1985 Porsche 928S and 1987 Porsche 928S 4
The Porsche 928S continued its upward bound for 1985. Porsche stretched bore another 3 mm and -- the big attraction -- doubled the V-8’s valves and camshafts. The result was superb: 4,957cc (303 cid), plus 10.0:1 compression made possible by the four-valve head with spark plugs centrally located above new pentroof combustion chambers. SAE net horsepower came in at 288. Torque swelled to 302 pounds/feet and peaked at the lowest crank speed yet, 2700 rpm.
The Porsche 928S took a big step for 1985, getting 32-valve heads for its V-8 .
Wonder of wonders, America got the revised 32-valve 928S before Europe -- and a lot of new thrills. Car and Driver clocked just 5.7 seconds to 60, a mere 13.5 seconds to 100 mph, 14 seconds at 102 mph in the standing-quarter, and 154 mph flat-out. “These are amazing figures for a car with extremely tall economy-oriented gearing,” C/D observed dryly. “. . . [A] substantial improvement over its predecessor.”
Braking was somehow better, too, even though ABS had been left in Germany (it became standard Stateside for ’86). Car and Driver termed the system “reassuring, thanks to linear performance, well-proportioned front-to-rear balance, and excellent modulation. These characteristics contribute to the 928S’s ability to stop from 70 mph in just 175 feet. Perhaps even more impressive is [its] ability to absorb triple-digit speeds without fading or emitting any disconcerting squeals, groans or odors.”
There were few other changes for 1985, though Porsche now extended its rust warranty to an impressive 10 years. Inevitably, price was more impressive, too: a cool $50,000. Still, only a few, much costlier Italian exotics were in the same performance league, and the 928S was far more reliable, comfortable, and practical.
Amazingly, an even better 928 was on the way. It arrived for 1987 in all markets except Australia as the Porsche 928S 4 (denoting a “fourth series”). “Porsche raises the price and rewards of automotive hedonism one more time,” said Car and Driver.
And how. Emissions-legal horsepower was now 316 at 6,000 rpm, torque 317 pounds/feet at 3,000 rpm. This was accomplished with revised cylinder heads with larger valves, combustion chambers that were shallower by 3 mm, a narrower valve angle (27.4 degrees versus 28), altered valve timing, and a new, more compact two-stage intake manifold. The last comprised twin resonance chambers or tracts -- one long, one short -- feeding air to the intake pipes via a Y-shaped passage from the throttle body. Below 3,500 rpm the engine breathed only through the long tract; above that, depending on throttle position, a butterfly valve in the second tract opened to increase airflow. Porsche claimed this setup ensured at least 300 pounds/feet of torque from 2,700 to 4,750 rpm, a “fat” torque curve, indeed.
Putting the power to the ground was a larger-diameter single-disc clutch instead of the previous dual-disc unit. The ABS brakes also got attention, with a shorter-travel booster and larger pistons for the front calipers.
Further bolstering S4 performance was the 928’s first facelift, a minor one that reduced aerodynamic drag. Fog and driving lamps were newly flush-mounted in a smoother nose cap that added 2.3 inches to overall length, and the chin spoiler was now fully integrated with it. A revised cooling system featured thermostatically operated radiator shutters that opened only when needed to minimize drag in high-speed driving. Twin variable-speed electric fans replaced a single engine-driven fan that consumed more power. A “detached” wing-type spoiler flew above a smoother tail (again with flush-mount lamps). Also easing airflow were deeper rocker panels, a new belly pan beneath the engine, a bonded-in windshield, and wipers that parked 20 mm lower than before.
All this added “down” to a drag coefficient of 0.34, versus 0.41 for the original 928 and 0.38 for the previous S. That was commendable considering that, in Porsche tradition, the rear tires had grown wider than the fronts: 245/45VR16s versus 225/50VR16s (on respective rim widths of eight and seven inches).
The S4 cockpit remained familiar 928-style. Body-hugging sports seats were still available, but there were two new options for the standard power seats. One was electric lumbar support adjustable for height as well as firmness. The other was “Positrol,” a memory system that stored the positions of seat, lumbar support, and even the door mirrors for recall at the touch of a button. Both were available for either the left or right seat which, as in ’86, could be fitted with heating elements as a separate option.
As before, and as with recent 911s, Porsche would decorate a 928 interior to special order in any materials and/or colors a customer wanted. One example was done completely in ostrich leather for Jordan’s King Hussein.
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The Porsche 928S 4 5.-liter V-8 had a twin-stage manifold and 316 horsepower.
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