Auto safety questions: how nascar safety works

A discussion of NASCAR safety features from the car's construction to the race itself, including the cockpit, regulations, and track features.

In most states, high-speed driving is considered reckless because of safety hazards. Yet stock car races routinely run faster than one hundred miles per hour, and few injuries result from the most violent crashes. When the National Association for Stock Car Auto Racing (NASCAR) was founded in Daytona Beach, Florida, in 1948, it followed only basic safety conventions. As cars have become faster and more powerful, however, safety restrictions have increased accordingly. Today, NASCAR stock cars incorporate aerospace engineering principles to uphold strict safety standards, and safety regulations are followed from the car’s construction until it crosses the finish line.

NASCAR Safety: Car Construction


Stock cars are built to work with the laws of physics and protect the driver’s life during an accident. At high speeds, cars have up to twenty-five times as much energy as normal driving speeds, and that energy translates to between fifty and one hundred times the force of gravity during a crash. To reduce that energy, stock cars are constructed to absorb the impact while at the same time maintaining enough integrity to minimize flying debris.

A stock car’s tires often have different compositions on the left and right sides, with the left, or interior, tires being softer. This allows the car to lean more heavily on that tire during tight turns, reducing the chance of a skid. Some tires also use a safety shield, an inner liner designed to support the car if the outer tire is ripped away. All four tires are tethered to the car to help keep them attached during a crash.

To keep a car from becoming airborne when it spins, roof strips and flaps have been adapted from airplane technology. Roof strips are one-half inch aluminum strips that run lengthwise to keep a car from flipping, and roof flaps are panels near the rear of the roof that operate by aerodynamic pressure to keep the car grounded. When the car spins or turns backwards, the pressure forces those flaps to raise, disrupting the airflow around the car and creating more downward force to increase the tires’ traction. The spoiler, or metal blade, on the rear of the car operates the same way.

On certain race tracks, such as the Daytona International Speedway in Florida and the Talladega Superspeedway in Alabama, cars are required to use engine restrictor plates. These metal plates restrict the airflow and fuel concentration between the carburetor and the engine, forcing the cars to maintain slower speeds. These two tracks are the longest and fastest used by NASCAR, and such safety precautions are necessary for the drivers as well as the spectators. If unchecked, cars on these speedways could easily exceed two hundred miles per hour, and the walls separating the track from the stands could not withstand such impacts. As an additional precaution, many smaller tracks are using softer barrier walls that can absorb more of the impact and cushion the car in the hopes of lessening the severity of many crashes.

The fuel cell in a NASCAR vehicle is superbly reinforced and nearly leak-proof. It is composed of a flexible bladder surrounded by foam and encased in a metal box. This triple layer of protection minimizes fuel spills, potential fires, and explosions that could result from the twenty-two gallons of fuel carried by these race cars.

Other safety features on stock cars include hood pins to keep the hood closed and attached during crashes, as well as an anti-roll bar, or sway bar, beneath the car to increase stability on tight turns. Cars are also equipped with impact data recorders that record forces, change in speeds, and other instrumental information during an accident. That information can be used to improve safety features in all cars and prevent future accidents.

NASCAR Safety: Cockpit Features

While most of a stock car is designed to crush on impact to absorb the shock and energy of a crash, the inner portion of the car, where the driver sits, is reinforced and outfitted with multiple safety features. Because of this interior steel tubing – the roll cage – many drivers walk away from severe crashes unscathed.

The cockpit contains two kill switches the driver can use during an emergency. A master switch shuts down all the electrical components, and the ignition kill switch shuts down the car’s engine. If necessary, either of these switches can be used to help control or eliminate a fire. Additionally, a fire extinguisher is on hand as well as a switch to release fire suppression chemicals and foam into the cockpit. The driver’s suit and gloves are also flame resistant.

The driver’s seat is specially designed to provide extra support for the head, neck, shoulders, and chest. By spreading the area of contact as much as possible, pressure from a crash can be more evenly distributed across the body, decreasing the overall force. NASCAR also mandates the use of head-and-neck restraints to help prevent excessive jostling and potential injuries. Drivers are required to wear helmets, most of which provide full-face coverage with visors using plastics that are found in bullet-proof glass. The seat belts are stronger than those in ordinary cars, and include two shoulder belts, two waist belts, and a fifth strap between the driver’s legs.
To provide additional protection for the roll cage, the cars use sturdy metal plates called firewalls to separate the cockpit from the engine compartment in the front and the fuel cell in the rear. This helps maintain the integrity of the roll cage. The window net prevents the driver’s head or limbs from being exposed to debris. In an accident, the driver must be able to exit the car quickly, and most cars are equipped with clips that allow the windshield to be swiftly removed if necessary. NASCAR is also developing a roof exit system that could assist drivers if the car comes to rest on its side.

NASCAR Safety: Race Regulations

Like any sport, NASCAR follows strict standards designed to safeguard the participants. The first regulation is the use of the pace car – a car that leads the racers for three warm up laps at the beginning of the race. This warms up the engines and tires of the cars, which helps them reach their peak performance and run more safely. Throughout the race, a series of colored flags are used to communicate with all drivers about track conditions: a yellow flag means hold position and proceed cautiously in single file, a red flag is used to stop the race immediately, and a black flag signals a single car to stop immediately. The blue flag with a diagonal yellow stripe is the most common, and is shown to slower drivers to indicate that they are about to be passed by lead lap cars, to whom they must yield.

Every racing team uses a number of spotters, individuals who watch the entire race and communicate with their driver via radio to warn them of debris and help them pass other cars safely. Members of the pit crew service the car when it refuels, and penalties can be assessed against the team if they fail to perform their duties safely, such as failing to install five lug nuts on each wheel.

Even the track itself is designed for safety. Walls, fences, and steel gates are used to protect spectators. Drivers can be given penalties for unsafe driving, including speeding through the pits, such as being forced to return to the pits safely and come to a complete stop for a full second. While it may not seem like a long penalty, it can easily cost a driver his position in the race. When leaving the pits, drivers must stay below the blend line that connects pit road to the first turn, allowing them to merge safely back into the speeding traffic. This insures that they can accelerate appropriately without forcing other cars to swerve.

Today, NASCAR is not only the fastest moving sport in America, but it is also the fastest growing. From roof flaps to the roll cage to the yellow caution flag, NASCAR focuses on safety for both the participating teams and the spectators. These regulations lead not only to more exciting races with few injuries, but also to safer passenger cars as stock car standards are introduced to regular vehicles. Whether in the pits at Daytona or the driveways of America, NASCAR is working to make all driving a little safer.

Auto questions: how car engines work

Car engines, also known as internal combustion engines, are designed to do one thing well- turn a crankshaft.

Car engines have a lot in common with electric motors- they both perform one task very well. Both systems are designed to cause a shaft to spin. The force generated by that spinning shaft may be re-routed to perform other functions, but that is the only specific job of a motor or engine. The amazing engineering involved with a car's engine lies more in how that spinning force is achieved.

A car's engine is properly defined as an 'internal combustion engine'. This means that the motor burns its fuel source within its own housing. Other systems designed to turn a shaft (such as a mechanized pulley) may rely on outside fuel sources to run, but a modern car engine is completely self-contained. The combustion of a gasoline/air mixture creates all the energy a car's engine requires.

But how does an engine generate power? It starts with the fuel source. A very powerful chemical compound called gasoline is stored in a holding tank until needed. When a driver places a key into the ignition, an electrical system is activated. Of primary importance is the powerful electric battery stored securely near the engine. When a key is turned, power from this battery goes to a starter assembly. This is basically a strong electric motor with a large gear (bendix) located in front. The starter's gear meshes with a very large gear connected to the shaft assembly of the engine itself.

As the starter starts to spin the flywheel, a mixture of filtered air and atomized gas is sprayed into a series of cylinders located on the top of the engine housing. This gas mixture is ignited by ceramic spark generators (plugs) located at the top of each cylinder. A car may have 8 or more of these cylinders, so they obviously cannot be ignited at the same time. The idea is to stagger the explosions so that each cylinder pushed down on a valve and piston in a precise order. This is accomplished primarily by a distributor- a device that electronically controls the order of sparking. As the gas in each cylinder explodes, the 'floor' of the chamber is pushed down forcefully. This is actually the top of a piston which is connected to the engine's main shaft. Ideally, each piston pushes down on the shaft just ahead of the next one. The shaft itself is designed with protuberances that mechanically force the pistons back up. This action is much like a bicycle pedal being forced back to the top as the opposite pedal is pushed by the rider. The pistons do their work on the down strokes while the crankshaft forces them back up on the upstrokes. Waste fumes from the original explosion are forced out of the cylinder as the piston returns upwards, and the entire cycle is repeated.

The result of all these pistons bearing down is a spinning crankshaft. This main crankshaft has several gear assemblies attached to it, such as a belt drive that powers the car's electrical and coolant systems. Heat generated by the exploding gasoline and the friction of the pistons rubbing against the metal engine must be controlled. The water pump mechanically forces water and special engine coolant to circulate around the engine block. The ultra-hot water is then recycled through a radiator, which dissipates the heat by spreading it over a large surface area. Cooler water is then recirculated into the engine block.

Another gear assembly from the engine's main shaft meshes with another shaft designed to change the direction of the spin. This is called the transmission, and it is vital for the car's intended purpose of transportation. The connection from the engine to the transmission must be maintained nearly perfectly or else the gears will fall out of alignment and destroy the transmission. The transmission directs the power from the engine to two more sets of shafts called the transaxels. These geared shafts redirect the direction of the spin once more, which allows the tires to move forward and backwards with enough torque to overcome the inertia of a stationary car and create some momentum.

A car's engine could theoretically run forever as long as it had a fuel source and electrical power for ignition. But most engines eventually wear out because of friction and stress. Engine oil helps to keep the valves and pistons lubricated, but eventually leaks develop around critical seals and the engine becomes less efficient. Spark plugs can also become fouled with excess carbon generated by the gasoline, and transmission parts may become damaged over time. An internal combustion is an amazing feat of engineering because the entire system can move with the machinery it powers.