Porsche 928 History - pure comfort and horsepower
The Porsche 928 grand tourer was made by Porsche from 1978 model year to 1995 model year, during which time it was one of their most expensive offerings.
By the late 1960s, Porsche had changed significantly as a company, and executives including owner Ferry Porsche were toying with the idea of adding a luxury touring car to the line-up. Managing Director Ernst Fuhrmann was also pressuring Ferdinand to "greenlight" development of the new model in light of concerns that the current flagship at the time, the 911, was quickly reaching its maximum potential where it could soon no longer be improved upon. Slumping sales of the 911 seemed to confirm that the model was approaching the end of its economical life cycle. Fuhrmann envisioned the new range-topping model as being the best possible combination of a sports coupe and a luxury sedan, something well equipped and comfortable enough to be easily driven over long distances that also had the power, poise and handling prowess necessary to be driven like a sports car. This set it apart from the 911, which was a pure sports car.
Ordered by Ferry Porsche to come up with a production-feasible concept for his new model, Fuhrmann initiated a design study in 1971, eventually taking from the process the final specs for the 928. Several drivetrain layouts were considered during early development, including rear and mid-engined designs, but most were dismissed because of technical and/or legislative difficulties. Having the engine, transmission, catalytic converter(s) and exhaust all cramped into a small rear engine bay made emission and noise control more difficult, something Porsche was already facing problems with on the 911 and wanted to avoid. After deciding that the mid-engine layout didn't allow enough room in the passenger compartment, a front engine/rear wheel drive layout was chosen. Porsche also feared at the time that the U.S. government would ban the sale of rear-engined cars in response to the consumer outrage over the Chevrolet Corvair, started by Ralph Nader via his book "Unsafe at Any Speed".
Porsche engineers wanted a large-displacement motor to power the 928, and prototype units were built with a 5.0 L V8 producing close to 300 hp. Very early units used one four-barrel carburetor, which was eventually tossed in favour of Bosch's K-Jetronic fuel injection system. When increasing concern within the company over the pricing and availability of fuel during the oil crisis of the 1970s became an issue of contention, smaller engines were considered in the interest of fuel economy. Some managers began pushing for development of a 3.3 L 180 hp powerplant they had drawn up specs for, but company engineers balked at this suggestion. Both sides finally settled on a 4.5 L, SOHC 16-valve V8 producing 240 PS (219 hp in North America), which they considered to have an acceptable compromise of performance and fuel economy.
The finished car debuted at the 1977 Geneva Motor Show before going on sale later that year as a 1978 model. Although it won early acclaim for its comfort and power, sales were slow. Base prices were much higher than that of the previous range-topping model and its larger size and somewhat odd futuristic styling put off many purists who were more attracted to more compact 911.
Fuhrman's replacement, Peter Schutz, decided that the models should be sold side by side, feeling that the 911 still had potential in the company's line-up. Legislation against rear-engined vehicles also didn't materialize.
Although the 928 developed an avid fan following, it never sold in the numbers that Fuhrmann had originally predicted and was discontinued in 1995. The size of the market for expensive and extravagant grand tourers has increased since then, and the company is again looking to capture this market with the Porsche Panamera four-door GT.
The 928 featured a large, front-mounted and water-cooled V8 engine driving the rear wheels. Originally displacing 4.5 L and featuring a single overhead camshaft design, it produced 219 hp (163 kW/222 PS) for the North American market and 240 PS (176 kW/237 hp) in other markets. Porsche upgraded the engine from mechanical to electronic fuel injection in 1980 for US models, although power remained the same. This design marked a major change in direction for Porsche (started with the introduction of the 924 in 1976), whose cars had until then used only rear- or mid-mounted air-cooled flat engines with four or six cylinders.
Porsche utilized a transaxle in the 928 to help achieve 50/50 front/rear weight distribution, aiding the car's balance. Although it weighed more than the difficult to handle 911, its more neutral weight balance and higher power output gave it similar performance on the track. The 928 was regarded as the more relaxing car to drive at the time. It came with either a five-speed dog leg manual transmission, or a Mercedes-Benz-derived automatic transmission, originally with three speeds, with four speed from 1983 in North America and 1984 in other markets. More than half of production had the automatic transmission. Exact percentage of manual gearbox cars for entire production run is not known but its believed to be between 25 and 30%.
The 928 qualified as a 2+2, having two small seats in the rear. Both rear seats could be folded down to enlarge the luggage area, and both the front and rear seats had sun visors for occupants. The 928 was also the first vehicle in which the instrument binnacle moved with the adjustable steering wheel, a feature seen more recently on Nissan's 350Z sports car.
The 928 included several other innovations such as the "Weissach Axle", an early all-wheel steering system that provides passive rear-wheel steering in certain off-throttle cornering situations, and an unsleeved, silicon alloy engine block made of aluminium, which reduced weight and provided a highly durable cylinder bore. The concept of all-wheel steering was also adopted later on to several Japanese automobiles, including a Japanese-market version of the Toyota Celica, the Mitsubishi 3000GT VR-4 and the second generation Nissan 300ZX.
Porsche's design and development efforts paid off during the 1978 European Car of the Year competition where the 928 won against the BMW 7-series and the Ford Granada. The 928 is the only sports car so far to have won this competition, where the usual winners are mainstream hatchbacks and saloons from major European manufacturers. Proof of how advanced the 928 was compared to its contemporaries.
Porsche introduced a refreshed 928 S into the European market in 1980, although it was summer of 1982 and 1983 model year before the model reached North America. Externally, the S wore new front and rear spoilers and sported wider wheels and tires than the older variant, but the main change for the 928 S was under the hood, where a revised 4.7 L engine was used.
European versions debuted with 300 PS (221 kW/297 hp), and were upgraded to 310 PS (228 kW/306 hp) for the 1984 model year. From 1984 to 1986 ROW (Rest Of the World) S model was officially called S2 in UK. North American spec 1983 and 1984 S models used, among other differences, milder camshafts and additional emissions regulation equipment, and were limited to 239 hp (174 kW/242 PS) as a result.
As the faster S model was not available in the USA and Canada during the first three years of its existence, a "Competition Package" option was created to allow North American customers to have an S model lookalike with spoilers, 16" flat disc wheels, sport seats, sport springs and Bilstein shocks. Customers could specify paint and interior colors the same way as on a normal 928. The package was available in the 1981 and 1982 model years and was cancelled in 1983 when the S model became available for these markets. Many cars have had S features added by subsequent owners, making original "Competition Package" cars difficult to distinguish without checking option codes.
In 1982, two special models were available for different markets. 205 "Weissach Edition" cars were sold in North America. Unusual features were champagne gold metallic paint, matching brushed gold flat disc wheels, two-tone leather interior, a plaque containing the production number on the dash and the extremely collectible three-piece Porsche luggage set. It's believed these cars were not made with S spoilers even though these were available in USA during this time period as part of the "Competition Package." The "Weissach Edition" option was also available for the US market 911 in 1980 and 924 in 1981 model years.
140 special "50th Jubilee" 928 S models were available outside the USA and Canada to celebrate the company's 50 year existence as a car manufacturer. This model is also sometimes referred to as the "Ferry Porsche Edition" because his signature was embroidered into the front seats. It was painted meteor metallic and fitted with flat disc wheels, wine red leather and special striped fabric seat centers. Similar 911 and 924 specials were also made for ROW markets.
Porsche updated the North American 928 S for 1985, replacing the 4.7 L, SOHC engine with a new 5.0 L, DOHC unit sporting four valves per cylinder and producing 288 hp (215 kW/292 PS). Seats were also updated to a new style. These cars are sometimes unofficially called S3 to distinguish them from 16-valve S models. European models kept a 4.7 L engine, which was slightly more powerful, as standard; a little detuned 32-valve engine together with catalytic converters became an option in some European countries and Australia for 1986. That same year, revised suspension settings, larger brakes with 4-piston calipers and modified exhaust was installed on the 928 S, marking the final changes to old body style cars. ROW models received these changes at beginning of model year while North American cars got them only after close to 900 cars were made, starting from VIN 1000. North American version of this late 1986 model is sometimes referred as S3.5 or S3½ because of these changes. Name is little misleading as more than 2/3 of 1986 North American model production had these updates.
The 928 S4 variant debuted in the second half of 1986 as a 1987 model, an updated version of the 5.0 L V8 for all markets producing 320 PS (235 kW/316 hp), spotting a new single-disc clutch in manual gearbox cars, larger torque converter in automatics and fairly significant styling updates which gave the car a cleaner, sleeker look. S4 was much closer in being truly world car than previous models as only major differences between ROW and US models were instrumentation in either kilometers or miles, lighting, front and rear bumber shocks and availability without catalytic converter in many ROW markets. Australian market version was only one with different horsepower rating at 300 PS (221 kW/296 hp) due to preparation for possible low grade fuel. Even this was achieved without engine changes.
A "Club Sport" variant which was up to 100 Kg lighter became available to continental Europe and USA in 1988. An SE (sometimes called the S4 Sport), a sort of halfway point between a normally equipped S4 and the more race-oriented "Club Sport," became available to the UK. It's generally believed these Porsche Motorsport engined cars have more hp than the S4. They utilize parts which later became known as GT pistons, cams, engine ECU programs and a stronger, short geared manual gearbox. The automatic gearbox was not available.
At beginning of 1989 model year also Australian model received same 320 PS (235 kW/316 hp) setup as other markets. Porsche debuted the 928 GT in the spring of 1989 after dropping the slow selling CS and SE. In terms of equipment, the GT was most like the 928 SE, having more equipment than a Club Sport model but less than a 928 S4 to keep the weight down somewhat. It had the ZF 40% limited-slip differential as standard like the Club Sport and SE before it. Also like the CS and SE, the GT was only available with a manual gearbox. ROW 1989 CS and GT wheels had an RDK tire pressure monitoring system as standard. This was also optional for same year ROW S4. For 1990 model year Porsche made RDK and a 0-100% variable ratio limited-slip called PSD (Porsche SperrDifferential) standard in both GT and S4 models for all markets. This system is much like the one from the 959 and gives the vehicle even more grip. In 1990 the S4 was no longer available with a manual gearbox.
The S4 and GT variants were both cut at end of 1991 model year, making way for the final version of the 928. The 928 GTS came for sale in late 1991 as a 1992 model in Europe and in spring of 1992 as an early 1993 model in North America. Changed bodywork, larger front brakes and a new, more powerful 5.4 L, 350 PS (257 kW/345 hp) engine were the big advertised changes; what Porsche wasn't advertising was the price. Loaded GTS models could eclipse $100,000 USD in 1995, making them among the most expensive cars on the road at the time. This severely hampered sales despite the model's high competancy and long standard equipment list. Porsche discontinued the GTS model that year after shipping only 77 of them to the United States. Total worldwide production for all years was a little over 61,000 cars.
Second-hand models have largely fallen in value, the result of generally high maintenance costs due largely to spare parts that are expensive to manufacture. The earliest versions, however, especially those models with the Bosch K-Jetronic (CIS) injection system, have few electronic components and therefore can be repaired more easily provided spare parts can be found.
The GTS model has retained a high value however, and as of 2006 the price for all variants is apparently starting to creep upwards (Classic Motorsports, March, 2006 issue, p. 38). A great community dedicated to the 928 exists online even today, and the car has won a huge fan base. The 928 was such a powerful vehicle in its day that even models 25+ years old are able to outperform current sport/grand-touring models of various manufacture.
Also noteworthy is that there are several manufacturers of supercharger and turbo kits specifically for the 928. The stock engine for any year is capable of handling significant power increases without part failure. More owners have opted for supercharging their vehicles as the conversion is reasonably straight forward whereas the fitting of two turbo chargers on each of the exhaust manifolds has caused problems because of the lack of space.
Styling was the same from 1978 through 1979 and the body lacked both front and rear spoilers. From in North America) through 1986, front and rear spoilers were present on "S" models, rear spoilers were integrated into the hatch. From 1987 through 1995, the front spoiler is integrated into the nose and the rear spoiler became a separated wing rather than an integrated piece, and side skirts were added. The rear tail-light configuration was also different from previous versions. GTS model had wider rear fenders added to give more room for 9" wide wheels.
Another easily noticeable visual difference between versions is the style of the rims. Early 928s had 15" or 16" "phone dial"-style rims, while most 1980s 928s had 16" slotted "flat disc"s, CSs, SEs and 1989 GTs had 16" "Club Sport", later GTs had 16" "Design 90" style which were also option on same period S4s, the GTS used two variations of the 17" "Cup" rims.
Information detailing the evolution through the model years
The evolution of the 928 during its 18 years of production is quite subtle, and often confuses individuals interested in purchasing a 928. The tables below show the major differences, which were largely made to the nose, tail, interior, engine and rims.