9.4. Category 2. Any Vehicle not complying with Arts. 9.3. a – d above that may be authorised for use at the discretion of the ASN including Vehicles homologated and remaining fully compliant with FIA R / GT regulations.
a.
Such authorisation will only be granted for Vehicles which retain the original manufacturer’ s Chassis / bodywork / unitary construction.
b. |
Substitution by a space frame Chassis will not be accepted. |
c. |
Original manufacturer ' s bodywork must be utilised. |
d. |
Any modifications homologated by the FIA may be incorporated. |
e. |
Replica copies of manufacturers homologated body parts / aerodynamic devices will not be accepted. |
f.
g.
h.
Manufacturers of very low volume numbers of Vehicles will be able to apply for baseline specification registration prior to sale to individual customers.
The conversion of front wheel drive Vehicles to rear wheel drive( or four wheel drive) or of rear wheel drive Vehicles to four wheel drive is permitted subject to the bodyshell construction alterations from the bulkhead rearwards being limited to those detailed in FIA Art. 279.10.3.10 and shown in FIA Appendix J Drawings 279-1 and 279-2. Additionally where rear wheel drive Vehicles are converted to four wheel drive the bodyshell forward of the front bulkhead may be modified solely to allow fitment of front driveshafts.
All materials added must be ferrous and must also be welded to the Chassis / bodywork / unitary construction.
i. Doors and windscreen must remain in the manufacturer ' s original material. j. Cars must be fitted with an engine in compliance with Arts. 9.4. k – t below. k. Production Car Engines: i.
ii.
iii.
iv.
Petrol engines with a maximum of six cylinders, forced induction up to 2000cc with a 34mm restrictor or up to 2500cc with a 32mm restrictor, and diesel engines with forced induction up to 2500cc with a 37mm restrictor. Naturally aspirated with a maximum of six cylinders, and more than 2 valves per cylinder – up to 3000cc. Naturally aspirated with a maximum of six cylinders, and a maximum of 2 valves per cylinder – up to 3500cc Rover V8 pushrod engines up to 4000cc, utilising the original Rover head castings, and limited to either a maximum of 4 carburettor chokes or a single throttle body and the original plenum chamber. l.
Metro 6R4 2500cc and 2800cc( Single Plenum) engines complying with MSA Specification, exclusive to 6R4s.
m. Specialist Competition Engines: i. Naturally aspirated. ii. No more than four cylinders. iii. No more than four valves per cylinder. iv. Maximum capacity of 2,500cc. n. Production Car Engines with a maximum of 2 rotors.
i. Rotary engine equivalence 1.7. Forced induction rotary engines equivalence( 1.7. x 1.7.) = 2.89. ii.
Rotary engines will be considered equivalent to 4 valves per cylinder petrol engines in respect of the maximum engine capacity including the application of equivalency factor( a) above.
Motorsport UK National Competition Rules 2026 Edition 1
Chapter 16 Part A( Autocross and Clubcross) Appendix 5- Technical Regulations
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