Fuel Cells & Fire Suppression
Fuel cells are a safety feature for race cars designed to minimize the risk of fire due to a ruptured fuel container. Sanctioning bodies often require and/or allow the use of fuel cells depending on the class and type of racing.
Fuel cell size is the first consideration when selecting a cell. Most sanctioning bodies limit the maximum size of the fuel cell. Endurance cars use the biggest cell possible to minimize refueling stops and maximize fuel range. Cars that compete in sprint type races will use the smallest cell possible to minimize weight, but carry enough fuel to finish a race.
Once the correct size cell is selected, positioning the cell in the car is the next critical step. Gasoline weighs approximately six pounds per gallon. A small cell holds five gallons of fuel while a larger cell could hold up to thirty gallons of fuel. Consequently positioning of the fuel cell in the vehicle will have a huge impact on the overall weight distribution of the chassis. Sanctioning bodies often dictate the positioning of the cell in the chassis. Many organizations require the cell to be installed in or near the stock location of the OEM fuel container. The fuel cell mounting frame needs to be custom built and is often integrated within the roll cage. This makes for a solid mounting system and allows the roll cage to protect the fuel cell.
Filler options should be carefully considered when selecting a fuel cell. Sanctioning bodies often require a dry-break system for safety. The dry-break makes for a rapid fueling rate during a pit stop. These types of fillers require a large fuel cell vent to expedite out going air when fueling. A discriminating valve is often used on most fuel cells to minimize fuel related fumes inside the car and prevent fuel spillage in the event of a rollover.
An important part of a fuel cell is the fuel pickup system. The pickup system should be designed to maintain constant fuel delivery during acceleration, cornering, and braking even during low fuel levels. It is important in endurance racing to extract the maximum amount of fuel from the cell to increase fuel range. Internal and external surge tanks are often used in conjunction with fuel cells to prevent fuel starvation. Many styles of surge tanks are available for various applications.
All features of the fuel system should be considered when selecting a fuel cell. The correct number and size of the plumbing connections should be installed at the fuel cell bulk head. Fuel pumps can be installed in a variety of ways with a fuel cell (internally and externally). Some elaborate cells use both internal and external pumps. High pressure and low-pressure application can also be used in most cells. A secondary pump is often installed as a backup system. A fuel gauge sending unit can be installed and often calibrated to the OEM fuel level gauge.
Most sanctioning bodies require a firewall/fire barrier between the fuel cell and the driver’s compartment. These are usually fabricated from steel or aluminum that covers or separates the fuel cell from the cockpit. These can be very time consuming and should be considered when estimating fuel cell installation costs. Piper Motorsport has much experience fabricating custom fuel cell mounting frames and covers in a variety of race cars.
A fire suppression system is one of the most important safety features in a vehicle. The primary purpose is to protect the driver and passenger from a vehicle fire. A secondary function is to protect the vehicle. Fire suppression systems are cheap insurance for you and your investment.
These systems come in a variety of styles and sizes. Sanctioning bodies require different systems for different types of racing. Consult your rulebook carefully before selecting a system.
There are two basic styles of fire suppression. The first and most basic is the hand-held fire extinguisher. These are used mostly for street-cars and competition classes that do not require an in-car fire system. Handheld extinguishers are often carried in addition to in-car systems for several reasons. A small fire (from a oil leak or brake rotor, etc.) can be extinguished without discharging suppression throughout the car. This also saves the expense of re-filling the entire in-car system bottle. Another reason is portability. This would apply to putting a fire out somewhere other than your racecar (i.e., pits, garage, competitors car, trailer, etc.). The second and more complex style of fire suppression devices is the in-car system. An in-car system has a large fixed mounted single bottle with multiple strategically positioned discharge nozzles. The nozzles are generally placed in key areas such as the engine bay, driver’s compartment, and fuel cell. The number of nozzles varies from system to system. The pressurized bottle is discharged through a mechanical or electrical device. The discharge control is often remotely positioned near the driver allowing the bottle to be mounted elsewhere in the car (bottles can be mounted to favor overall chassis weight distribution). A custom in-car bottle mounting bracket and nozzle tabs are usually required for proper installation.
It is critical that fire systems are installed correctly. This is one system on a vehicle that is not usually tested until it is needed.