Kart racing

Kart racing (as the word is so spelled by enthusiasts) or karting is a variant of open-wheeler motor sport with simple, small four-wheeled vehicles called karts, go-karts, or gearbox/shifter karts depending on the design. By definition a kart must have no suspension (relying on chassis flex), and no differential (solid back axle). They are usually raced on scaled-down tracks, but are sometimes driven as entertainment or as a hobby by non-professionals. Karting is commonly perceived as the stepping stone to the higher and more expensive ranks of motorsports.

Karts were initially created in the United States in the 1950s post-war period by airmen as a way to pass spare time. Art Ingels is generally accepted to be the father of karting. He built the first kart in Southern California in 1956. Karting has rapidly spread to other countries, and it currently has a large following in Europe.

Components

Chassis

The chassis is an extremely important element of the kart, as it must provide, via flex, the equivalent of suspension to give good grip at the front, and must be stiff enough to enable the inside rear wheel to unload in corners. If this did not happen, the grip of the rear wheels trying Kart chassis are also classified as 'open' or 'caged'. Caged karts have a roll cage surrounding the driver, and open karts have no roll cage. Caged karts are not used in Europe.

The stiffness of the chassis enables different handling characteristics for different circumstances. Typically, for dry conditions a stiffer chassis is preferable, while in wet or other poor traction conditions, a more flexible chassis is better- for some karts. For other classes / driving styles, there will be stiffening bars on the kart which are done up tightly for dry and loosened to give more flex for wet conditions. Further complications can be added by changing floorpan materials / fastenings to change the effective stiffness of the chassis.

Professionally raced karts typically weigh 200 to 300 lb (100 to 150 kg). Avanti Kart, Birel and CRG are a few well known examples of the many European manufacturers of race-quality chassis. These usually cost around £1700. American companies in the shifter kart market include: GT Race Karts, Trackmagic and Margay. (List of karting manufacturers)

Motor and fuel

While hobby go-karts depend on gravity for propulsion (these are called soap-box carts or billy karts), racing karts use a small engine. Several types are available, as well as differing fuel options. Gasoline 2-stroke or 4-stroke engines are the most common type, but other types of propulsion are available:

• Engines running methanol (or other alcohol-based fuels)
• Gasoline engines converted to run on propane or methane
• Pressurised gas, using a cylinder carried with the kart
• Electric motors powered by kart-mounted batteries

4-stroke engines are typically standard lawn mower, generator, or even chainsaw engines, sometimes with small modifications, developing from about 5 to 20 hp (4 to 15 kW). Briggs and Stratton and Honda are manufacturers of such engines.

2-stroke engines were originally taken from motorcycles, but have become a kart-specialised item with dedicated manufacturers, Vortex being one example. These can develop from about 16 hp to 30 hp (12 to 22 kW) for a single-cylinder 100 cc unit to 90 hp (67 kW) for a twin 250 cc. The most popular categories worldwide are those using 100 cc engines and the "Touch-and-Go" 125 cc units. A typical 100 cc or 125 cc TaG engine costs around £1500, and a 125 cc gearbox engine about £2000.

Transmission

Karts do not have a differential. The lack of a differential means that the outside rear tire must slide while cornering. Recreational karts have fixed gearing, which in part determines their top speed. They are usually limited to about 60 mph (100km/h) for sprint karts and about 90 mph (145 km/h) for enduro karts. In the very early days karts were direct drive, but the inconvenience of that setup soon led to the centrifugal clutch for the club level classes. At first the clutches were "dry", but the oil bath or "slipper" clutch became common later. These slipper clutches allow the high rpm kart engines to stay higher on their power curve at low speeds, and produce impressive acceleration as they engage. However, the top international classes still use direct drive engines, the reasoning being that at this level drivers should be good enough to stay on the track during the race and hence not need to restart their karts. Unclutched engines will be used at this level until 2007 when the rules will change.

More serious kart racers in the USA prefer shifter karts, which have a six-speed manual transmission and a clutch to make better use of the more powerful engine. Some of these gearboxes are operated with wheel-mounted paddles. In Europe, competitive kart racers tend to prefer fixed gear 100 cc or 125 cc machines although shifters of 125 cc, 250 cc and occasionally 210 cc are also raced. Typical top speeds of racing karts are around 90 mph (145 km/h) for fixed gear and in excess of 160 mph (260 km/h) for the best shifters.

Tyres

Wheels and tyres are much smaller than those used on a normal car. Similar to other motorsports, kart tyres have different types for use appropriate to track conditions:

• Slicks for dry weather. In international level racing these are some of the softest and most advanced tyres in motorsport and a development ground for Formula One.
• Rain tires for wet weather
• Intermediates for damp or low traction conditions. Sometimes worn wet tyres can be used.
• Special, such as spiked tyres for icy conditions

Tyres are sometimes prepared with special solvents to soften them and increase grip, however this is banned by many racing organisations. The tyres can support acceleration round corners at 2 G (20 m/s²), depending on chassis, engine, and motor setup.

Racing

Along with its motorcycle equivalent pocketbike racing, Kart racing is generally accepted as the most economic form of motorsport available. As a free-time activity, it can be performed by almost anybody, and as a motorsport in itself, it is one of the sports regulated by FIA (under the guise of CIK), permitting licensed racing for anyone from the age of 8 onward. In the USA there is not as much FIA involvement.

A variety of kart circuits permit the sport to be practised, although only homologated ones can have official races.

Typically, race formats are one of the following:

Sprint

The sprint format is a series of short-duration races, normally for a small number of laps, that qualify for a final, with a variety of point scoring calculations to determine the event's overall winner. Typical duration does not normally exceed 15 minutes. Here, speed and successful passing is of the most importance. It normally occurs in the format of three qualifying heats and a final race for trophy positions.

The FIA championships, including the World Kart Championship, take place in this format.

Endurance

Endurance races last for an extended period, from 30 minutes up to 24 hours or more, for one or more drivers. In general, consistency, reliability, and pit strategy is of greater importance than all out speed.

Categories

There are many different classes or formulae in karting. The FIA sanctions international championships in JICA, Intercontinental A, Formula A, Intercontinental C, Super ICC and Superkart Division 1 and Division 2. These are regarded as the top levels of karting and are also raced in national championships.

Many people race in Spec series such as Rotax Max (a Touch-and-Go class), Formula TKM or those using the Yamaha KT100 engine, and Cadet classes for ages 8 to 12 are usually popular.

In the United States, the biggest proportion of racers are in the dirt oval classes which often use Briggs & Stratton industrial engines.

Karting as a learning tool

Kart racing is usually used as a low-cost and relatively safe way to introduce drivers to motor racing. Many people associate it with young drivers, but adults are also very active in karting. Karting is considered the first step in any serious racer's career. It can prepare the driver for high-speed wheel-to-wheel racing by helping develop quick reflexes, precision car control, and decision-making skills. In addition, it brings an awareness of the various parameters that can be altered to try to improve the competitiveness of the kart (examples being tyre pressure, gearing, seat position, chassis stiffness) that also exist in other forms of motor racing.

As well as "serious" competitive kart racing, many commercial enterprises offer casual hire of karts. Such karts are usually powered by small, detuned four-stroke engines and are far slower than the fully-fledged competitive versions.

Many, perhaps most Formula One racers grew up racing karts, most prominent among them Michael Schumacher, Ayrton Senna and Mika Häkkinen. Many NASCAR drivers also got their start in racing from karts, such as Darrell Waltrip, Lake Speed, Ricky Rudd, Tony Stewart, and Kyle Petty.

A popular video game rendition is the Mario Kart series. Also, many childrens video game racing titles (i.e. Crash Team Racing and Konami Krazy Racers) feature karts as the main vehicles.