Guide: Blown Logic - a Historical & Technical Appraisal of the Porsche 911 3.0 Turbo (930)
Background
The 2.7-litre Carrera RS introduced for model year 1973 was Porsche’s first 911-based homologation special and spawned a series of dominant racing variants that annihilated the opposition.
Less expected than its on-track success, the 2.7 RS also became a commercial hit. Porsche had only planned to build 500 units to qualify for the FIA’s Group 4 class. However, over 1500 were eventually sold which also enabled the model to go racing in Group 3 which had a 1000-car stipulation.
For 1976, the FIA made several changes to the existing racing categories. Production requirements for the Group 4 Grand Touring class were reduced from 500 units in twelve months to 400 units in 24-months.
The existing Group 5 class for three-litre Sports Prototypes became Group 6.
As for Group 5, that became a Special Production Car class for more heavily modified versions of machines that had already been homologated in Groups 1 through 4. Major changes were permitted so long as the standard bonnet, roof and door profile of the base car was retained. This led to Group 5 sometimes being referred to as a Silhouette formula.
With Groups 4 and 5 in mind, Porsche created their second 911-based homologation special: the turbocharged 930.
By this time, the firm was already experienced in the art of forced induction - between 1972 and 1973 they had successfully campaigned the 917/10 and 917/30 Group 7 cars which were followed by the experimental 2.2-litre Carrera RSR Turbos of 1974.
Like the 2.7 Carrera RS, the 930 proved another big seller. It was actually so popular that Porsche quickly decided to make the 911 Turbo a permanent fixture in their model line up. Just as importantly, the Group 4 934 and Group 5 935 racing cars were enormously successful and dominated their respective categories for almost a decade.
The first (engine-less) 930 mock-up (chassis 9113300157) was displayed at the Frankfurt Motor Show in October 1973. At this stage, the silver and white-striped prototype retained many 3.0 Carrera RS features to include the bumpers, fenders, wheels and seats.
A narrow-bodied 911 2.7 Carrera Turbo prototype was built in early 1974 (chassis 9115600042). Having served as a development car, it was refurbished and gifted to Ferry Porsche’s sister, Louise, on her 70th birthday in August 1974.
The more-or-less production-ready 930 was unveiled at Frankfurt in October 1974. At this stage it famously featured cross-drilled and ventilated discs from the legendary 917, but for production Porsche simply imported the contemporary 911 arrangement for reasons of longevity.
930 production started in February 1975 on the H-series platform. It was an immediate success and demand outstripped supply.
The 400 cars required by Group 4 had been produced by the end of 1975 and homologation was approved on December 6th. By this time, the 1976 model year I-series 911 Turbo was in production.
Chassis
930s were based around the contemporary 911’s standard steel bodyshell.
Steering was non-assisted and an 80-litre fuel tank was imported from the regular 911 and similarly mounted under the front lid.
Suspension was lifted from the 1974 model year 3.0 Carrera RS. Up front were MacPherson struts with lower wishbones, longitudinal torsion bars and anti-dive geometry. The back end used semi-trailing arms with anti-squat.
Bilstein shocks were fitted all round and along with an anti-roll bar at either end.
Dual circuit brakes ran separate systems for each axle. Discs and calipers were sourced from the 2.7-litre Carrera. Disc diameter was 282.5mm front and 290mm rear.
Forged light alloy wheels were supplied by Fuchs with 15 x 7-inch rims at the front and 15 x 8s at the back. These were normally shod with Dunlop or Pirelli tyres (205/50 and 225/50 respectively).
Compared to the 1975 model year 911 2.7 Carrera, track was 60mm wider at the front and 108mm wider at the rear.
Engine / Transmission
The 930’s air-cooled all-alloy Flat-6 motor was developed from the 1974 3.0 Carrera RSR power unit.
As usual, it came with dry-sump lubrication and single overhead cam two-valve heads.
Designated Type 930/50, the new motor featured forged alloy pistons with Nikasil barrels along with a lightweight aluminium crankcase.
Displacement was 2994cc thanks to a bore and stroke of 95mm and 70.4mm respectively with the former having been taken out by 5mm over the existing 2.7-litre engine.
A single KKK 3 LDZ turbo ran at 0.8 bar. The compression ratio was dropped to 6.5:1 in order to limit full boost compression to 11.7:1.
Fuel-injection was via Bosch’s familiar K-Jetronic system.
Peak output was 260bhp at 5500rpm and 253lb-ft at 4000rpm.
For comparison, the most potent normally aspirated 911 of the time (the 911 2.7 Carrera) pumped out 210bhp at 6300rpm / 188lb-ft at 5100rpm.
A new Type 930/30 aluminium-cased four-speed gearbox was installed as Porsche were concerned about stripping gears in the regular 915 ‘box. They deemed the level of torque so great that a five-speed unit was unnecessary.
Bodywork
The 930 was initially only available as a Coupe.
It most obviously differed from normally aspirated 911s by way of its dramatically flared wheelarches and some special new aero.
To keep the front end pinned, a matt black wraparound chin spoiler was installed.
Integrated with the engine cover was a Tea Tray rear spoiler from the 3.0 Carrera RS adapted to incorporate an additional cooling slot.
Down each flank were the 911’s fattest fenders yet. By the time production got fully underway, a satin black shark fin-style stone guard was added to protect the rear arches from road rash.
Satin black window frames were standard with traditional bright metal work a no-cost option.
Steel body panels were used throughout.
Although the 911 Turbo may have lacked the visual drama of a Ferrari Berlinetta Boxer or Lamborghini Countach, for many customers that was a large part of its appeal. Uniquely among its peers, the 930 packed a supercar punch in a relatively discrete package that was genuinely practical enough for prolonged everyday use.
Interior
The familiar 911 cockpit was equipped to a very high standard. Despite being a homologation special, the emphasis was on luxury.
930s came with half leather sports seats that featured new tartan fabric centres plus door panels trimmed to match.
A small diameter three-spoke steering wheel was upholstered in leather and extra sound insulation was fitted along with deep pile carpet.
An 8000rpm rev counter replaced the 7000rpm tach fitted to regular 911s. A boost gauge was not yet fitted to production cars. Off to the left of the rev counter were combined read outs for oil pressure / oil temperature and oil level / fuel. To the right was a 300kmh / 180mph speedo and a clock.
Standard equipment included electric windows, a four-speaker stereo with front fender-mounted electric antenna, a rear wiper, headlight washers and fog lights.
Options
Via the options list, customers could add a ZF limited-slip differential, rear fog lights, air-conditioning, an electric sunroof and a centre console.
Further customisation was available by special request - a perfect illustration of how Porsche’s customer racing department could create a VIP Spezial was chassis 9305700208 ordered by Austrian conductor, Herbert von Karajan.
A serial Porsche owner, von Karajan’s silver 930 (an H-series 1975 MY car from the first year of production) was equipped with a tuned engine, a roll cage, bright metal window frames and an elaborate Martini Turbo decal kit. It featured on the front cover of his best-selling Famous Overtures album and was later further uprated with Cibie spot lamps and racing-style seats.
Weight / Performance
The 930 weighed in at 1195kg, had a top speed of 154mph and could sprint from 0-62mph in 5.7 seconds.
It catapulted Porsche into elite performance car territory, but the 930 was considerably less expensive than most of its rivals.
1975 Model Year H-series
284 H-series 1975 model year 930s were built during the first months of production (February 1975 to August 1975). All were left-hand drive.
1976 Model Year I-series
1976 model year production began in September 1975.
Boost pressure was increased from 0.8 to 1.0 bar and the turbo was enhanced with a by-pass valve to bring the power in more progressively.
Pirelli’s new low profile P7 tyres were now fitted as standard.
The rear spoiler’s supplementary cooling slot was made much larger.
Also noteworthy was a new six-year anti-corrosion warranty that far-exceeded the guarantee given by any other high performance manufacturer at the time.
There were changes to the options list too: 16-inch diameter wheels became available (with a 4.222 final drive ratio) as did right-hand drive, a full leather interior and a cool Turbo-branded decal kit.
USA Version
North American customers were supplied with a US-legal 930 for the first time during the 1976 model year. These cars featured a revised Type 930/51 engine with additional emissions equipment that cost 15bhp. Peak power was now 245bhp at an unchanged 5500rpm.
Like other US-bound 911s of the era, the 930 (branded in the US as the Turbo Carrera) typically came with tailored sugar scoop headlights, extended amber front signals, red instead of amber rear signals and beefier rear bumperettes.
1977 Model Year J-series
For the 1977 model year J-series (production of which began in September 1976), Porsche introduced further updates.
A Hydrovac brake servo was installed on left-hand drive 930s to allow easier depression of the brake pedal.
Thicker 20mm anti-roll bars were fitted (up from 18mm).
16-inch Fuchs alloys and centre console became standard.
A boost gauge was added (within the tach), twin fuel pumps were fitted, the synchromesh on first and second gear was revised and the differential assembly strengthened.
The engine type number was changed from 930/50 to 930/52 and, in the case of US-market cars, from 930/51 to 930/53.
An optional Martini stripe kit was also introduced. It came after a unique ‘Martini Turbo’ was produced for the British Motor Show in October 1976. This show car also had special Fuhrmann orthopaedic seats trimmed in Martini colours. These Fuhrmann seats became an expensive but rarely seen option.
End of Production
The 1977 model year 930s were the last 3-litre cars built.
For the 1978 model year, an uprated 3.3-litre engine was introduced.
By the time production ended in August 1977, a total of 2880 three-litre 930s had been completed.
1623 of these were the 260bhp variants and the remaining 1257 were 245bhp US-bound derivatives.
Production tallies are as follows:
1975 model year H-series, Type 930/50 engine, 284 examples built, VIN range 9305700001 to 0284
1976 model year I-series, Type 930/50 engine, 644 examples built, VIN range 9306700001 to 0644
1976 model year I-series USA version, Type 930/51 engine, 530 examples built, VIN range 9306800001 to 0530
1977 model year J-series, Type 930/52 engine, 695 examples built, VIN range 9307700001 to 0695
1977 model year J-series USA version, Type 930/53 engine, 727 examples built, VIN range 9307800001 to 0727
Competition History
The 400 cars required for homologation had been produced by the end of 1975 and the 930 was approved for Group 4 / 5 on December 6th.
For the first time at World Championship level, 1976 saw production-based GT cars and purpose-built Sports Prototypes contest separate series. Porsche ran the Group 6 936 for what was dubbed the World Championship for Sports cars. The factory also ran works 935s in the production-based World Championship for Makes where cars from Groups 5 through 1 were permitted.
Porsche kept the 935 for works use in 1976 and won four out of seven World Championship events (the 6 Hour races at Mugello, Vallelunga, Watkins Glen and Dijon). Three wins went to the 3.5-litre BMW E9 CSL which meant Porsche took championship honours. Porsche also won Group 5 at the Le Mans 24 Hours with a fourth place finish overall.
Customer 935s were supplied for 1977 onwards and the BMW challenge for outright honours faded away as it looked to dominate the under 2-litre class Group 5 class with the E21 320. From this point, if the factory Porsche team didn’t win on its increasingly infrequent outings, a privateer car was normally able to pick up the win.
The 935 subsequently dominated all championships organised to Group 5 regulations: the World Sportscar Championship, IMSA, Germany’s domestic Deutsche Rennsport Meisterschaft, Trans-Am and of course, at Le Mans.
It was a similar story with the 934 although Porsche supplied these cars exclusively to customers and did not contest Group 4 in an official capacity. From 1976 until the end of that decade, the 934 out-scored any of its rivals in terms of major class wins by a quite enormous margin. Group 4 honours in all the aforementioned championships similarly fell the 934s way.
Text copyright: Supercar Nostalgia
Photo copyright: Porsche - https://www.porsche.com
