Category 2 Porsche 911

Permitted modifications supported by documented evidence. 

Engine.
2.0 80×66 =1991cc. 2.2 84×66.2 = 2195cc. 2.4 84×70 = 2341cc2.7 90×70.4 = 2687cc  3.0 95×70.4 = 2994cc
Mechanical timing chain tensioners only. 

Ignition/Electrics.
Electronic ignition. 

Carburation/Fuel system
Bosch Mechanical injection on 2.7 & 3.0lt engines.
Carburettors. Solex, Zenith, Weber, PMO.
Electric fuel pump. 

Engine Oil Coolers and system.
The oil tank is mounted in the rear inner wing. Not in the engine compartment.
The external oil cooler is mounted in the front of the vehicle.
The factory fitted the cooler in the front right hand inner wing area behind the headlamp or in the centre of the front bumper assembly.
The coolers were a serpentine or loop style. The use of a multi row radiator (Serck) is also permitted.
There is no evidence to support the fitment of the engine oil cooler in the rear spoiler or within the engine compartment. 

Exhaust System.
The Exhaust headers may have the heat exchanger boxes removed. They must retain the two, two bolt flange fittings to the rear silencer box.The rear transverse silencer may have two or a single side exit outlet pipe. 

Gearbox.
4 or 5 Speed.  901 or 905 all synchromesh type of gearbox. ZF Plated type, Limited Slip Differential 

Clutch. 

Suspension. 

Front.
Period design Telescopic shock absorbers.

Rear.
Peiod  design Telescopic shock absorbers.Non adjustable rear spring plates. 

Brakes.
The fitting of a dual master cylinder or any other type of device providing a simultaneous action on all four wheels and divided action on two wheels is permitted providing the original brake pedal and pivot point are used. The remote brake bias adjuster must be positioned so that it cannot be adjusted by either the driver or co-driver when normally seated in the car.
Front. Vented front brake discs. Twin piston brake callipers.
Rear:  Solid or vented rear brake discs. Twin piston brake callipers mounted at the front of the brake discs. 

Brakes 3.0Lt engined cars.Cross drilled vented brake discs.  The brake callipers used on the 911 Turbo 3.3 litre are allowed as a replacement for the original period brake calliper as fitted to the 3litre Carrera RS/RSR.
The Rear brake callipers are mounted at the rear of the trailing arm assembly. This is the opposite side to normal.  
Wheels and Tyres.
Fuchs, Minilite or period design wheel rims.

Tyres and rim width as per MSA Blue book.

General.
A replacement Alloy fuel tank or FT3 safety fuel cell is permitted.
Fibre glass bonnet and boot lid.
Composite side windows.
Digital display dashes and instruments are not permitted.