b. |
A maximum of two carburettor chokes( two single or one double). |
c. |
A maximum of one camshaft per bank of cylinders. |
3.2. |
Engines with more than one camshaft per bank of cylinders may be used providing that: |
a. |
any replacement engine comprises a block and cylinder head from the same engine family. |
b. |
they were originally fitted with fuel injection, and; |
c. that fuel injection system complete with the inlet manifold and throttle body is retained unmodified except as permitted in Art. 2.3. c.
3.3. It is permitted to make the following modifications to effect installation;
a. alternative engine mountings, sump pan and exhaust manifolds are permitted; b. it is permitted to relocate ancillaries such as alternators and steering pumps. c. it is permitted to change the orientation of the otherwise unmodified inlet manifold provided it is fitted directly to the cylinder head without the addition of an intermediate adapter device.
3.4. For petrol engines under 1500cc and diesel engines under 2000cc actual capacity, forced induction is permitted providing that the complete original induction system is retained unmodified and other than the replacement of the air filter element.
3.5. Fuel injection may be fitted where it was standard equipment by the manufacturer for that engine type and where the original plenum chamber and throttle body is retained for that engine type.
3.6. A standard Wankel unit will be considered as three cylinders – twin Wankel units are prohibited.
3.7. Engines must comply with the silencing levels Ch. 5 App. 8, Ch. 7 App. 8 Art. 2 and App. 1 Art. 7 of this Chapter and have induction air filter elements fitted that ensure the Vehicle complies with noise regulations Ch. 7 App. 8 Art. 2.
3.8. The only type of manual transmission permitted is an H shift pattern. The gear lever must remain the only means of changing gear unless an alternative method was originally fitted by the Vehicle manufacturer as standard. Automatic transmissions are permitted provided that they are in their original configuration as fitted by the manufacturer to that specific Vehicle model.
3.9. The number and location of the driven wheels must remain as original to the model of car.
4. Wheels and Tyres
4.1. Wheels and tyre sizes are free but must fit within the standard unmodified wheel arch. A maximum of six tyres can be used by a crew during an Event unless the Official Documents state otherwise.
4.2. Vehicles must be fitted with tyres that are always legal for use on the Public Highway. 4.3. Tyres must comply with Ch. 8 App. 4 Art. 3.1.
4.4. Vehicles must have all spare wheels securely fastened in position and must not be fitted with spiked or studded tyres or any non-skid attachments, other than chains if permitted by Official Documents.
5. Electrical Systems
5.1. Vehicles must have a maximum of four forward facing beams, as well as side and indicator lights, unless further restrictions are specified in Official Documents. Where more than four beams are fitted as standard, only four may be used and the remainder must be rendered unusable for the duration of the Event.
5.2. Light pods are not permitted. 5.3. A headlamp must provide the main beam and dipped beam functions.
5.4. An auxiliary lamp provides a beam other than that provided by the headlamp. With the exception of Vehicles built before 31st December 1946 the maximum width of the lamp body of any auxiliary lamp must not exceed 222mm.
Motorsport UK 2025 National Competition Rules Version 11
Chapter 13 Appendix 11 Part C- Specific Regulations for Targa Road Rallies
479