Endurance racing involves teams of drivers competing in a single vehicle, taking turns driving laps on dedicated racing circuits. A popular form of motorsport, major events are the 24hr du Mans, the Nurburgring 24hr, and the 24hr at Daytona.
Endurance racing has also grown in popularity at an amateur level in recent years within North America, with organizations such as the World Racing League, Lucky Dog Racing League, Champ (formerly Chump) Car, and 24 Hours of Lemons offering events at popular racing circuits and attracting large fields of competitors. These organizations commonly require a valid driver’s license as qualification to enter an event. Professional organizations such as the FIA require racing licenses and medical certificates for the drivers.
Vehicle classing depends on the rule set of the organizer, however all forms of endurance racing feature vehicles of various classes and capabilities on the course at the same time. The addition of speed differentials adds an extra challenge for the drivers.
The winning team is determined by which vehicle completes the most laps within a predetermined period of time, the most common lengths being 24, 12, and 7 hours. There are also 36 hour races that require a significant commitment in both preparation, time, and finances.
The racing circuit is manned by turn workers that use common flags such as yellow, blue, red, and black to communicate with drivers. If drivers have committed a rules infraction, they are shown a black-flag by turn workers, and will have to report to the pits for a penalty stop as prescribed to the rule set.
Many amateur organizations enforce a strict no-contact policy on course, with drivers required to report to the pits if even the slightest contact is made between vehicles.
Drivers use in-car radio systems to communicate with their teams, commonly with a single point of contact during their ‘stint’ behind the wheel. The team can monitor the driver and vehicle condition, and make strategy recommendations based on what the driver is experiencing.
Organizers will mandate a maximum time that a driver is allowed to spend behind the wheel of the car during a given stint. At an amateur level, this is usually 2 hours. At professional levels, it is common from drivers to double-stint if their performance exceeds the competition and they have a good pace.
To change drivers, the vehicle is brought into the ‘hot’ pits which are tightly controlled by race stewards. The current driver will exit the vehicle so it can be refuelled, and the next driver can enter the vehicle. Small maintenance tasks such as adjusting tire pressures, checking fluid levels, and cleaning windshields can take place at this time. Any major repairs usually occur in the team garage or the assigned cold pit stall.
All cars are required to be equipped with full 6-point roll cages with side-intrusion protection, 6-point safety harnesses, fire suppression systems, and arm restraints or safety nets in case of roll-over.
All electrical devices including the engine must be disabled via an electrical kill switch that is mounted in a place that emergency workers can easily access. It is also common to require additional fire system controls for emergency workers, as well as a flashing indicator light that allows a car to be found in the night if it goes far off course. Front and rear tow hooks are required as vehicles are often towed off course.
Working brake lights are required for daytime events, and dusk to dawn racing requires functioning forward-illuminating lights.
The greatest safety risk in endurance racing is encountered while refuelling in the hot pits. Gasoline and hot vehicle components can lead to unwanted combustion, so strict rules are enforced during refuelling. It is common to limit the number of team members allowed near the car during refuelling operations, usually to the person refuelling the vehicle and the person holding the fire extinguisher. These team members have to be fully covered in fire-resistant clothing, and require a balaclava to be worn under a helmet in order to protect as much skin area as possible.
In order to encourage teams to not rush their refuelling procedures, at an amateur level it is common for minimum pit-stop times to be enforced. A common minimum time is 5 minutes.
Success in endurance racing relies heavily on preparation and the ability to keep the vehicle on course while ‘turning laps’. Time spent unnecessarily in the pits is costly to the team performance, so much effort is focused on planning and reliability in order to maximize the chance of victory. It is common for teams to require drivers to achieve a competitive lap time that still leaves a margin for error, unlike time attack racing which requires all-out driving for the lowest lap time possible.
Because drivers are placed in a high-stress environment for extended periods of time, certain care is taken to ensure driver endurance and physical well-being. It is common to run a driver cooling system, as well as ensuring that there is adequate ventilation within the vehicle. Due to the physical demands, drivers commonly cross-train in endurance sports such as cycling or running.
CircuitStorm Data Logging and Analysis Software for Android features a predictive lap timer and coach that allows drivers to maintain consistent, safe lap times during an event. Pit speeds are displayed when the driver is driving below race speed such as in the pits, where going over the allowed speed will carry a penalty.
By setting a pit stall GPS marker, a pit stop timer is displayed to indicate how much time is left to prepare the next driver and release the car. A driver list is configured and the current driver will be automatically rotated based on the order of the list. This can be overridden and a driver manually assigned if a change in driver order is made.