Review: Porsche 928 (1978-95)

Review: Porsche Mk.I 928 (1978-85)

Overview

Released in Australia in February 1978, the Porsche 928 was a two-plus-two coupe. Manufactured in Stuttgart, Germany, the rear-wheel drive 928 was initially available with a 4.5-litre V8 petrol engine that was mated to either a five-speed manual or three-speed automatic transmission. In June 1980, the 928 S was released with a 4.7-litre V8 petrol engine (see table below).

Engines

The 4.5-litre V8 petrol engines had an aluminium-silicon engine block, an alloy cylinder head, Bosch K-Jetronic fuel injection, a single overhead camshaft (per cylinder bank, belt-driven), two valves per cylinder, self-adjusting hydraulic valve lifters, water cooling and a compression ratio of 8.5:1. From 1980, however, premium petrol was required as the compression ratio was increased to 10.0:1.

Compared to the 4.5-litre unit, the 4.7-litre V8 engine had the same block but increased displacement due to its longer bore (increased from 95 to 97 mm). At the time of its release in 1980, its compression ratio of 10.0:1 was the same as the 4.5-litre engine though its camshaft profile was also revised. From 1984, however, the engine had Bosch LH-Jetronic fuel injection and the compression ratio was increased to 10.4:1.

Transmission

The 928 had a rear transaxle whereby the transmission was positioned in front of the rear axle for better weight distribution. Initially, transmission options consisted of a five-speed manual transmission with a hydraulically actuated twin-disc clutch and synchromesh on all five forward gears or a three-speed automatic transmission supplied by Mercedes-Benz. From 1984, the 928 S was available with a four-speed automatic transmission (also supplied by Mercedes-Benz).

In 1985, a new manual transmission was introduced with Borg Warner synchronizers.

Body

Styled by Wolfgang Möbius, the 928 was 4447 mm long, 1836 mm wide, 1313 mm tall and had a 2500 mm long wheelbase; the drag coefficient was 0.39 Cd. Kerb weight for the 928 was 1500 kg, in part achieved through the use of aluminium for the wheels, doors, bonnet, front fenders, front suspension members, rear suspension links and carrier, and the housings of the engine, clutch and transaxle. Furthermore, the 928 had a galvanised steel body whereby the steel was coated in zinc and an additional layer of lacquer.

Suspension and steering

The 928 had double wishbone front suspension and independent rear suspension with upper and lower diagonal control arms. Known as the Weissach axle, the rear suspension also had a compound pivot in each trailing member to provide toe-in during deceleration, thereby overcoming lift-off oversteer. Furthermore, the 928 had power assisted rack-and-pinion steering.

Safety equipment

From 1978 to 1985, neither the 928 nor 928 S were fitted with airbags or ABS as standard. ABS was available as an option, however, for the 928 S from 1984.

Features: 928

Standard features for the 928 included 15-inch alloy wheels with 215/60 7×15 Pirelli P6 tyres, a four speaker sound system with AM/FM radio and cassette player, air conditioning, cloth seats, cruise control, folding rear seats, central locking, power windows, a power adjustable and heated driver’s side mirror, a height adjustable steering wheel and instrument cluster, an illuminated vanity mirror and tinted windows.

Optional features included 16-inch alloy wheels with 225/50 VR16 tyres, power adjustable seats, leather trim, power adjustable passenger-side mirror, a power sunroof, power antenna and anti-theft system.

Features: 928 S

Compared to the 928, standard features for the 928 S were extended to include 16-inch alloy wheels with 225/50 7×16 Pirelli P7 tyres, climate control air conditioning, power adjustable front seats and power adjustable and heated mirrors for both driver and passenger sides.

Visually, the 928 S could be identified by its unique alloy wheel design, front air dam (with two rectangular slots for brake cooling), side rub strips and polyurethane rear spoiler which lowered the drag coefficient to 0.38 Cd.

From 1985, the 928 S featured more supportive front seats with additional power adjustment and lower seat rails; the radio antenna was also positioned in windshield.

Review: Porsche Mk.II 928 (1986-95)

Overview

From 1986, the 928 S was powered by a 5.0-litre V8 petrol engine which was designed to run on unleaded petrol. For 1987, the 928 S was replaced by the 928 S4 and single-plate clutch manual transmissions were introduced.

In 1989, the range was revised as the 928 S4 was solely available with an automatic transmission and the 928 GT was introduced. Available solely with a manual transmission, the 928 GT had a stronger emphasis on performance. From 1992, the 928 GTS replaced both the S4 and GT variants.

Compared to its 4.7-litre predecessor, the 5.0-litre V8 had a longer bore (100.0 mm, previously 97.0 mm), double overhead camshafts and Bosch LH-Jetronic fuel injection and electronic ignition. A new induction system was introduced for the 928 S4 in 1987, while the 928 GT had a further revised intake and different camshaft profile. For the 928 GTS, the engine’s stroke was extended to 85.9 mm (previously 78.9 mm) and the insulated intake tubes were replaced by moulded plastic tubes.

Safety equipment

From 1986, the 928 was fitted with ABS as standard.

Although airbags were available in international markets from 1990, a driver’s airbag was only fitted as standard for the 928 GTS from 1993.

Features: 928 S4

Relative to the 928 S, the 928 S4 was further equipped with leather seats and an alarm system. Compared to the 928 S, the 928 S4 could be identified by its new front bumper with holes for brake ventilation, new H4 headlights, updated fog lights, cooling flaps in front of the radiator to reduce drag and restyled tail-lights. Other changes included:

• underbody paneling to reduce aerodynamic drag (down to 0.34 Cd);
• the shift program for automatic transmissions was modified for second gear starts, though hard acceleration starts remained in first gear;
• upgraded brakes;
• wider eight-inch rear wheels (previously seven-inch) with 225/50 16 front and 245/45 16 rear tyres; and,
• a new air conditioning system

Features: 928 GT

Compared to the 928 S4, the 928 GT could be identified by its ClubSport alloy wheels, rolled fender lips, dual rear exhaust outlets and rear GT logo; the cooling flaps in front of the radiator were also discontinued. Befitting its status as a sports model, the five-speed manual transmission had shorter ratios, 17 mm rear wheel spacers and 225/50 8×16 front tyres and 245/45 9×16 rear tyres.

Inside, the 928 GT had a short-throw gearshift lever and the door seals were improved to prevent water ingress. Standard features, however, were largely unchanged.

Features: 928 GTS

Compared to the S4 and GT, the 928 GTS could be identified by its continuous red reflector between the rear brake lights, aero style door mirror shape, body-coloured rear wing.

In addition to its 5.4-litre engine, the 928 GTS had a more robust manual transmission which had a differential-driven oil pump and front-mounted cooler. The 928 GTS was also fitted with 322 mm front and 299 mm rear disc brakes, with upgraded Brembo calipers for the front discs.

Distinguishing standard features for the 928 GTS included 17-inch alloy wheels with 7.5Jx17 225/45 ZR17 front and 9Jx17 255/40ZR 17 rear tyres, a 160 watt sound system with ten speakers and a six channel amplifier, driver memory settings (for the seat and door mirrors) and a power sunroof with wind deflector.

Related links

• Wikipedia.org: Porsche 928