build and derivatives
Besides its prototype, dismantled in 1978 when Fuhrmann terminated the competition programme, Weissach built 31 934s, beginning with chassis number 930 970 0151. Today almost all of the cars are believed to exist, and some have been restored to 1976/7 condition. Porsche made another ten so-called ‘934.5s’ for US IMSA competition, but the authorities, fearing another Porsche walkover, initially ruled against turbocharging. These 934.5s, which had full width rather than 930 rear spoilers, wider tyres and mechanical fuel injection made over 600bhp: they found an outlet in SCCA events and provided Follmer’s winning mount in the 1976 Trans Am Championship. A few raced in Europe in Group 5 from 1977, and some teams converted them to full 935s.
and exhaust ports enlarged to 43.5mm and 36.5mm. Special pistons were used for greater durability at high crank speeds, but the connecting rods were stock, as was the 6.5:1 compression ratio. Like the production car, the 934 was fed by Bosch K Jetronic injection rather than the mechanical fuel injection used by Porsche hitherto in competition.
As with the rest of the car, the 934’s transmission was essentially the 930’s, whose specific four-speed gearbox, capable of transmitting 644Nm, was heavier duty than the five-speed 915 used on the 3.0 RSR and production 911s. Porsche offered standard ratios, plus two different ratio sets and final drive ratios, the limit of what the GT rules would allow. The 934 gearbox had its own oil cooler, a mechanical pump which circulated its oil through a cooling matrix mounted in the rear wing. Compared with the road-going
930, gear lever travel was considerably reduced and the precision of the shift enhanced by more solid mounting of the engine and gearbox to the shell. Porsche engines rarely broke, and when they did, the culprit more often than not was a missed gear change. Again the clutch was standard 930, albeit with a stronger diaphram spring and sintered metal plates. A limited-slip differential with an 80 per cent locking factor was standard.
The 934’s base price was DM 97,000, equivalent to $43,000 or £25,000 at the time. A few extras, such as additional sets of gear ratios and a cockpit-mounted boost adjuster, plus spares would add a few thousand Deutschemarks, but this still represented value for money. As one of its first buyers, US racer Al Holbert, who in the 1980s lead Porsche’s racing programme in America, remarked: “With everything you need for a hundred thousand marks it’s still cheap for what you get.”
As so much of the material was already proven, the development process was rapid. Design work in earnest had begun in May 1975, and by September Berger’s prototype was accruing test miles around the track at Weissach. There was further testing at Paul Ricard, then in January Manfred Schurti lapped the Nürburgring 15 seconds quicker than his best in the previous year’s 3.0 RSR. By early February 1976, a dozen of the 31 series 934s which Porsche would build during the season had already found takers.
Buyers were well established teams, most of which had raced Porsches previously. In Europe Kremer, Loos, Max Moritz, the Jolly Club and Alméras; in the US Vasek Polak and Al Holbert and in Australia Alan Hamilton. The 934s were driven by all the top Porsche racers, and to no one’s particular surprise the 934 was absolutely dominant in GT competition. Although Porsche never developed it further, it won the GT class at Le Mans in 1977, 1978 and 1980.
The 934’s most successful pilot in that first season was Toine Hezemans, who took seven wins and four second places in 20 races to win the GT Championship for Georg Loos. In the US George Follmer won the Trans Am Championship, and in
1978 Jacques Alméras won the European Hill Climb Championship. Always a privateer’s car and latterly boosted to 590bhp by some teams, the 934 continued to flourish at lower levels of competition until the early 1980s when Group 4 faded away.
However, compared with the beautifully balanced 3.0 RSR, the turbocharged 934 was a challenge even for the most skilled drivers. Hezemans remarked: “The 934 was brutal. It had almost 200hp more than the 3.0 RSR we were used to and you never knew where the boost was going to come in. It made it particularly difficult to drive.”
The engaging Al Holbert commented to Car
& Driver: “It always seems I am out of control in the damn thing. That’s the only way it goes fast.
It’s a small car with a small wing and small tyres, so you slide it into a turn, get it sideways and pointed in the direction you want to go, which lets you get on the power much earlier. It’s very responsive to brake and steering effort, just like the street cars. When I get into a 911 afterwards, it doesn’t feel that different.”
Another seasoned 911 exponent who recalled the 934 was Nick Faure, who shared Belgian Jean Blaton’s car at Le Mans in 1976. “The single-turbo Porsche were a handful. I took Jackie Ickx’s advice to commit the car to the corner then saw away with the steering wheel to scrub off speed while not lifting your right foot. I got the hang of it in the end, but it took some bottle!”
This 934, chassis number 930 670 0153 and object of our photography, was delivered in yellow to Jean Blaton at Le Mans, and Faure, a professional artist, painted and signwrote it for him in the paddock. The team was unlucky. Turbo technology was still new and Faure says that they had not understood that the car needed to idle for a minute or so to cool the turbocharger bearings before switching off. During the 24 hours they went through four turbo chargers. The time lost reduced them to unclassified at the finish. Blaton sold chassis 0153 to fellow Belgian Jean-pierre Gaban and in 1977-78 it achieved a couple of outright wins and second places at Spa, Nivelles and Zolder in the hands of Willy Braillard and Marc Duez. After 1979 the 934 was more or less retired in its original state. It joined the JFD collection in 2016 where with Le Mans Classic in prospect, it is very unlikely to remain a static exhibit.
“The 934 was designed specifically to provide previous RSR clients with a far more powerful entry for the 1976 season”