Group ND Proposal

Engine Block and related

The engine block may be original for the model or changed to a later casting/version from the same manufacturer of the vehicle model, provided it :-

• Is made from the same type of material, eg Aluminium alloy or cast iron
• Has identical cylinder bore, crank stroke and crankshaft tunnel sizes
• Has identical main cap fixtures and locations
• Has identical cylinder head fixtures and locations
• Accepts the original camshaft drive system, oil pump, ignition distributor (if fitted to the block)
• Accepts identical engine mounting and support brackets
• Has the same engine model code allocated by the manufacturer

All rotating and reciprocating parts inside the engine block are free save that the crankshaft stroke cannot be altered

The engine mechanical water pump and its drive system is free . Cooling system hoses are free .

Balancing, coating, polishing, surface refinishing , electroplating and heat treatment of any internal component is free.

The block must not be externally altered by grinding off unwanted segments, brackets, manufacturer Identification marks etc.

Cylinder Head

The cylinder head may be a later casting/version from the same manufacturer or a more modern reproduction or performance oriented alternative that may have different size or shape ports. any replacement cylinder heads must also directly mate to original block using original studs/bolts/dowels and also original intake and exhaust manifolds must fit directly to them.

Emission control devices such as EGR valves, are free.

Cylinder head porting is free.

Valve Actuation

Any valve operation system may be freely modified to allow adjustment of the static timing, however the basic method of operation must not change, eg chain drive cannot be swapped for belt drive or gear drive or vice-versa. Belts, chains and tensioning devices are otherwise free.

Valves, valve springs,  rocker arms , rocker pedestals , cam buckets , retaining collets and any related packers or shim, are free . Any variable cam timing or valve lift system is free.

Justification and Rationale

The combination of Group N general requirements plus the Na to Nc requirments are seen as too proscriptive and detrimental to wider competitor uptake, especially for a newer cohort or racers with a new generation of more complex vehicles, many of which already compete in speed events like Sprints & Hillclimbs, where few technical requirements exist.

Many of the period MODEL have a vast range of competition parts already available off the shelf

The suggested new Nd rules are more complex because the cars and engines of Nd era are more complex with widespread introduction of multiple overhead cams, electronic injection, turbocharging etc and the nature of modifications not commonly seen on older cars.

A balance has been sought between trying to stay largely “original”  (which can drive up costs) and  having extensive freedoms to swap engines akin to Sports Sedans  or even 3J IP .