Having been postponed in 1975 due to a lack of manufacturer support, the FIA's Group 5 regulations were eventually introduced in 1976. For the first time, grand touring and prototype cars were given separate championships, the GT series being contested by crack Group 5 and less highly modified Group 4 machinery. Porsche were ready with a pair of new turbocharged models for each class, the 934 having been routinely available to customers wanting to contest Group 4, the incredible Group 5 935 being reserved strictly for the factory team.

Based on 1974's 2.2-litre Carrera RSR Turbo, the 935 initially weighed in at 880kg, a full 90kg under the class minimum. This allowed Porsche to strategically position ballast and attain a perfect 40/60 front/rear distribution. Using the RSR Turbo's Bilstein gas damper suspension, cockpit adjustable rear anti-roll bar and 917-derived four-pot caliper brakes, the 935's wheels were 10.5 and 15-inches wide at the front/rear respectively. They were shod with Dunlop tyres. A new engine and gearbox were installed, the 2.8-litre turbocharged motor designated Typ 930/72 featuring ultra exotic componentry throughout. Just about the only parts it shared with the production 930 were the standard crankcase and crankshaft, everything else having been specially developed. To participate in the 4-litre swept volume regulations, Porsche were limited to a displacement of 2856cc which they achieved thanks to a bore and stroke of 92.4 x 70.4mm. This equated to exactly 3999cc when taking into account the solitary KKK turbocharger. Adjustable from within the cockpit, turbo boost could be varied from 1.2 to 1.5 bar and permitted between 550 and 650bhp. Compression was set at 6.5:1, an uprated twin plug ignition fitted and titanium connecting rods and driveshafts used. Transmission was the 934 four-speed.

Group 5 regulations dictated cars only had to retain a vague similarity to the series production machines upon which they were based. Porsche exploited these rulings and kitted the 935 out with massive wheelarch extensions (most notably at the rear where prominent airboxes were housed) and a huge split-level rear wing that initially featured an air-to-air intercooler. The intercooler was eventually deemed illegal though and the FIA forced Porsche to exchange it with a water-to-air intercooler from the 934 mid-way through the season. Undoubtedly the 935's most distinctive feature was an all-new Flat Nose front end that did away with the traditional 911 look. Incorporating banks of seven lourves atop each front wing, the driving lights were moved to the front bumper and pioneered a look that later become an expensive option on 911 road cars. A more conventional front end was also developed in case the FIA threw the Flat Nose out. Manufactured almost entirely from glassfibre (apart from the steel roof), side and rear glass was substituted for Perspex while a stock windscreen was used at the front. The prototype 935, chassis 930 570 0002, was completed in December 1975 but never raced, the next two cars (001 R14 and 002 R15) going on to form the basis of Porsche's 1976 campaign.

Click here for the 935's 1976 and '77 World Manufacturers Championship Review