- 1,099
- Texas
- Whiskey345ci
The purpose of this thread is to distiguish the fact and here-say of the JGTC/SuperGT ristrictions and regulation. I have notice some people stressing the wrong information. Hopefully this thread will help all that have the wrong information on SuperGT regulations. Not understanding the use of the terms "base" and silhoutte has led to mass confusion. Theres also been false sources of information. Some believe that JGTC cars are not based off factory vehicles. I have posted and broken down the regulations in other threads but it was an off topic subject. So I will dedicate this thread to be used as a broken down and easy to comprehen reference link for those who want to know the facts and educate themselves on these vehicles.
Note: All that is stated below is directly quoted from the Official SuperGT regulation/restriction Digest. accept what is highlighted in GREEN. The main focus is structural attributes and to support the fact that these cars are based of there factory versions/ on factory frames/skeletal structure and chasis. Thus aerodynamics, air ristricters, weight, steering, brakes, wheels/tires, drivetrain, fuel tank/systems, lights or anything irrelevant to the structure of the vehicle wont be covered but can be found on there website; Supergt.net
Original Vehicle
Definition of a Grand Touring Car:
Automobile having at least 2 seats and one door on each side respectively for getting in and out of the vehicle.
Vehicle type eligibility:
Cars must be homologated to FIA Group N, A, N-GT, GT2, JAF Production Touring Cars or Special Touring Cars, or otherwise be registered with JAF as registered vehicles.
Material restrictions
Composite materials (Including carbon and kevlar):
Permitted in the relevant parts or areas if authorized in the regulations, or used as standard on the original car and original engine.
Titanium and ceramics:
Apart from connecting rods, intake and exhaust valves, valve retainers, heat shields, brake caliper pistons and superchargers, titanium and ceramic materials can be used on specific areas of the car, but only if these materials are used as standard on the original vehicle and engine.
Control function restrictions:
Any automatic or electronic chassis control system or function is forbidden, even if standard on the original vehicle. A simple open-loop electrical switch activated by the driver acting on a system is not considered to be an electronically controlled system.
Engine
Type and position of engine:
An engine which is produced by original manufacture and is legal for road use, and admitted by FIA and/or JAF can be mounted.
The mounting position, location and orientation of the engine are without restriction provided the engine is situated within the engine compartment of the original vehicle.
Engine modifications:
Modifications to cylinder capacity are permitted. Supercharging devices are also allowed. Reinforcement of cylinder head and cylinder block is permitted. Crankshaft and connecting rods modifications are unrestricted. Modifications to camshaft position/number and changes to the driving system are not permitted. Intercoolers for cooling the intake air including its mounting position and piping are unrestricted. The exhaust system is also without restriction. However, variable exhaust systems are not permitted. Supercharging is not allowed when a 3-rotor engine is used on a GT300 vehicle. The exhaust mouth must be 300 mm or more above flat bottom.
*Laymans Terms: Factory engine may be used long as the above apply. Vehicles may use other motors besides the factory as long as its made by the same manufacturer, street legal, and permitted by FIA and or JAF.
Bodywork
Dimensions:
Except for modifications as permitted by the regulations, all bodywork dimensions and shape must remain original, and must be in accordance with the data shown on the homologation forms and documents of the registered vehicle. Ground clearance is measured from every direction of the complete vehicle perimeter and must be at least 50mm from the ground. Any and all suspended parts cannot be situated below this height. Front and rear overhang as well as wheelbase dimensions must be identical to those of the original vehicle. However, cars having an overhang of less than 900mm are allowed to extend the overhang by a maximum of 80mm, but never to exceed 900mm.
Windshield & Windows:
The front windshield must be in accordance with the rules under "Safety regulations for homologated cars and registered vehicles" in the JAF regulations. The front windshield glass may be replaced with polycarbonate of a thickness greater than 6mm and which permits the cockpit interior to be visible, provided the same installation position and shape as the original glass is maintained.
Changes in bodywork materials:
Composite materials and light metals may be substituted for front and rear bumper, fender, door, bonnet, rear hatch gate and boot-lid components provided that these substitutions maintain enough structural strength and do not result in configurative changes. Louvers, ribbing or lips etc. may be installed, if they do not significantly alter the external appearance of the vehicle (maximum protrusion allowed is 20mm).
Bodywork (monocoque structure) and bulkhead:
Bulkhead and cockpit areas must not differ from the original vehicle specifications (monocoque structure), and the bulkhead must not be modified except as permitted by the regulations. However, modifications to the bulkhead for reinforcement purposes are permitted.
Further, openings may be made for the purpose of connecting the tubular structure defined under the regulations below to the rollcage.
Bodywork structure fore of the front bulkhead and hind of the rear bulkhead:
Main structure (structural framework) situated fore of the front bulkhead and hind of the rear bulkhead may be cut and replaced by a tubular structure that is connected to the rollcage. In this case, it is obligatory to install a crushable structure defined under the regulations.
**Laymans terms: The frame of the vehicle may be modified to accomodated the rollcage, or further reinforce.
Fenders:
On each side of the car, fender dimensions may be extended (increased in width) up to 5cm over the width of the original vehicle, but the maximum width must not exceed 200cm.
The front part of the front fender and rear part of the rear fender must fit within the area defined under the regulations as viewed from above.
***Note: These body dimensions are increased but have nothing to do with the structure of the vehicle. Compare structure to your skeleton, and body panels to your skin or clothing. Theres nothing you can cosmetically do to change your bone structure, except break it/them. This applies to the frame and or chasis of a factory based SuperGT vehicle
Hard tops for open-top cars:
Hard tops may be installed for open-top cars. But the hard top must maintain its configuration and be similar to the original. Use of material is unrestricted.
Suspension
Suspension type on the original vehicle may be freely modified and altered. However, if the suspension mounting points on the chassis/monocoque are modified, the suspension must still work normally when the engine has been dismounted. All suspension arms must be made of metallic materials. Spring and shock-absorber are free of restriction.
Adjustment of anti-rollbars can be made mechanically only by the driver, and only when the car is in motion. Anti-rollbar adjustment by any other means is not permitted when the car is in motion
Specific regulations for 4-door vehicles
Definition of 4-door cars:
Cars having 2 doors on each side for getting in and out of, where a 2-door model does not exist in the family (applied to Group A cars of Article 255 of Appendix J) of the model concerned and approved by the ASN (national body, recognized by the FIA. ie: JAF).
Rear doors:
Rear doors may be extended in their width. They may be identical to the extended outer surface of the rear fender. However, the configuration of the car when viewed from the side must be maintained, other than the part cut for the forming of wheel arches. The opening/closing function for rear doors is unrestricted.
Bodywork structure around rear doors:
It is permissible to process or modify the main bodywork (monocoque construction) such as an outer sill in order to accommodate rear complete wheels within the limitations and conditions in the regulations.
Rear window glass:
It is not permitted that the shape of the rear window glass be modified, but its operating function does not need to be maintained.
****Yes: Infact JGTC/SuperGT cars ORIGINATE from there factory counterparts. I wont use the word "based" any longer, and definetely not the word "silhoutte" (which I never have) as some know and have stated these terms are very loose. Which is probably the reason they arent used in the actual regulation content/digest.
Once again this is to be used as a link for those that want to know rather JGTC/SuperGT cars are factory based and general information on the structure and chasis. Everything was quoted straight from the Official Technical Regulation Digest. It should settle many pointless arguments but sometimes fact from a credible source is not good enough (dont ask why) but ENJOY! 👍
Note: All that is stated below is directly quoted from the Official SuperGT regulation/restriction Digest. accept what is highlighted in GREEN. The main focus is structural attributes and to support the fact that these cars are based of there factory versions/ on factory frames/skeletal structure and chasis. Thus aerodynamics, air ristricters, weight, steering, brakes, wheels/tires, drivetrain, fuel tank/systems, lights or anything irrelevant to the structure of the vehicle wont be covered but can be found on there website; Supergt.net
Original Vehicle
Definition of a Grand Touring Car:
Automobile having at least 2 seats and one door on each side respectively for getting in and out of the vehicle.
Vehicle type eligibility:
Cars must be homologated to FIA Group N, A, N-GT, GT2, JAF Production Touring Cars or Special Touring Cars, or otherwise be registered with JAF as registered vehicles.
Material restrictions
Composite materials (Including carbon and kevlar):
Permitted in the relevant parts or areas if authorized in the regulations, or used as standard on the original car and original engine.
Titanium and ceramics:
Apart from connecting rods, intake and exhaust valves, valve retainers, heat shields, brake caliper pistons and superchargers, titanium and ceramic materials can be used on specific areas of the car, but only if these materials are used as standard on the original vehicle and engine.
Control function restrictions:
Any automatic or electronic chassis control system or function is forbidden, even if standard on the original vehicle. A simple open-loop electrical switch activated by the driver acting on a system is not considered to be an electronically controlled system.
Engine
Type and position of engine:
An engine which is produced by original manufacture and is legal for road use, and admitted by FIA and/or JAF can be mounted.
The mounting position, location and orientation of the engine are without restriction provided the engine is situated within the engine compartment of the original vehicle.
Engine modifications:
Modifications to cylinder capacity are permitted. Supercharging devices are also allowed. Reinforcement of cylinder head and cylinder block is permitted. Crankshaft and connecting rods modifications are unrestricted. Modifications to camshaft position/number and changes to the driving system are not permitted. Intercoolers for cooling the intake air including its mounting position and piping are unrestricted. The exhaust system is also without restriction. However, variable exhaust systems are not permitted. Supercharging is not allowed when a 3-rotor engine is used on a GT300 vehicle. The exhaust mouth must be 300 mm or more above flat bottom.
*Laymans Terms: Factory engine may be used long as the above apply. Vehicles may use other motors besides the factory as long as its made by the same manufacturer, street legal, and permitted by FIA and or JAF.
Bodywork
Dimensions:
Except for modifications as permitted by the regulations, all bodywork dimensions and shape must remain original, and must be in accordance with the data shown on the homologation forms and documents of the registered vehicle. Ground clearance is measured from every direction of the complete vehicle perimeter and must be at least 50mm from the ground. Any and all suspended parts cannot be situated below this height. Front and rear overhang as well as wheelbase dimensions must be identical to those of the original vehicle. However, cars having an overhang of less than 900mm are allowed to extend the overhang by a maximum of 80mm, but never to exceed 900mm.
Windshield & Windows:
The front windshield must be in accordance with the rules under "Safety regulations for homologated cars and registered vehicles" in the JAF regulations. The front windshield glass may be replaced with polycarbonate of a thickness greater than 6mm and which permits the cockpit interior to be visible, provided the same installation position and shape as the original glass is maintained.
Changes in bodywork materials:
Composite materials and light metals may be substituted for front and rear bumper, fender, door, bonnet, rear hatch gate and boot-lid components provided that these substitutions maintain enough structural strength and do not result in configurative changes. Louvers, ribbing or lips etc. may be installed, if they do not significantly alter the external appearance of the vehicle (maximum protrusion allowed is 20mm).
Bodywork (monocoque structure) and bulkhead:
Bulkhead and cockpit areas must not differ from the original vehicle specifications (monocoque structure), and the bulkhead must not be modified except as permitted by the regulations. However, modifications to the bulkhead for reinforcement purposes are permitted.
Further, openings may be made for the purpose of connecting the tubular structure defined under the regulations below to the rollcage.
Bodywork structure fore of the front bulkhead and hind of the rear bulkhead:
Main structure (structural framework) situated fore of the front bulkhead and hind of the rear bulkhead may be cut and replaced by a tubular structure that is connected to the rollcage. In this case, it is obligatory to install a crushable structure defined under the regulations.
**Laymans terms: The frame of the vehicle may be modified to accomodated the rollcage, or further reinforce.
Fenders:
On each side of the car, fender dimensions may be extended (increased in width) up to 5cm over the width of the original vehicle, but the maximum width must not exceed 200cm.
The front part of the front fender and rear part of the rear fender must fit within the area defined under the regulations as viewed from above.
***Note: These body dimensions are increased but have nothing to do with the structure of the vehicle. Compare structure to your skeleton, and body panels to your skin or clothing. Theres nothing you can cosmetically do to change your bone structure, except break it/them. This applies to the frame and or chasis of a factory based SuperGT vehicle
Hard tops for open-top cars:
Hard tops may be installed for open-top cars. But the hard top must maintain its configuration and be similar to the original. Use of material is unrestricted.
Suspension
Suspension type on the original vehicle may be freely modified and altered. However, if the suspension mounting points on the chassis/monocoque are modified, the suspension must still work normally when the engine has been dismounted. All suspension arms must be made of metallic materials. Spring and shock-absorber are free of restriction.
Adjustment of anti-rollbars can be made mechanically only by the driver, and only when the car is in motion. Anti-rollbar adjustment by any other means is not permitted when the car is in motion
Specific regulations for 4-door vehicles
Definition of 4-door cars:
Cars having 2 doors on each side for getting in and out of, where a 2-door model does not exist in the family (applied to Group A cars of Article 255 of Appendix J) of the model concerned and approved by the ASN (national body, recognized by the FIA. ie: JAF).
Rear doors:
Rear doors may be extended in their width. They may be identical to the extended outer surface of the rear fender. However, the configuration of the car when viewed from the side must be maintained, other than the part cut for the forming of wheel arches. The opening/closing function for rear doors is unrestricted.
Bodywork structure around rear doors:
It is permissible to process or modify the main bodywork (monocoque construction) such as an outer sill in order to accommodate rear complete wheels within the limitations and conditions in the regulations.
Rear window glass:
It is not permitted that the shape of the rear window glass be modified, but its operating function does not need to be maintained.
****Yes: Infact JGTC/SuperGT cars ORIGINATE from there factory counterparts. I wont use the word "based" any longer, and definetely not the word "silhoutte" (which I never have) as some know and have stated these terms are very loose. Which is probably the reason they arent used in the actual regulation content/digest.
Once again this is to be used as a link for those that want to know rather JGTC/SuperGT cars are factory based and general information on the structure and chasis. Everything was quoted straight from the Official Technical Regulation Digest. It should settle many pointless arguments but sometimes fact from a credible source is not good enough (dont ask why) but ENJOY! 👍
