A GT for the American market
Designed in the early 1970s as the successor to the 911, the Porsche 928 is the perfect counterpart to the 911, both in terms of technology and design.
Unlike the small 924, that was developed in parallel with the Volkswagen Group, the future 928 was to be a 100% Porsche production. The idea was to design a 911 model that would be improved in all respects, with innovative technology and sports car performance, while offering a high level of comfort and safety.
The flowing and balanced silhouette of the 928 is surprisingly round and understated. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche
A futuristic design
The first studies for the future 928 (codenamed EA 425) were carried out during the summer of 1970 under the direction of Helmut Bott, head of Porsche's development department. On 21 October 1971, the specifications were drawn up and the project was handed over to the new Porsche Research & Development Centre in Weissach. Chassis engineer Wolfhelm Gorissen was put in charge, assisted by Wolfgang Eyb and Helmut Flegl. The objective was to start production at the end of 1975.
The first aerodynamic wind tunnel tests were conducted in February 1972 under the guidance of designer Anatole Lapine, assisted by Wolfgang Möbius, who succeeded in achieving an exceptional Cx of 0.39. Development and testing of the new V8 engine began in January 1973 and the first prototype was operational in April 1974. After a press preview on the Côte d'Azur in February 1977, the Porsche 928 was officially unveiled to the public the following March at the Geneva Motor Show. From the outset, this new Porsche seduced or disturbed the majority of those who discovered it, but above all amazed them. Its body, with a sloping bonnet at the front and a rounded silhouette at the back, gave it the appearance of a flying saucer with a purely functional aesthetic. The trade press was convinced and awarded it the prestigious title of "European Car of the Year" for 1978.
The headlights, which are electrically retractable, are flush with the hood when not in use. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche
The self-supporting body is made of galvanized sheet steel, with some elements such as the doors, engine covers and wings made of aluminum. The 928 features an engine that is placed longitudinally at the front, while the gearbox and axle are attached at the rear for better weight distribution. This system, called "Transaxle", had already been studied by Ferdinand Porsche for a Mercedes racing car before the war. Under the bonnet is an extremely compact 4.5-liter V8 engine, made of aluminum and water-cooled, a choice made to specially attract American customers.
A rigid tube enclosing the transmission connects the engine to the gearbox, located in front of the rear axle. The rear axle is a new "Weissach" type and contributes significantly to the 928's outstanding driving characteristics thanks to its double wishbone design. The transmission is a 5-speed manual, but a 3-speed automatic from Daimler-Benz is also available as an option, as is a ZF self-locking differential from the 911. Dual hydraulic braking is provided by four ventilated discs.
For the design of the 928, the Porsche stylist Tony Lapine was inspired by the concept car Chevrolet Corvair Testudo concept car created by Bertone ten years earlier. © IXO Collections SAS - Tous droits réservés. Crédits photo © Porsche
From 1979, the 928 was available in an S-version which distinguished itself externally by the addition of a front and rear spoiler. The displacement of the V8 engine was increased to 4664 cm3, that allowed the power to reach 300 hp at 5900 rpm. In 1983, the S2 version gained 10 more hp and three years later, the S4 version saw the engine displacement increase to 4,957 cc with a power output of 320 hp at 6,000 rpm.
The same engine is found in the 1989 GT version where it develops 330 hp at 6,200 rpm. A final GTS evolution was produced in 1991, with a new 5,397cc V8 delivering 350 bhp at 5,700 rpm, that allowed a top speed of 275 km/h. Between 1977 and 1995, 61,054 Porsche 928s were built in all versions. The 928 version (1977-1982) totals 17,710 units, the S, S2 and S4 versions (1979-1991) 39,009 units and the GT and GTS versions (1989-1995) 4,335 units.
Porsche 928 (1977) technical data
• Moteur : Type M28/01, 8-cylinder V-shaped at 90°, longitudinal front
• Displacement: 4,474 cm3
• Bore x stroke: 95 mm x 78.8 mm
• Power: 240 hp at 5,250 rpm
• Fuel supply: Bosch K-Jetronic mechanical injection
• Ignition: Bosh electronics
• Distribution: 2 overhead camshafts per bench, 2 valves per cylinder
• Transmission: Type G28/03, rear wheels, 5 gears + M.A.
• Tires: 225/50 VR 16 (front and rear)
• Brakes: ventilated discs (front and rear)
• Length: 444.7 cm
• Width: 183.6 cm
• Height: 128.2 cm
• Wheelbase: 250 cm
• Front track: 155.2 cm
• Rear track: 152.9 cm
• Weight (empty): 1,450 kg
• Maximum speed: 230 km/h
A reliable range
Between 1988 and 1989, Porsche launched the 928 S4 CS (Club Sport) in a limited series of 19 cars, for very wealthy customers. This exclusive model was designed in the spirit of the 911 Carrera Club Sport, produced in 340 copies the previous year. The 928 CS was approximately 130 kg lighter and equipped with the same engine as the S4: a 5-litre V8 with 320 hp at 6,000 rpm combined with a 5-speed manual transmission. This allowed for a top speed of 271 km/h. After two prototypes presented in 1987, five pre-series cars were produced and offered to the Porsche factory drivers of the time: Derek Bell, Hans-Joachim Stuck, Bob Wolleck, Jacky Ickx and Jochen Mass. Next step was the assembly of 19 production cars: 12 in 1988 and 7 in 1989.