Porsche 928 S4 | Unique Cars and Parts

30 Mar 2015 | Author: | Comments Off on Porsche 928 S4 | Unique Cars and Parts
Porsche 928

Porsche 928


When it appeared out of the blue in 1978, Porsche’s exotic 928 shocked many people. Firstly, it dared to proclaim itself the successor to the revered 911 – but it had a front engine, and water-cooled at that. And then it sported that bulbous bumperless one-piece styling with window openings seemingly punched out of it.

Over the next decade Porsche aficionados learned, much to their relief, that the flat-six would continue alongside the V8, and they witnessed the influence of this design watershed spread in diluted form to a wider range of cars. At the same time, the range of cars from Stuttgart had advanced on many fronts, with each of the types having its moment of glory.

Most important to the Porsche marketing effort was the fact that the proper order of things had been restored. With one of the most enviable development programmes of any sportscar maker, the Stuttgart cars constantly edged forwards like over-eager drivers sitting on the grid waiting for the green light. Pole position was meant to stay with the 928S, which Porsche called its flagship, but it had been eclipsed on price not only by the almost mythical 959, but also by the rather ugly 911 Turbo SE.

But if there was one thing more confusing than a flagship which was not the dearest in the range, it must be that of a flagship which was not the fastest in the range. Being out-sprinted by the 911 Turbo was acceptable; losing out to a four-cylinder of half the size was not.

This was exactly what happened when the 944 Turbo roared into the picture with performance in the upper reaches which equalled or surpasssed the V8; however, the fifth-generation 928 had been given back the edge over its precocious junior.

This was not the first four-valve-per-cylinder version of the alloy V8 to be offered to the wealthy businessman: American customers had been driving a 5-litre 32-valve 928 known as the S3 since 1985, although this smog special was rated at 288 bhp, some 30 horsepower less than the S4, whose vast but wholly controllable 320 bhp output applied to all markets, with or without catalytic exhaust converter.

Feeding fuel to the eight hefty cylinders of the 928 was a Bosch LH-Jetronic system with over-run fuel cut-off, linked to a EZK solid-state digital ignition computer; supremely accurate fuel-flow and individual timing adjustments for each cylinder, controllled by separate knock sensors, allowed a high compression ratio of 10:1 in the TOP (Thermodynamically Optimised Porsche) head. In fact this ratio was slightly less than before, but accompanied all-round improvements: not only did the revised design produce considerably more torque, now totalling a mountainous 317 Ib ft, it also burned lower octane fuel, and suffered no loss of power whatever when fitted with the catalytic convertor required by Germany and the USA.

A central spark-plug made for even ignition within the silicon-coated cylinder, while there was no evidence of the low-rev flaccidity which afflicted small-capacity four-valve engines: peak torque was churned out at a textbook 3000 rpm, with the crest of the power curve at 6000. This meant significant gains in mid-range overtaking performance over the S2 whose lesser torque peaked at 4100 rpm.

Hydraulic dampers located the broad and massive power-plant within the narrow-lidded engine-bay. Induction was accomplished in the classic V8 manner, through the centre of the vee, with softly-polished inlet tracts adding only a couple of inches to the unit’s height. Belt tension for the two camshafts per bank was monitored electronically, and the distributor is mounted on the end of one camshaft.

A Family Car With A Lower Cd Than A Porsche?

A variety of ducts was carefully blended within the curves of the revised nose, which also incorporated a discreet spoiler: the huge ventilated brake discs were rammed full of cool air by one set, while the flow to the combined oil and water radiator was automatically controlled according to thermal load, thus minimising drag whenever possible. Undeniably a bulky car, the 928 had never been particularly sleek, a fact which one family car manufacturer’s advertising exploited in boasting that its own product had a lower Cd than a Porsche. But that embarrassing 0.39 figure had dropped to 0.34, a real achievement which is due to the softer and longer nose and tail (making the S4 3in longer than the S2), subtly widened sills, a narrow but free-standing tail spoiler, and a large undertray.

As was the practice with all Porsche cars of the 80’s, the gearbox was at the back, though in the front-engined models it was attached to the engine by a substantial torque-tube through which the prop-shaft ran. This solid connection reduced any drive-line movement, and provided a firm mounting for the gear shift, should owners have specified the no-cost option of a five-speed manual box. Standard issue, though, was the four-speed auto, and with the pulling power of an ocean-going tug surging through it many found it better to allow the car to choose its own ratios.

In many cases the torque-converter of an auto dulls the response of the engine it is attached to; not so the 928. Push the smooth throttle pedal and acceleration was immediate, building up forcibly as the revs rose and accompanied by a brief five-litre snarl. Press harder and the Mercedes-Benz four-speeder snappeed down one ratio, shoving the occupants deep into the seats while the tach needle lingered at maximum torque and the speedometer spun in moments towards licence-threatening levels.

The response was instant and predictable: the driver could feather the throttle to surge ahead in the same ratio, or instantly switch the box into a lower gear at any point he liked. Determined foot pressure would call up a second downshift with even more dramatic results, but even here the nose lifted only a whisker during take-off.

No need to anticipate overtaking moves by using the selector lever to change down, as I usually do in lesser autos – the Porsche can do the job as quickly and with no effort, at the expense of a thump as it changes from second to third at full stretch. On dry roads, the new larger 245/45 VR l6Dunlops at the back (the front retains the previous 225/50s) are easily capable of coping with the car’s power, not a chirp being heard during gearshifts, and they remain impressive over wet roads, more so probably than the benchmark Pirelli P7. But maximum throttle needs respect in the rain.

Porsche 928

It seems a pity that much of the engineering splendour of this vehicle was concealed beneath the flawless paint, for every component had been shaped from the best material for the job, and hang the expense – or at least pass it on to the customer. Not visible to the casual observer were the elegant light alloy castings which comprised the suspension. or the compact four-piston brake calipers which brought race-track stopping power to the freeway. Those alloy front wishbones were mounted in a conventional double set-up, with a combined spring/damper, to hold the front wheels in place, but the plump rump of this Grand Tourer was the home of the trend-setting Weissach axle which had inspired a new branch of chassis technology – positive rear wheel movement.

Many manufacturers were to follow Porsche’s engineers in putting the inevitable angle changes to good use, and indeed the 928 design seemed rather simple in comparison with that of the Mazda RX-7. It responds only to fore-and-aft inputs, but the effect tended to introduce toe-in on the loaded outer wheel, minimising the likelihood of oversteer if the throttle was snapped shut half way through a roundabout.

However, like any car the 928 responded best to smooth driving, and it clung through the tightest bends in a supremely predictable way. A modicum of understeer told the driver how hard he was pressing on, and if it started to increase, a gentle lift of the throttle edged the fat coupe back into line. Its width was not difficult to cope with in itself, given the direct steering.

The steering action was good, though perhaps falling short of the super-sharp feel of the 944 Turbo; assistance varied with both speed and load, giving roughly the same pleasant weight to the leather-bound wheel whether parking or travelling at 120mph. At such speeds directional stability was very good, with little reaction to side-winds, although vertical deflections did set up a squirming sensation which felt more to do with the suspension than the tyres. This was most pronounced when cresting a brow, when the car seemed to wiggle its hips before resuming its course.

Overall the Porsche 928 S4 dealt well with bumpy roads, particularly at higher speeds when the rather sharp ride smoothed out, but like other Porsches the wheels tended to crash and thump over holes and even cats-eyes, sounding uncomfortable rather than feeling uncomfortable. Tyre rumble was about the loudest single noise; the engine, sadly perhaps, was completely insulated from the driver’s ear except on full throttle. Another exception to this vow of silence was when the letter-box of a sunroof was open, which introduced a roar like an express train.

ABS was part of the package, but the normal action of the large ventilated discs and the four pads which gripped each one meant most drivers would never need to call upon its assistance. Dunlop, too, deserve credit for such rapid and consistent stopping. Opening the heavy door and tipping the seat forward exposed the two rather dainty perches in the back, separated by the massive hump of the transaxle.

These were small even for older children, and adults were unlikely to be squeezed in at all. Folding the backs down extended the luggage space quite usefully, though, giving a flat surface almost to the front seats. Surprisingly, cargo was better catered for in the Porsche than in many Station Wagons – not in terms of volume, of course, but in appointments: a tough luggage net covered the boot floor, there are strap anchorage points, and a quickly detachable cloth cover screened the boot alone or extends individually over the folded rear seats.

Supporting the front occupants were a pair of rather curvaceous seats which gripped the hips much better than they looked as if they should, with electric adjustment by some rather muddling switches down the side, and three memory positions. Yet despite all these variations, including lumbar adjustment, many found it difficult to sit comfortably for more than half an hour at a time.

Other aspects of the driving position were good: the bulky instrument housing moving up and down with the wheel, retaining a good view of the clear orange-needled dials and keeping the switches in fingertip reach. The ignition switch was also in this housing, instead of concealed at some awkward angle down on the column, while the climate was controlled by small sliders on a central panel.

There were stalks for flashers (left) and wipers (right), plus another for the Tempostat cruise control for the lazy. The handbrake lever was of the fall-away type and well sited to the driver’s right, together with a headlamp adjuster and the rear hatch release.

Extra vents were let into the door panels, and the driver also had the seat memories and the mirror controls by his right arm. Window and roof controls, though, were easily confused with the rear wash/wipe rocker, all of these being behind the T-bar gear selector. Wide-angle driving lamps in the bumper allowed for instant flashing, and augmented the already superb headlamps, while further safety features included heated washer nozzles, and a secondary windscreen wash system which blasted the glass with concentrated cleaner strong enough to remove the usual messy peppering of massacred insects.

While some claimed the 928 was not a real sportscar due to its great bulk and its mostly automatic sales, it did manage to put forward a good argument to claim such a title. Even at high cornering speeds the 928 S4 felt absolutely settled, asking for more acceleraation to squirt from the exit of the bend, which could be fed in with complete confidence in the traction available. Pinpoint accuracy was there to be exploited through the wheel, and the massive-looking vehicle flicked one way or the other with almost ludicruous ease.

Combine these qualities with the beautiful finish of components and trim and the busy quiet it exuded on the highway made it difficult to draw a distinction between the Grand Tourer and sportscar labels. It was a fine compromise in function with no compromise in execution. The biggest disappointment then was that only around 300 per year were manufactured.

Porsche 928
Porsche 928
Porsche 928

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