Aug 16

Aug 16 Guide: Porsche 928

Porsche - Porsche 928 - 1970s Supercars - 1970s German Cars - 1980s Supercars - 1980s German Cars

Background

Although the 911 had only entered production in mid 1964, by the early 1970s, Porsche were concerned the model would soon be at the end of its development life. There were also murmurings that rear-engined cars would be outlawed from sale in the USA which compelled management to consider a replacement.

Porsche, now led by Ernst Fuhrmann, thought a larger, more conventional Gran Turismo would have a broader appeal than the quirky and sometimes difficult to handle 911.

Accordingly, in 1971, work began on a front-engined design study to potentially replace the 911.

The resultant 928 had a 2+2 seating layout, rear-wheel drive and a large displacement V8 cooled by water instead of air.

Such a machine would continue Porsche’s inexorable move upmarket.

The four cylinder 356 had started the trend, its Volkswagen components gradually being phased out in favour of better quality Porsche parts.

Then the 911 arrived: it had a bigger six cylinder engine and was a considerable step up in price.

The 928 would be a natural progression and establish Porsche as a builder of world class luxury GTs.

Unveiled at the Geneva Motor Show in March 1977, the 928 was initially sold alongside the 911 and entry level 924 (a four cylinder front-engined GT that started life as a collaboration between Porsche and Volkswagen). In 1975, Porsche had also introduced the 930: a turbocharged 911 that wasn’t even on the drawing board when the 928 got the green light.

Originally conceived as a limited production homologation special, demand for the 930 greatly exceeded the 400 units needed to go racing and Porsche made it a permanent fixture in their model line up. As a result, the firm ended up with two flagship models that inevitably took sales away from one another.

Chassis

The 928 was built on a hot-dip galvanised steel bodyshell with a 2500mm wheelbase. An 86-litre fuel tank was fitted underneath the trunk floor.

Front suspension was via a multi-link MacPherson strut arrangement.

At the back, Porsche fitted their brand new Weissach axle. An evolution of the semi-trailing arm configuration, the Weissach axle replaced the front pivot bushing of a trailing arm layout with a short link that allowed the suspension to adjust itself during cornering. The result was a dramatic reduction in lift-off oversteer and much improved stability.

Coil sprung shock absorbers were fitted at each corner along with anti-roll bars at either end.

Ventilated brake discs had a diameter of 282mm at the front and 289mm at the rear.

Wheel size depended upon which gearbox was specified. Manual cars rode on 16-inch diameter rims while 928s with the automatic option came with 15-inch wheels. Width of the Teledial alloys was 7-inches all round regardless of which transmission was used.

Power steering was fitted as standard.

Engine & Gearbox

In the engine bay was Porsche’s first production V8: the Type M28

Although the mid 1970s Oil Crisis had made Porsche consider a smaller engine for the 928, the lusty M28 was smooth, powerful and torquey. It also had great development potential.

The M28 was an all-alloy water-cooled motor with single overhead camshafts, two valves per cylinder and wet-sump lubrication.

Displacement was 4474cc thanks to a bore and stroke of 95mm and 78.9mm respectively.

Bosch K-Jetronic fuel-injection was employed along with a conservative 8.5:1 compression ratio.

European market engines came in two types: M28/01 if coupled to a manual gearbox or M28/02 for automatics. Peak output was 240bhp at 5500rpm and 257lb-ft at 3600rpm.

928s destined for the USA and Japan came with engine types M28/03 (manual) and M28/04 (automatic). As a result of an exhaust gas recirculation air pump and catalytic converter, output was downrated to 230bhp at 5250rpm and 254lb-ft at 3600rpm.

To optimise weight distribution, Porsche installed a transaxle that combined the gearbox, axle and differential as part of an integrated unit.

The standard manual gearbox was a five-speed unit while the optional automatic had three speeds.

Bodywork

Bodywork was styled by Wolfgang Mobius under the guidance of Anatole Lapine.

To improve weight distribution, the doors, front wings and bonnet were aluminium. The fully integrated bumpers were made from body coloured polyurethane elastic while pretty much everything else was steel.

The long hood was free of any ducts, vents or blisters. Instead, a large intake for the front radiator was discretely located at the base of the front apron.

The gently sloping nose was home to perhaps the car’s most unusual feature; a pair of distinctive Lamborghini Miura-style retractable headlights.

Visibility out of the large single piece glass windows was excellent. The softly curved cockpit featured a fastback tail with lift up hatch that gave access to the substantial luggage area. The rear seats could also be folded down should extra space be required.

Interior

Inside, Porsche fitted an adjustable instrument binnacle and steering wheel. Housed centrally in the binnacle were large read outs for road and engine speed, outboard of which were smaller combined dials for water temperature / fuel and oil pressure / battery amps. Mounted on either side of the binnacle were distinctive vertically stacked clusters of several key buttons along with the ignition.

The rest of the switchgear (ventilation controls, radio etc.) were located on the central console that adjoined the slim forward section of the transmission tunnel. This widened dramatically towards the back of the car and meant the rear seats were no more spacious than those in the 911.

Seats were upholstered with leather bolsters and fabric centres (either chequered Pascha or pinstripe). Door panels were trimmed to match.

Options

In addition to automatic transmission, options included a 40% locking differential, sports seats, leather upholstery, two-tone leather, contrast seat piping, a choice of patterns for the seat and door inserts, air-conditioning, Bilstein dampers, an electric sunroof, rubbing strips, tinted glass, rear seat belts and a passenger side mirror.

Weight / Performance

Euro market cars weighed in at 1450kg regardless of the transmission specified.

The manual variant had a top speed of 143mph compared to 140mph for the auto.

0-62mph times were 6.8 and 8 seconds respectively.

Primarily as a result of increased side impact protection, US and Japanese market cars were a little heavier: 1490kg for the manual and 1530kg for the automatic.

Start of Production

Production got underway in September 1977 for the 1978 model year.

The first right-hand drive 928s arrived in February 1978.

The model was acclaimed for its comfort, power and design; in 1978 it won European Car of the Year, the only sports car to have achieved this feat. However, sales were lower than expected and Porsche soon decided not to drop the 911.

That first year, 3830 examples of the 928 were produced. Of these, 2636 were Rest of World examples, 1129 were US spec. and 65 went to Japan.

1979 Model Year

For the 1979 model year (production of which began in August 1978), Porsche integrated the battery box as part of the body shell (it was previously mounted on the gearbox).

5437 cars were built split as follows: 3049 Rest of World, 2275 US and 113 Japan.

Only twice again would Porsche sell more than 5000 examples of the 928 in a twelve month period (during the 1983 and ‘84 model years when the S version became available in the US) but the figure achieved during the 1979 model year was never surpassed.

1980 Model Year

More changes were on the way for the 1980 model year (starting from August 1979).

Most notably, a new bespoilered 928 S with 4.7-litre 300bhp engine was introduced (covered separately). Both versions of the 928 now came with side-mounted indicators behind the front wheelarches.

Meanwhile, the existing 4.5-litre engine also came in for some attention.

European-spec. cars received a higher 10.0:1 compression ratio (up from 8.5:1). Although power was unchanged, these Type M28/09 (manual) and M28/10 (auto) engines had an improved torque rating of 279lb-ft at an unchanged 3600rpm (up from 257lb-ft).

Euro market variants also now came with 928 S brakes (thicker discs with redesigned calipers and larger pads) plus automatic gearboxes with four instead of three speeds.

US and Japanese-spec. 928s for the 1980 model year had Type M28/13 (manual) or M28/14 (auto) engines. Compression was upped to 9.0:1 and new Bosch L-Jetronic fuel-injection was utilised (as opposed to K-Jetronic). Power was up slightly (from 230bhp at 5250rpm to 232bhp at 5450rpm). The torque rating also improved (265lb-ft as opposed to 254lb-ft at an unchanged 3600rpm).

During the course of the 1980 model year, the gearbox fitted to all manual 928s was modified with a shorter torque tube and different rear subframe.

Production dropped from a high of 5437 units to 2977 although an additional 1456 examples of the S were also manufactured which took this total to a combined 4433. Of the 2977 examples of the 4.5-litre 928 built, 1182 were Rest of World examples, 1639 went to the US and 156 to Japan.

1981 Model Year

For the 1981 model year, Porsche offered customers in the USA an optional Competition Package. It included sports seats, Bilstein dampers, a three-spoke steering wheel plus the spoilers and wheels from the 928 S. Production began in August 1980 and ran until July 1981.

US-spec. 928s also got engines with new type numbers (M28/15 for manual or M28/16 for auto) but no major changes were actually made.

928 sales continued their downward trend for the 1981 model year with 2412 examples of the 4.5-litre car produced along with 1409 of the S version for a combined figure of 3821 units.

The 2412 figure for 4.5-litre 928 sales was split as follows: 647 Rest of World, 1658 US and 107 Japan.

1982 Model Year

The 1982 model year was the last for the 4.5-litre 928.

Porsche added a vibration damper to the torque tube and a reverse gear lock to the manual gearbox.

US derivatives now came with the same brake system fitted to Rest of World derivatives.

During its final twelve months in production, sales of the base 928 jumped from 2412 to 3208 units which, combined with 1409 928 S sales took the total production figure to 4660 units.

The figure of 2412 base 928s was split as follows: 447 Rest of World, 2651 US and 110 Japan.

928 Weissach Special Edition

The Weissach 928 special edition offered in the USA during the 1982 model year featured Champagne Metallic paint with either a monotone brown or a duo-tone brown and tan full leather interior. A three-piece set of luggage and a numbered plaque on the dash were included as well, along with the forged alloy wheels and spoilers from the 928 S.

205 were built.