Dirt track racing


Dirt track racing is a form of motorsport held on clay or dirt surfaced banked oval racetracks. Dirt track racing started in the United States before World War I and became widespread during the 1920s and 1930s using both automobiles and motorcycles, spreading throughout Japan and often running on horse racing tracks. There are a myriad of types of race cars used, from open wheel Sprint cars and Modifieds to stock cars. While open wheel race cars are purpose-built racing vehicles, stock cars can be either purpose-built race cars or street vehicles that have been modified to varying degrees. There are hundreds of local and regional racetracks throughout the United States and also throughout Japan. The sport is also popular in Canada, Mexico, Argentina, Brazil, Chile, Australia, New Zealand, South Africa and the United Kingdom.

Racetrack

A dirt track's racing surface may be composed of any soil, although most seasoned dirt racers probably consider a moist, properly prepared clay oval their favorite dirt racing surface. Preparing a dirt track correctly for racing is both a traditional learned craft as well as a long and complex job requiring hours of work. Typical machines used in track preparation include a grader, a cultivator or rototiller, 2 types of rollers and a watering truck, although the process varies at different dirt tracks around the world.
After an event, a track's rutted surface is first graded and smoothed back into the contours of the track's layout. then further smooth and tamp loose soil shoveled into any soft spots. The freshly smoothed track surface is then aerated with a cultivator or rototiller to loosen the now-compacted upper layer and assist with greater water penetration for a moister track on race day. Watering is repeated as necessary according to climate, location and soil composition. Using offset boom nozzles to on water trucks will avoid mashing aerated soil. A dirt track should be rolled and watered as required on race morning with a final light watering, just prior to wheel-packing. Outdoor dirt tracks are typically aerated 12" deep.

North America

Nearly all tracks are oval and less than in length with most being or less. The most common increments in the U.S. are,,,, and. With the longer tracks, the race cars achieve higher speeds up to and the intervals between cars increase. This decreases the chance of crashes but increases the damage and chance of injury when cars do crash.

United Kingdom

In Great Britain the oval tracks are normally on grass with lengths of 400 meters to 800 meters. The races consist of several four lap qualifying heats that eliminate slower drivers. Then there is a final race featuring the fastest competitors.

Europe

In mainland Europe, long tracks can be grass, sand or cinder, and can be up to long.

Australia

Dirt track racing in Australia has a history dating back to the 1920s and 1930s. Most oval track speedways are similar to those in the US for car racing such as sprint cars, speedcars and sedans, with most tracks generally around in length. Most tracks have a clay surface, though some use dolomite, dolomite and clay mix or even sand and clay mix. During the 1970s and early 1980s, a small number of tracks were paved with asphalt, though this phase only lasted about a decade and all tracks paved over eventually reverted to their former surfaces.

Race vehicles

Each racetrack or sponsoring organization maintains a rule book outlining each class of race car which includes dimensions, engine size, equipment requirements and prohibitions. The requirements for each class are usually coordinated with multiple tracks to allow for the widest available venue for each type of car. This coordination allows the drivers to compete at many different racetracks, increase competitors' chances of winning, and lets racing associations develop a series of race events that promote fan interest.
Many tracks support two types of racing in their programs, open wheel cars and stock cars. Both types range from large and powerful V8 engines to small yet still powerful, four-cylinder engines. Some of the smaller open wheel race cars have classes for single-cylinder engines. Depending on the class, the cars may have wings to aid in handling at higher speeds.

Open wheel cars

Open wheel cars are generally manufactured with tubular frames and a body purchased for that particular class. The wheels of these vehicles are not protected by fenders; they are exposed or "open".
Classes include:
  • Dwarf
  • Mod lite - 1000-1250cc motorcycle engines
  • Kart
  • Mini sprint- 600-1200cc motorcycle engines. Usually utilize a top wing.
  • Winged sprint- 410ci, 360ci engine, or 305ci engines. The top wing helps these fast and powerful racecars with downforce.
  • Non-wing sprint car
  • Silver crown
  • Midget
  • Three quarter midget
  • Quarter midget
  • 600 and 270 micro sprints
Open wheel sanctioning bodies include:
  • USAC - The United States Automobile Club
  • World of Outlaws Sprint Cars
  • All Star Circuit of Champions
  • High Limit Sprint Car Series
  • American Sprint Car Series
  • United Sprint Car Series
  • MOWA
  • POWRi
Popular chassis manufacturers around the country for winged sprint cars are Eagle, Maxim, J&J, Triple X, and GF1. There are also several engine builders that build both 410ci and 360ci engines for traveling sprint car teams. Speedway, Kistler, Gaerte, Wesmar, Shaver, Don Ott Racing Engines, and Fisher Racing Engines are the more popular engine builders.

Modified cars

Modified cars are a hybrid of open wheel cars and stock cars. This class of car has the racing characteristics of a stock car. The rear wheels are covered by fenders, but the front wheels are left exposed. There are sanctioning bodies that control the rules for this class at most tracks. Each sanctioning body has their own set of guidelines provided in an annual rule book and their own registration fees. Sanctioning bodies include:
  • Super DIRTcar Series
  • IMCA
  • UMP
  • USRA
  • USMTS
  • WISSOTA
  • TSMA

    Full-bodied cars

Full-bodied cars, sometimes referred to as stock cars, are vehicles that, unlike open-wheel cars, have fenders covering all wheels. Full-bodied cars can vary from full tube frame chassis and aluminum bodied late models to automobiles manufactured by the major automakers with certain modifications as allowed for each class. There are several general types:

Modified production cars

These cars are modified manufactured automobiles. There is a high degree of variability between classes of modified cars. The lowest divisions of modified production cars may be completely stock except for having their interior or windshields removed. The highest divisions of modified production cars may have only a few original stock parts and may be nearly as fast as late model race cars. Most cars have their glass windshields removed and their interiors stripped out. The original seat may be allowed to be used in the lowest classes, but a racing seat and roll cage is required to be installed in higher divisions. Other safety and performance features are added to higher division cars. The engines in lower divisions are completely stock, and higher divisions are highly modified and enhanced. Most modified production cars use full exhaust systems. Engines vary from unmodified 4 cylinders to highly modified V8. Cars in lower divisions use stock tires, and higher division cars use purpose-built specified racing tires.
Common names of modified production car divisions:
  • Limited late model
  • 602/sportsman
  • Pony/mini stocks
  • FWD front wheel drives BJP Racing or B&J Performance is among the highest ranking 4cyl race cars in the country
  • Bombers
  • Cruisers
  • Legends/mod lites
    ''Pure Stock''
These are Full-bodied cars with very few changes allowed from the factory models sold for general use on the streets. Changes can be limited to a certain type of tire, making some parts of the car stronger to withstand the punishment of racing and so forth. All cars used on the race track are required to have a full set of Roll Cages and safety harnesses to protect the drivers. Some tracks have what they call Hornets which are smaller unibody cars with 4-cylinder engines, that must be pretty much as they left the factory except for the roll cage. These would also be considered Pure Stock, but not full sized.
''Street Stock''
These are also Full-bodied cars but can have changes to the frame, engines, tires and some changes to the suspension. They have to have bodies shaped like the actual cars that are used on the street direct from the factory. As with the Pure Stocks cars, all are required to have a full set of Roll Cages and safety harnesses to protect the drivers.
''Super Stock''
Super Stock cars are very similar to Late Models and can be built from the ground up by the racers. They have limited engines and other restricted items that keep them from being full blown Late Models, but they are much more powerful than the Street Stocks and are an intermediate class between Street Stock, Modifieds and Late Models. The bodies are aftermarket or made by the racers in the general shape of the brand being represented.

''Unmodified production cars''

These cars are automobiles just as driven on the street; including the original interiors. The engines may be modified as allowed under different rules: Saloon
Non-production cars
These are stock cars custom built for racing, usually with welded tubular frames and custom built or purchased bodies.
The most popular type of dirt full-bodied stock cars are late models. They are categorized depending on what track and series that is being run. The racetrack dictates what type of late model is raced, but most fall into one of these categories: