Fuel System modifications Group C v 5th Cat v ND

CAMS Manual Group C 1973: Fuel used shall be commercial fuel as defined

5th Category Specific Requirements Group C Touring 2025:

Only the following fuel is permitted:

1. Pump Fuel as defined by the Manual Technical Appendix Schedule G; or
2. Unleaded Racing Fuel as defined by The Manual Technical Appendix Schedule G except that the following higher specifications are permitted:
   1. Up to a maximum RON of 104; and
   2. Up to maximum of 3.7% Oxygen by volume (v/v)

CAMS Manual Group C 1973: 

1. The use of safety type fuel tanks (either "bladder" or "Synthetic" types) is permitted, provided that neither the location, general appearance or method of filling is altered
2. The capacity of such a safety tank may be greater or less than that  fitted by the manufacture, provided always that the capacity does not exceed that promulgated in appendix C, part 14 ("Fuel Tanks")
3. The fitment of a one-way valve on the fuel tank inlet for fuel ventilation (maximum breather outlet not to exceed1/2" internal diameter) and designed to prevent the egress of fuel in the case of an accident is permitted, provided that the diameter of the fuel tank inlet or port is not increased beyond original specifications.

The Group C rules should not be utilised as the current 5^th Category requirements are suitable for todays needs.

The fuel tank should follow the current 5^th Category requirements which allows for the fitment of commonly available aluminium or plastic fuel cells which typically comply with the following Motorsport Australia schedule. 

Technical appendix schedule N – Fuel Tanks

Such commonly available fuel cells are usually sold with an appropriate one-way breather valve designed to prevent egress of the fuel in the case of an accident (rollover).

Filler neck and filler orifice sizes are both redundant in 5^th Category races as there are no events where refuelling during the event is required. So no perceived advantage can be gained by altering the filler neck or filler orifice.

CAMS Manual Group C 1983: 

1) Safety Bladder Tanks

1. The installation of an FIA approved bladder type tank is permitted provided that it is installed in the general location of the original tank and panel modifications are in accord with paragraph9 or part 14 appendix C.
2. The capacity of such safety tank may be varied from that fitted by the manufacturer of the car, provided always that the capacity does not exceed that nominated in paragraph 10 part 14 appendix C

2) Foam filled Tanks

1. The fitment of a one-way valve on the fuel tank inlet for fuel ventilation (maximum breather outlet not to exceed13mm internal diameter) and designed to prevent the egress of fuel in the case of an accident is permitted, provided that the diameter of the fuel tank inlet port is not increases beyond the original specification.
2. The fuel filling port may be relocated on those cars which have a foam filled fuel tank. In the event of relocation:
   1. the filler orifice shall be located not more than 50mm from the tank.
   2. Original fuel port shall be rendered inoperative
   3. No Panel modifications are permitted save that the floor of the luggage boot may be modified to allow the protrusion of the filler neck.
   4. Regardless of the number of original fuel ports one port only may be utilised and this shall have no greater diameter than that of the original filler orifice; and in the case of cars fitted originally with multiple fuel ports, one of the original filler orifices. 

5th Category General Requirements 2025:

Fuel tanks: The fitment of a foam-filled fuel tank, or a fuel tank of a safety type approved by the FIA to FT3 specifications, is highly recommended refer the Manual Technical Appendix Schedule N. Where such a fuel tank is fitted, it should be installed either:

(i) in the same location as the original fuel tank, whereupon the original tank may be removed; or

(ii) as near as practicable to the retained original fuel tank. In this instance the original fuel tank must be fully drained of any liquid, cleaned and rendered totally fuel vapour free, any drain plug must be removed, and the tank must be adequately vented. The filler neck must be isolated to prevent accidental re-filling.