The Porsche 928
It was hard to criticise in such a strong fashion the Porsche 924, progeny of a marque I adore, in the road test on page 553. Thank goodness then for the opportunity to redress the balance for Porsche, with a review of their latest departure from Dr. Ferdinand’s norm, the new 928, a supercar which has left me as ecstatic as the 924 left me depressed.
I have heard it said in quarters which ought to be more knowledgeable that the 2 plus 2 928 is basically an enlarged 924. Nothing could be further from the truth. The only things the two have in common are water-cooled, front-mounted engines connected to rear transaxles by torque tubes. Not even the doors are common, though they might appear so: those of the 928 arc larger and made from aluminium, as arc the bonnet and the bolt on front wings. Indeed, plans for the 928 were formulated before Audi-NSC commissioned the 924, so the latter borrowed layout ideas from the former.
This flattened, rounded bullet of a car is full of innovatory design features, all functional, none gimmicky. It is powered by a totally new, 90 degree V8 of 4,474 c.c. capacity which, in spite of its similar size and configuration, has absolutely no connection with the Mercedes-Benz. 4-1/2-litre V8, as some European “scoop” type magazines would have had us believe before the car’s announcement. Their spies were right in spotting a level of collaboration with Daimler-Benz, however, for a Mercedes three-speed automatic gearbox is offered as an alternative to Porsche’s five-speed manual gearbox.
Porsche’s decision to build this big, new sports car was taken during the energy crisis, a calculated gamble that the world situation would improve and demand for expensive luxury sports cars continue, particularly sports cars incorporating their philosophy that “a sports car is an automobile with above average characteristics that sets up standards not only in the area of performance but also in that of safety, comfort and long-life economy.” They also foresaw that future widely differing regulations would put rear-engined cars like the 911-series at a disadvantage; that a conventional car would meet such astringencies more easily, but at the same time some of the advantages of the rear and mid-engined cars should be maintained, particularly traction. Hence the transaxle system for good weight distribution.
The design of the 928 has to be seen in the flesh to appreciate its startling appearance; photographic flattening and miniaturisation do nothing for it at all. The sheer size and bulk of this rounded, fat-tyred missile make it quite stunningly aggressive. Yet it has no fancy styling gimmicks as such, except perhaps for the alloy wheels, which at the same time are harmonious and futuristic enough to help maintain the deliberate datelessness of this long-life, functional shape. Deformable, strut-mounted polyurethane bumpers at the front and rear retain their shape in minor impacts and have a layer of special elastic, main body-matching, paint. The main sections of the unitised body are made from galvanised steel. A roll-over bar is integrated with the structure. Headlamps fold flat in the blunted nose, uncovered eyes which point skywards when switched off, to be tilted forwards electrically when illuminated, in which position the driver can adjust them from his seat. The deformable front bumper houses spot-lamps which double up for daylight flashing, and fog lamps.
As installed, the new all-aluminium V8 engine looks almost like a flat-8 because of the angles of the valve gear and cam-covers. Each cylinder head carries one overhead camshaft operated by tooth belt. Hydraulic tappets are used to cut down noise and maintenance. The aluminium pistons have a thin coating of steel on their running surfaces to resist wear and the cylinder liners are made from a specially treated aluminium. The crankshaft is forged steel and the connecting rods sintered. Unlike the flat-6 911 series, the 928 has a wet sump, for which oil changes are recommended only once every 12,500 miles.
Porsche have stuck to Bosch’s mechanical K-Jetronic fuel injection system for this V8, supplied with 91-octane fuel (the compression ratio is 8.5 to 1) from the 18.9.gallon synthetic fuel tank via twin high-pressure pumps. Contactless ignition is fitted. This beautifully engineered engine, which has a bore of 95 mm. and a short stroke of only 78.9 mm. produces 240 b.h.p. DIN at 5,255 r.p.m. and 268 ft.lb. torque at 3,600 r.p.m. It pulls a kerb-weight of 28.5 cwt.
Drive is transmitted via a twin dry-plate clutch at the engine end, pedal operation being assisted by a helper spring in the fashion of the latest 911s. The driveshaft is carried through the torque tube in two sealed bearings to the five-speed gearbox, which is mounted at the front of the transaxle, unlike the 924’s four-speed gearbox, which is behind the differential. The battery is rigidly mounted to the rear of the transaxle for weight distribution. The fifth gear is direct and a high axle ratio of 2.75 to 1 is used.
The 928’s front suspension is conventional in that it has double cast aluminium wishbones, coil springs, telescopic dampers and an anti-roll bar. Anti-dive characteristics are built in along with negative scrub geometry. But at the rear is a novel suspension design called the Weissach Axle, after the Porsche engineering centre. In essence this consists of lower diagonal and upper transverse trailing arms, coil spring/damper units and an anti-roll bar. Where it is so clever is in compensating for the wheels’ natural tendency to attempt to toe-out, particularly from torque reaction during deceleration in a corner, which can have a disturbing rear end steering effect, ultimately with loss of control. The lower diagonal trailing arms are designed to have the opposite to this undesirable effect; the tendency is towards toe-in, though in practice it means that the wheels actually stay in the position they are meant to be. This system also compensates for flexibility in suspension bushes. Anti-squat and anti-dive measures are incorporated too.
Four servo-assisted ventilated disc brakes with diagonal dual circuits and floating calipers are backed up by a mechanical, drum-type handbrake on the rear wheels. A little bit of patriotism for we British here: the 928’s seamless, cupronickel brake pipes, guaranteed against corrosion for the vehicle’s life, were developed and are manufactured and supplied by Yorkshire Imperial Metals Ltd., Leeds.
This is the first Porsche to feature power steering, the 17.75 to 1 rack-and-pinion system being assisted by ZF, a standard fitment.
I had been bitterly disappointed to have to miss the Press introduction of the 928 in the South of France in early March, but was able to make amends when Mercedes invited me to Stuttgart to try their new C 123 coupe, described on page 516. Mercedes kindly allowed me to move on to Zuffenhausen when their function had ended, where Porsche Press Officer Gunther Hornig found me a 928 to play with for the best part of a day. At this time 928s were few and far between: only eleven pre-production prototypes had been built for the Press launch, most of those had been commandeered for further testing at Weissach and Herr Hornig was left with two on his Press fleet, upon which demands were being put by journalists from all over the world. Production was not due to start until this month (May), on a new line installed in the main Zuffenhausen Porsche plant.
The first impression of the 928 was its size. At just over 6ft. wide it is slightly wider than an Aston Martin. It is 4.3 ft. high and 14.6 ft. long. It seems to be all wings and wheels, the main body is tumbling out into vast wheel arches to accommodate the 7j X 16 in. wheels shod with 225/50 VR 16 Pirelli P7 tyres. Yet the cockpit feels compact, almost small. I spent a good five minutes learning about all the controls and gadgetry from young Peter Jann, the helpful Porsche Press fleet controller, who came along with me for the ride. The previous weekend Peter had spent a marvellous time using this aptly silver 928 as course car at a Nurburgring race meeting. Interesting features include an instrument console which adjusts in height in unison with the steering column, so that its clarity is unaffected; the door arm-rests which adjust for angle; a driver’s seat which seems to have infinite adjustment in all directions (electrical operation is optional); adjustable pedals, foot-rest and gear-lever: a vacuum locking system; a metering pump with timing relay which jets a special cleaning fluid on to the windscreen, separately from the main washer system; the Tempostat cruising speed control device; the Bosch-Porsche four-speaker stereo radio-cassette system with automatic station tracer; a novel central warning system; electric windows; the cockpit headlamp adjustment; an electrically adjustable exterior mirror. There seemed to be so many things, a totally comprehensive package. The tailgate, which automatically de-clutches the parallel arm rear screen wiper when lifted, covers a conveniently large boot area, beneath which lies a space-saver spare wheel and tyre, first aid kit, warning triangle, electric tyre pump and tools. The rear seats, split by a broad arm rest/locker, fold down separately to enlarge the luggage space; a hardboard extension can be pulled out to fill the gap. There is more room in the deep, curvaceous rear seats, which have unusual segmented upholstery, than in the 924, but they remain a tightish squeeze for adults.
I felt lost as I sat in that driver’s seat for the first time, aware of a broad expanse of disappearing bonnet and invisible wheel arches which extended far beyond the point intimated by the deceptive window lines. The cold engine started promptly with a muted rumble alien to Porsche. First is down to the left in the pattern Porsche dispensed with years ago on the 911 series; this gear, reverse and second and third were hard to find in the cold gearbox. Once out of the Zuffenhausen gates and on the main road to the autobahn the deceptive width and my judgement seemed to click together, the mixing medium being power steering which is so astonishingly good as to be sensational. In the past I have praised Mercedes power steering as the best in the world. No longer. This Porsche ZF system is is positive, superbly weighted, precise. It is of variable ratio, but one isn’t aware of that. I had to check with , technical details to convince myself that it really was power assisted.
We headed off the busy Stuttgart-Frankfurt autobahn on to a new and quiet section of autobahn to Schwabsich Hall on our way to the twisting country route where I had tried the Mercedes coupes the previous day. This Porsche soared itself dreamly up to over 230 k.p.h. ( 143 m.p.h.), the maximum claimed by the factory, without the seemingly instant “whoosh” which the turbo does to higher figures. I was a little bit shocked to find a hard-trier in a 450SL just about holding on to me with the 928 flat out. Until we came to the first real curve, when the Porsche remained “flat” and unruffled, while the Mercedes fell back before trying again on the straight. At this sort of speed conversation remained easily possible, but the 928 is nowhere near as sophisticated in its engine, wind and road noise suppression as the Jaguar XJ-S. It is a legion apart from the harsh 924, however, and thank goodness. There is some tyre thumping and a little roar from the ultra-low profile Pirelli P7s at moderate speed, but that is a small price to pay for the astonishing powers of roadholding with which they endow the 928.
Round the fast, twisty German secondary roads the 928 really sprang to life to reveal a standard of chassis behaviour which was both supremely satisfying in terms of driver enjoyment and superbly sophisticated in terms of reassuring comfort and safety. Understeer is not a word one associates with the 928; it simply remains neutral with the fat tyres at one with the road. Eventually it will start to drift a little, but, just as Porsche claim, that Weissach Axle keeps the car absolutely on line, even if the throttle is lifted suddenly in mid-bend. Even powering the car out of a couple of tight, damp hairpins brought the tail round only a modicum. The mind boggles at the stupidity it would require to lose this car’s adhesion terminally. Braking is so good that I almost forget to notice it.
The power is of a more gentle type than that experienced in a Carrera or Turbo, just as smoothly willing, but much softer on the small of the back. Porsche claim 0-62 m.p.h. in 6.8 sec., 0-100 m.p.h. in 13.5 sec., but it doesn’t feel like it. Yet the man-sized torque is certainly evident when trying for smooth upward changes in the lower three gears. In fact the torque is such that five gears are unnecessary, “But we consider that a keen driver would want them to improve his enjoyment,” say Porsche, ironically, in view of the 924’s lack of same. The V8’s characteristics must be ideally matched to the Mercedes automatic gearbox. The manual gearbox is perhaps the one disappointment. The gate is wide and, certainly on the test car, the lever has too much lost movement, making it all too easy to select fourth instead of second or fifth instead of third. Its hefty innards mean that strength is more essential than deftness for gear-changing. The clutch is no lightweight either, but is pleasantly smooth.
It will be some time next year before the outstanding 928 comes to Britain, when it will be priced midway between the Carrera and the Turbo. I can’t help feeling that it will spell the death-knell of the Turbo, the current pop-star cult car, for its novelty and sophistication is likely to make it the new “in” car amongst the people who buy Turbos. The 928 may not be so quick, but it is possibly better value than the Turbo — there’s a lot more motor car for the money. On the other hand the rest of the Porsche range should be unchallenged by the newcomer and Porsche anticipate being able to maintain 911 production for another four or five years, or whenever production falls from the current 50 plus per day to 25. No successor has yet been planned, but the 928 shows that is won’t have to Is a rear-engined flat-six be a perfect Porsche.