The C series range of 911s saw the model’s first increase in engine capacity, from 1991cc to 2195cc – commonly referred to a 2.2-litres. This was achieved by increasing the cylinder bores from 80mm to 84mm. At the same time, other minor improvements were made to the engine, including revised cylinder heads with larger valves and stronger connecting rods.
The upshot of these improvements meant that the 911E’s engine now produced 155bhp. More importantly, though, the torque was increased and the torque curve was flatter, thus making the engine more flexible and the car easier to drive. No longer did you have to keep the revs up high to have fun! A larger, 225mm diameter clutch was fitted to cope with the extra power.
In an effort to reduce weight, the E was given aluminium central bumper sections and an engine compartment cover of the same material. The body itself was given a PVC underseal as protection against corrosion.
The interior remained largely unchanged, although there were detail changes. The most significant was that the instruments now had neoprene retaining rings around them, so that they could easily be removed – earlier cars used an inaccessible rear bracket to locate the dials. This simple solution was to remain right to the end of the air-cooled cars. Also new were modern-type stalk switches for indicators, headlamp dip/flash and windscreen wash, and larger storage bins with recessed door handles. For the first time, electrically operated side windows became available as an optional extra.
The exterior, too, saw little change, with the notable exception of the door handles. The external push buttons were eliminated in favour of hidden trigger levers on the inner sides of the handles.
In August 1970, the D series 911E was introduced. This was practically identical to the C series version with just a few detail changes, most of which were not obvious.
Exposed sections of the underbody received hot-dip zinc coating as additional rust protection, while the fuel pump was moved to the front crossmember to the rear of the car. The engine benefited from crankshaft oil-squirters and revised, sealed chain tensioner.
More obvious changes to the D series car were a new twist knob fitted to the centre of the glovebox and three-speed wipers with an intermittent setting.
The extra torque of the the 2.2-litre 911E makes it a more attractive used buy then earlier 2-litre cars for many people. In fact, some rate it higher than the more revvy 911S version.
It’s argued that a D series example with zinc coating is worth seeking out, but to be honest after all these years rust would have found its way into the bodyshell if it was going to. Note, too, that this was the last model that the troublesome hydropneumatic was fitted with.
The open Targa body-style continued with just minor improvements to the seals around the lift-out section.
The clutchless transmission system remained an option on the 911E, but was dropped from the 911S.
Compression ratio: 9.1:1
Maximum power: 155bhp at 6200rpm
Maximum torque: 191Nm at 4500rpm
Brakes: Front: 282mm discs; rear: 290mm discs
Suspension: Front: Boge self-levelling hydropneumatic struts; Rear: Trailing wishbones with telescopic dampers and transverse torsion bar
Wheels & tyres: Front: 15x6J with 185VR tyres. Rear: 15x6J with 185VR tyres
0-60mph: 7.5 sec
Top speed: 137mph