restrictor plate

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Artist rendering of a NASCAR restrictor plate
A Restrictor plate or air restrictor is a device installed at the intake of an engine to limit its power. This kind of system is occasionally used in road vehicles (e.g., motorcycles) for insurance purposes, but mainly in automobile racing, to limit top speed and thus increase safety, to provide equal level of competition, and to lower costs.

Racing series

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Vitantonio Liuzzi driving a restricted STR1 at the 2006 Canadian Grand Prix.
A few top classes like Formula One limit only the displacement and air intake mouth dimension. However, in 2006 air restrictors (as well as rev limiters) were used by Scuderia Toro Rosso to facilitate the transition to a new engine formula.

Many other racing series use additional air restrictors (or limit boost pressure in turbo engines).

Rallying

After Group B cars were outlawed from rallying because they were too powerful (rumored to have reached 600 HP), too fast and too dangerous, the FISA decided that rally cars should not have more than 300 HP. For a while no special restrictions were needed for that (e.g. the Group A Lancia Delta HF 4WD had about 250 HP in 1987). But with development in the 1990s, Group A cars were rumored to have reached 400 HP or more. So the FIA mandated restrictors for supercharged and turbocharged engines in all categories (World Rally Car, Group A and Group N).

This means that the rally version of a car like the Mitsubishi Lancer Evolution can have less power than the street version (the "280" HP Evo VII was believed to have more than 300 HP, and in some markets there were FQ-320, FQ-340, FQ-360, FQ-400 versions, with the number representing the total horsepower).

It also means that the torque and power curves of the engine are unusual. The engine produces peak torque and almost maximum power at a relatively low RPM, and from there to the rev limiter the torque drops and the power does not increase much.

In 1995 Team Toyota Europe used an illegal device to bypass the restrictor (allowing an estimated extra 50 HP). Due to this the team lost their results in the 1995 season and was banned from rallying until the end of 1996.

NASCAR

NASCAR's NEXTEL Cup and Busch Series currently uses restrictor plates at Daytona International Speedway and Talladega Superspeedway. NASCAR routinely states that the NEXTEL Cup restrictor plate reduces engine power from approximately 750 hp to approximately 430 hp.

The device limits the power output of the motor, hence slowing both the acceleration and the overall top speed obtainable on the tracks where the cars are so equipped. An undesired effect, however, is that all drivers tend to form very large "packs" of cars that run closely (there may only be one second separating the entire field at times) together for the majority of the race. These large packs reduce air resistance which allows the cars to run faster and makes drafting easier. These restrictions are supposedly in the interest of driver and fan safety, although many members of both of these groups feel that the closeness of cars and their inability to achieve separation may actually make the racing at these tracks more dangerous, as there are often massive and frightening multi-car pileups during races. Such a crash is dubbed "The Big One" by drivers and fans. At Daytona and Talladega, most races are marred by at least one occurrence of such a crash as cars rarely become separated. Talladega is considered the more likely track for these instances to occur as the track is wide enough to have three to four distinct lines of racing, compounding the chances of a mistake by a driver.

Reason for restrictor plates

There have been three reasons that NASCAR used restrictor plates in its history.

The first use came in 1971 as part of NASCAR's plans to reduce the size of engines from 427 cubic inches (7.0 L) to 358 cubic inches (5.8 L). In order to allow teams with smaller budgets to race the larger engines, NASCAR made mandatory the use of a restrictor plate to be placed on larger engines to equalize performance with smaller engines. The transition ended in 1974, when NASCAR banned the larger engines, and went to the 358 cubic inch engine (a compression limit would be implemented in 1996). This was a transitional process and, as not every car used restrictor plates, this is not what most fans call "restrictor plate racing."

The second use came following the terrifying crash of Bobby Allison at the 1987 Winston 500 at Talladega Superspeedway. Allison's Buick LeSabre blew a tire going into the tri-oval and flew tail-first into catch fencing early in the event, injuring spectators (although not actually entering into the grandstands). After a summer where the two subsequent superspeedway races were run with aids to prevent cars from flying, and smaller carburetors (390 cubic feet per minute instead of 750 cubic feet per minute) proved to be inadequate to sufficiently slow the cars, NASCAR imposed restrictor plates again, this time at the two fastest circuits, both superspeedways: Daytona for all NASCAR-sanctioned races and Talladega for Cup races. The Automobile Racing Club of America also enforced restrictor plates at their events at the two tracks. In 1992, when the Busch Series began racing at Talladega, the plates were implemented.

In some tracks, NASCAR's concerns with speeds because of power-to-weight ratios result in restrictor plates at other tracks. The Goody's Dash Series (known now as the ISCARS series with its new ownership) used restrictor plates at Bristol during at least the last years of the series' existence when the cars were using six-cylinder engines (compared to the traditional four cylinder engines), in addition to their Daytona races.

However, restrictor plates are not used for Craftsman Truck Series trucks. Rather, air intake, aerodynamic, and, eventually, a tapered carburetor spacer were implemented for those races. Combined with the aerodynamic disadvantage of the trucks, this allows NASCAR to avoid the use of such equipment for the trucks.

The third use came in 2000. Following fatal crashes of Adam Petty and Kenny Irwin, Jr. at the New Hampshire International Speedway during the May Busch Series and July Cup Series races, NASCAR adopted Modified rules featuring a one-inch (2.54 cm) restrictor plate to slow the cars headed towards the tight turns as part of a series of reforms to alleviate stuck throttle problems which were alleged to have caused both fatal crashes. For the Cup race, it was used just once at the 2000 Dura-Lube/Kmart 300, allowing Jeff Burton to dominate by leading all 300 laps in the ensuing race. Due to the lack of passing and the addition of an automatic kill switch in the case of a stuck throttle, the use of restrictor plates, intended as an emergency measure pending a more permanent replacement in any event, was discontinued at New Hampshire for the following race for Cup only. However, the Modifieds still use a restrictor plate, especially with the numerous deaths of star drivers in the history of the Whelen Modified Tour, yet no driver has died in the WMT at NHIS.

Rusty Wallace tested a car at Talladega Superspeedway without a restrictor plate in 2004, reaching a top speed of 228 MPH in the backstretch and a one-lap average of 221 MPH. [1] Wallace subsequently described the experience as "out of control".

References

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Automobile racing (also known as auto racing, motor racing, or car racing) is a sport involving racing automobiles. Auto racing began in 1895,[1] and is now one of the world's most popular sports.
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Category Single seaters
Country or region International
Inaugural season 1950[1]
Drivers 22
Teams 11
Engine suppliers 6
Drivers' champion Fernando Alonso
Official website formula1.
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Scuderia Toro Rosso (Italian for Red Bull Stable) is a Formula One racing team owned in a 50/50 partnership between the drinks company Red Bull and former F1 driver Gerhard Berger, and which made its racing debut in the 2006 Formula One season.
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Formula Three, also called Formula 3 or F3, is a class of open-wheel formula racing. The various championships held in Europe, Australia, South America, and Asia form an important step for many prospective Formula One drivers.
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Category Touring cars
Country or region Germany
Inaugural season
Drivers 20 (2006)
Teams 7 (2006)
Constructors 2
Engine suppliers 2
Drivers' champion Bernd Schneider
Teams' champion H.W.A.
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Sports car racing is a form of circuit auto racing with automobiles that have two seats and enclosed wheels. They may be purpose-built or related to road-going sports cars.
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The Automobile Club de l'Ouest (Automobile Club of the West - referring to the western region of France), sometimes abbreviated to ACO, is the largest automotive group in France.
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Alms or almsgiving exists in a number of religions. In general, it involves giving materially to another as an act of religious virtue. In Abrahamic religions, alms are given as charity to benefit the poor.
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The Group B referred to a set of regulations for competition vehicles in sportscar racing and rally racing regulated by the FIA. Group B was introduced by the FIA in 1982 as replacement for both Group 4 (modified grand touring) and Group 5 (touring prototypes) cars.
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The "Fédération Internationale du Sport Automobile" (FISA) was the governing body for motor racing events.

In 1922, the FIA delegated the organisation of automobile racing to the CSI (Commission Sportive Internationale
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Horsepower (hp) is the name of several non-metric units of power. The most occurring conversion of horsepower to watt goes 1 horsepower = 745.7 watts. In scientific discourse, the term "horsepower" is seen as inferior and is rarely used because of its various definitions and
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In relation to motorsport governed by the FIA, Group A referred to a set of regulations providing production-derived vehicles for outright competition. In contrast to the short-lived Group B and the Group C, the Group A referred to production-derived vehicles limited in terms of
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In relation to motorsport governed by the FIA, Group A referred to a set of regulations providing production-derived vehicles for outright competition. In contrast to the short-lived Group B and the Group C, the Group A referred to production-derived vehicles limited in terms of
..... Click the link for more information.
World Rally Car is a term used to describe the racing automobiles built to the specification set by the FIA and used to compete in the outright class of the World Rally Championship (WRC).
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In relation to motorsport governed by the FIA, Group A referred to a set of regulations providing production-derived vehicles for outright competition. In contrast to the short-lived Group B and the Group C, the Group A referred to production-derived vehicles limited in terms of
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In relation to motorsport governed by the FIA, Group N refers to a set of regulations providing 'standard' production vehicles for competition, often referred to as the "Showroom Class".

This contrasts with the Group A all-out competition production-derived vehicles.
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Mitsubishi Lancer Evolution, colloquially known as the Lancer Evo or simply Evo, is a car manufactured by Mitsubishi Motors. There have been ten versions to date, and the numerical designation of the model is most commonly a roman numeral.
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torque (or often called a moment) can informally be thought of as "rotational force" or "angular force" which causes a change in rotational motion. This force is defined by linear force multiplied by a radius.

The SI unit for torque is the newton meter (N m). In U.S.
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In physics, power (symbol: P) is the rate at which work is performed or energy is transmitted, or the amount of energy required or expended for a given unit of time.
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A Rev limiter is a device fitted to an internal combustion engine to restrict its maximum rotational speed. This is usually carried out to prevent damage to the engine, however sometimes these devices are fitted to prevent an engine reaching the point at which it develops maximum
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Toyota Team Europe (TTE) is a Toyota division based in Köln, Germany. It was recently renamed from Toyota Team Europe to Toyota Motorsport GmbH (TMG). It employs 300 people in a 17000m2 factory and focuses on Toyota's motorsport activities.
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Sport governing body

Category Stock cars
Area of jurisdiction Canada,United States,Mexico
Formation date 1948
Headquarters Daytona Beach, Florida
Charlotte, North Carolina
New York City, New York


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Category Stock car racing
Country or region  United States
Inaugural season
Drivers 49
Teams 22
Engine suppliers 4
Drivers' champion Jimmie Johnson
Teams' champion Hendrick Motorsports

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Sport Auto racing
Founded 1981
No. of teams 25
Country(ies)  Canada
 United States
 Mexico

Most recent champion(s) Kevin Harvick The NASCAR Busch Series is a stock car racing series owned and operated by NASCAR.
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Daytona International Speedway is a superspeedway in Daytona Beach, Florida. It is a 2.5 mile (4 km) tri-oval race track facility with a seating capacity of 168,000 spectators.
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Talladega Superspeedway is a motorsports complex located in Talladega, Alabama. It was constructed in the 1960s in place of abandoned airport runways by International Speedway Corporation, a business controlled by NASCAR's founding France family along with Daytona
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Drafting or slipstreaming is a technique in sports racing where competitors align in a close group in order to reduce the overall effect of drag or fluid resistance of the group in a slipstream.
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Sport governing body

Category Stock cars
Area of jurisdiction Canada,United States,Mexico
Formation date 1948
Headquarters Daytona Beach, Florida
Charlotte, North Carolina
New York City, New York


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Bobby Allison (born December 3, 1937 in Hialeah, Florida) is a former NASCAR Winston Cup driver and was named one of NASCAR's 50 greatest drivers. His two sons, Clifford Allison and Davey Allison followed him into racing, both dying within a year.
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The Aaron's 499 is a NASCAR Nextel Cup stock car race held at Talladega Superspeedway in Talladega, Alabama. The race has always been held in early May or late April.
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