Regulations on the JGTC

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    Contributed by : Chan Eu Jin

    There are two categories in the All Japan Grand Touring Car Championship: GT500 (approximately 500hp) and GT300 (approximately 300hp). Complying with the technical regulation of the Japan Automobile Federation (JAF), the cars are greatly modified from the originals. To keep the battle close through every lap of every race, technical regulations were established to maintain equilibrium among each car’s capability. With minimum weight and air restrictors that the cars must be fitted with, performance is strictly controlled to keep the field closer together. Listed below are some of the regulations on the JGTC: -

    The engine can be charged if it is the same make production engine. The position and installation of the engine are free in the engine as long as the original location and orientation are retained. The engines of most cars are installed so as to sit as low as possible, and as near to the center of the car as possible. Turbochargers may be fitted or removed.

    Air Restrictors
    Cars must be fitted with air restrictors, which are devices to control the intake air for the engine to maintain equal performance among the competitors. However, a well-tuned engine still has an output of a full 500 or 300hp.

    The type of braking system used is not regulated. However, anti-lock braking system are not allowed to be used.

    Maximum width (complete wheel)
    · GT500 : 14” (359mm)
    · GT300 : 12” (305mm)
    Maximum diameter (compete wheel)
    · GT500 : 28” (711mm)
    · GT300 : 28” (711mm)

    One of the keys to the supremacy of speed in JGTC is a car’s suspension. The only regulation here is that the car’s original suspension configuration is to be used.

    Bodywork and Aerodynamic
    Any modifications to the bodywork must resemble the original panels as nearly as possible. The engine hood, trunk lid and car doors may be replaced by parts made of fiber-reinforced plastic or lightweight alloys. The width of the bodywork across the front and rear wheel arches can be increased by 5cm on each side. Front spoilers and rear wings are permitted. There are no restrictions regarding the materials to be used for making the spoiler or rear wing, but sizes for these components are controlled. The use of rear diffuser can be used as well.

    As JGTC is comprised of semi-endurance races, two drivers in turn take the wheel of one car. The maximum continuous time behind the wheel per driver is 1/3 of the race distance.

    Races are started using the “rolling start” format. Car location on the starting grid is based on the order of the fastest to slowest qualifying times, front to rear of field, respectively. A formation lap is conducted with the field following behind a pace car. When the field has obtained proper form and spacing, the pace car leaves the track and the green light is given to start the race.

    Read also:

    Japan GT Festival in Malaysia
    The Race
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