Bowing in late 1988 for the '89 model year, the Porsche Carrera 4 -- "4" for four-wheel drive -- looked like most any recent 911 except for smoother bumpers and side sills. But appearances here deceived more than usual.
As a direct descendant of the awe-inspiring twin-turbo 959, the "C4" was nothing less than the vanguard for what amounted to a second-generation 911 design. Indeed, it was developed as a separate program, Project 964, and was said to be 85 percent new.
Subtle but noticeable body alterations marked the 1989 Porche Carrera 4.
That it was, starting with a unique floorpan shaped to smooth airflow beneath the car, plus 959-inspired all-round coil springs with integrated tubular shocks (albeit one per wheel). Rear semi-trailing arms and front struts on lower wishbones continued.
A bore-and-stroke job -- to 100 mm/3.94 inches × 76.5 mm/3.01 inches -- took the production 911's normally aspirated air-cooled flat-six from 3.2 to 3.6 liters. Engineers also applied reshaped combustion chambers, revised intake manifolds, twin-plug ignition, and ultra-high 11.3:1 compression.
In American-market trim, the Carrera 4 produced 247 horsepower at 6,100 rpm -- a gain of 34, and less than 40 shy of the vaunted Turbo -- plus 228 pound-feet of torque at 4,800 rpm. Rolling stock was upsized to suit: 16-inch Bridgestone RE71s, as on the 959. The C4 tires were more modestly sized at 205/55 fore and 225/50 aft but had the higher Z speed rating (good for 150 mph and up).
But, of course, the big attraction was the all-wheel drive that made the Porsche Carrera 4 what one reviewer termed a "people's 959." To be sure, it was drastically simpler than the Porsche 959 system, but that only helped to hold initial retail price to "just" $69,500, a huge saving over the $225,000 it took to buy a 959 -- when you could get one.
Five-speed manual transmission was mandatory in the Porsche 911 Carrera 4.
The Porsche Carrera 4's all-wheel drive employed center and rear differentials, each with an electrohydraulic multi-plate clutch. Power went forward from the engine to the center differential, then back to the rear wheels via a driveshaft housed within the countershaft of the five-speed manual gearbox; a second shaft sent power to a normal front diff and halfshafts. Both clutches were computer-controlled in response to signals from the four wheel-speed sensors of the first antilock braking system (ABS) ever offered on a "volume" 911, another big C4 attraction.
Though the center diff normally divided torque 31/69 percent front/rear, the computer could vary that through selective use of the clutches whenever the wheel sensors signaled tire slippage (as differences among wheel speeds above a preset threshold). Response time was reported at less than a tenth of a second -- three times faster than the 959 system.
Additional sensors for straight and lateral acceleration allowed the computer to engage the rear differential on lifting the throttle in a corner, thus increasing understeer and hence stability. For safety as well as longevity, both clutches disengaged under braking. A dashboard switch could be flicked to lock the diffs for maximum grip on slippery surfaces below 25 mph; above that speed, the clutches released automatically.
Here was yet another inventive Porsche answer to a customer request -- a more controllable Porsche 911 --and the company was right to term this drive system "intelligent." Further aiding stability were a front suspension modified for zero-scrub radius and new rear suspension mounts designed to vary toe angle with cornering load (like the vaunted "Weissach axle" in the Porche 928).
For straighter high-speed running, the C4's engine grille automatically powered out and up above 50 mph to become a spoiler that increased rear downforce; below 6 mph, it snugged neatly back into the lid. Porsche also claimed the appearance changes gave the C4 a 15 percent lower drag coefficient than previous 911s, plus "zero-lift characteristics at highway speeds."
For all this, some doubted the Porsche Carrera 4's ability. "The new suspension and driveline banish the 911's penchant for tail-out antics," said Car and Driver. "Throw the car into a corner while braking or suddenly lift the throttle at the limit and the Carrera 4 barely rotates; its tail stays solidly planted at all times."
Motor Trend judged real-world cornering "incredible, although the Carrera 4's ultimate...0.84 g is not as high as the Corvette's or even a Pontiac Firebird Formula. What this shows is that lateral-g numbers are just one indication of handling ability. Perhaps a better indication is slalom speed, in which the Carrera 4 [is stellar]."
Though the C4 was no 959 for acceleration, Road & Track clocked a zippy 5.8 seconds to 60 mph and 14.4 seconds at 96.5 mph in the standing quarter-mile -- close to the level of racing Porsche 911s from not too many years before. C/D, as usual, did better: a quick 5.1 seconds to 60 and 13.6 at 102 mph in the quarter.
But the real point was this: "[Porsche has] gained so much balance with the Carrera 4 that we no longer consider its discontinued cousin, the antsy 911 Turbo, a class contender among high-dollar sports cars."
What? The Turbo gone again? Yes, but only from the U.S. market -- the Carrera 4's positive response was a factor -- and only for a few years.
The "4" in the '89 Porsche 911 Carrera 4 denoted 4-wheel drive.
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|Porsche 924, 944, 968
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