This is the section from the SCTA rulebook about fire systems. Maybe it will give you some guidence.
3.Q FIRE EXTINGUISHING SYSTEMS:
All cars and enclosed motorcycles shall have a minimum of one driver-controlled fire extinguishing system using a minimum of 5 lbs. of extinguishing agent designed and applied to function as driver protection. Approved agents include Halon 1301, Halon 1211, DuPont FE36, and certain AFFF systems including Cold Fire 302, ESS Foam, Firefox Gem Foam or other Halon replacement certified by the manufacturer for use in a confined space. Dry chemical and CO2 may be used in the engine compartment only. The application and installation shall be in accordance with the manufacturer’s recommendations for the size and shape of the driver’s compartment. The discharge rate should be designed to allow sufficient protection for the time it will take the car to stop from speed.
NOTE: Care and consideration shall be taken to prevent driver suffocation. Fresh air venting or breathing systems may be necessary.
ALL CARS and MOTORCYCLE STREAMLINERS, 0-200 MPH shall have a total of 10 lbs. extinguishing agent onboard. At least 5 lbs. must serve the driver/rider area and the additional 5 lbs. may serve the engine and/or a combination of driver/rider and engine areas. Both areas shall be served via fixed nozzles. Acceptable agents in the engine area include CO2, foam, Halon, a Halon replacement or dry chemical. The engine system shall generally include 2 nozzles directed toward the header/oil pan area or be installed according to manufacturer's recommendation. Only Halon or Halon replacement agents may be used in the driver’s compartment. See above paragraph.
ALL VEHICLES OVER 200 MPH, because of the additional time required to stop, shall be equipped with additional extinguishing agent (in addition to the 5 lbs. minimum) which is designed and fitted for driver protection. The installation should be commensurate with driver compartment size and the speed of the vehicle. Contact a reputable safety equipment manufacturer for installation advice.
Minimum Agent Requirements:
0-200 MPH 10 lbs. min. Driver & engine
201+ MPH 11 lbs. min. Over 5 lbs. for driver
NOTE: The amount of required agent should not be confused with total bottle weight.
All push/recovery/support vehicles are required to have a minimum of one 4 lb. portable fire extinguisher.
All competition vehicle extinguishing system control valves shall be within the reach of the driver while strapped in position. The valves shall be designed to remain open once actuated. All agent lines and nozzles shall be metal and securely mounted. Extinguishing agent cylinders within the driver’s compartment shall be mounted with a system more substantial than hose clamps alone. The use of hose clamps as a primary mounting system is prohibited.
A current inspection/filling certification (no more than 24 months old) for each agent bottle shall be visible to the technical inspector without removing the bottle.
NOTE: Agent delivery lines are subject to dust and moisture clogging. Participants are responsible to assure that the fire system is full and operable before each event. Frequent clearing of the lines is recommended. Aqueous foam systems require that the nozzles be directed appropriately so that the agent does not impede the vision of the driver. Questions concerning fire-extinguishing systems may be directed to the Fire Extinguishing System Specialist, section 16.
DW