture the tank. The basic properties of metal suggested this could not be done, so maybe the answer was not in metal. Some sort of rubber or fabric bladder inside that metal tank might do the trick. But no material anywhere could guarantee holding its load under crash conditions. That much was known from airplanes.

The fuel cell started its evolution with a neoprene bladder inside a steel gas tank, but there was more to it than just that. Neoprene was not designed to be a strong material as much as to contain a liquid. It could still be torn easily, and the bladder needed more strength to resist tearing under impact. To reduce the chance of jagged metal from the car (in a crash) cutting the bladder, the neoprene was reinforced with nylon, thereby giving strength to the bladder. The nylon web of the cell was actually coated with this material for maximum strength and protection.

The advantages of the fabric bladder were clearly superior to metal. When metal is torn or ripped apart, it has virtually no resilience, and once torn, it stays that way. Neoprene, on the other hand, is more flexible and when stretched, mostly will return to its original shape. That means when a piece of metal punctures the fabric and is removed, the opening created will close up to some degree. Less fuel will spill out and will be less likely to surround a car and driver with a large fire.

Another improvement was the addition of sponges inside the bladder. They have two functions: to keep the fuel from sloshing around during its normal operation in the tank, and to eliminate steel baffles (no steel exists inside the bladder). The sponges also keep the fuel near the pickup, still located on the right rear of the bladder. An additional benefit is the ability to retain as much fuel as possible, depending on position, during and after an impact if the bladder was cut or torn. This also greatly reduced the amount of fuel spilled if the cell was punctured.

So, between the cell retaining the fuel in a rupture and the sponges holding it, less gas is released in wrecks, which results in fewer fires. It gives a mobile driver more time to get out and a hurt driver more time for the rescue crew to assist him and manage the fire.

In addition to the fuel cell’s new materials, a new mechanical system was created, which allows the fuel to enter the cell but not exit. Basically, the fuel goes in the top of the cell via 21/8-inch tubing and utilizes a separate 1-inch breather line to allow air to escape as the fuel fills the space of the tank.

On pit stops, we see a crewmember holding the catch can to collect overflow fuel. The overflow hose leads out the left rear of the car, usually where the taillight would be, and lets air out. Those two hoses are the ones we still see when looking in the trunk area of today’s race car.

But what happens when the left-rear corner of the car and the hoses are damaged, and the fuel cell is upside down? After fuel kept running out of a gas tank when a car was overturned, another invention was needed—something to stop that fuel from coming out of both openings. What we don’t see are the ball check valves inside the cell and under the inlet framework on the top of the tank. It’s a simple device that works on the same principle of gravity as fueling a car. The underside of the inlet housing holds two heavy ball bearings inside separate cages. The larger one is for the inlet, as that hose is the bigger of the two. When the cell is in the normal position, the balls sit in the bottom of their respective cages. If the assembly is turned upside down, the balls move up the walls of the cage and fill the inlet and breather holes, thereby stopping any fuel from escaping.

To further ensure the cell’s best chances of survival, significant reinforcing is done around the tank in the frame of the car. The cells are encased in 20-gauge steel. The sides and top are enclosed in 1x1-inch steel tubing, with a minimum of two tubes each in both directions. On the bottom of the car, they are supported by three additional sections of tubing on the floor pan between the two framerails.

A fuel cell can be compromised in a wreck and still do its job. Every now and then, we’ll see an accident where the fuel cell is broken upon impact and only a small fire starts. That’s because the cell contains the remainder of the fuel inside, and only the spilled fuel has been ignited. By holding the fuel with sponges, the fire is somewhat controlled, making it easier for the driver to exit and fire crews to keep the fire from an injured driver.

But make no mistake, for all the lives the fuel cell has saved over the years, it cannot be deemed “bulletproof.” Fire is comprised of three elements: heat, fuel, and air. Racing takes place with plenty of air, so fire needs only fuel and one simple spark to start. Metal cars collide with each other and walls, so there is no shortage of sparks. We’ve all seen cars seemingly burst upon impact from the rear or in the wall; until a truly bulletproof bladder is invented, the chance of explosion will always exist. In the meantime, the fuel cell will stand its guard and continue to reduce the possibility of fire reaching the driver.