Fifty years separate these very special 911s, yet their origins could not have been more different. The 911R was an experimental lightweight that never advanced beyond the prototype stage, and for decades was almost forgotten. Then, as interest in Porsche history widened, the importance of the 911R was recognised to the point where it has become perhaps the most valuable of the early air-cooled cars; Porsche rarely misses an opportunity to build an anniversary model, but with the 991 R it pulled out all the stops to create as near a likeness to that original R as modern production would allow – a brilliant contemporary yet traditionally analogue 911.
To appreciate this 911, it is necessary to understand Porsche’s interest in saving weight as a means of gaining performance, which pre-dated Colin Chapman’s famous (and occasionally fatal) “add lightness” dictum by a decade. Competition and motor racing had always been the company’s shop window – it entered cars at Le Mans in 1951, barely a year after manufacture had begun in Zuffenhausen, and for 20 years Porsche built a series of lightened sports cars for the road, but really intended for the track, such as the Carrera 904 GTS.
From the outset, the power and agility of the 911 made it an obvious competition car, and in 1966 Porsche released the 911S, which with 160bhp per litre had one of highest power-to-weight production car ratios in the world. But for competitive racing, at 1,080 kilograms it was heavy: Vic Elford’s carefully tuned 180hp 911T took the 1967 Monte Carlo Rally, but weighed only 20 kilograms less than the standard car. For new technical director Ferdinand Piëch, structural weight counted almost as much as power. Where previously Porsche had relied on experience and instinct, Piëch now brought calculation and analysis: applied to a 911 by his experimental department, the 820 kilogram, 210hp 911R was the result. A rigorous diet typical of Piëch, he succeeded ultimately in saving 250 kilograms by measuring every component. A specific shell using thinner gauge steel, aluminium doors and bonnet, glass fibre front and rear bumpers, and finally plexi glass windows (except for the windscreen) brought the weight of the four prototypes down to 820 kilograms.
Nothing was overlooked: bulkheads and brackets were drilled, hinges simplified and cockpit equipment was reduced to three instruments mounted on a glass fibre dash and two state-of-the-art Scheel bucket seats. The doors had leather straps to pull them shut and small ‘T’ handles to operate to the simple latch, which looked suspiciously like something from a kitchen cabinet. Crude louvres in the front and rear quarterlights were intended to allow ventilation. Under the piano-hinged rear lid, the flat six was essentially the race-proved Carrera Six (906) engine using the same partially transistorised ignition and two sparkplugs per cylinder. A 10.3:1 compression ratio meant peak torque at a heady 6,100rpm and maximum power of 210bhp at 8,000rpm.
The R used the standard five-speed gearbox, but inherited the Carrera Six’s driveshafts and limited-slip differential. The oil tank was in aluminium and mounted ahead of the rear axle, endowing the R with its characteristic filler cap just beside the passenger door. With a power to weight ratio of around 260bhp/tonne, the 911R made an auspicious start on the track with a third place at Mugello (Elford/van Lennep) behind a Porsche 910 and a Ford GT40 and was quite untouchable in the 2.0-litre category, though unofficially, as it could run with prototype status only. Soon after came the famous victory in the 84- hour Marathon de la Route, with an R using the Sportomatic gearbox. This high-profile success enabled Piëch to get approval to build a further 20 cars. Their bodies were made by Karl Bauer (who also built the attractive BMW 2002 Cabrio) using normal gauge steel panels, but otherwise were of the same construction as the prototypes. In full rally trim the 911Rs weighed about 860 kilograms.
The intention as ever with Porsche was for the factory to race some of the cars, while a handful of privileged clients would campaign the others. Racing manager Huschke von Hanstein was keen to get the R homologated as a GT car: this would have the advantage of expanding Porsche’s racing activity beyond the saloon category, where the 911’s domination (and the fact that it was hardly a saloon anyway) was beginning to cause resentment among other manufacturers. Von Hanstein argued that as the shell for the R cost much the same as for the 911L, the venture would be profitable, but he and Piëch were overruled by management, which refused the potentially fruitless task of finding takers for the minimum 500 units required by FIA rules. This left the 911R as something of a competition orphan. It did make several more successful appearances – third overall again at Mugello in 1968, and coming out on top in the hands of Gérard Larrousse at the 1969 Tour Auto.