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Porsche 911 Turbo: The Uncompromising Car

by Jerry Slonger - Febuary 1991- Exellence A Magazine About Porsche Cars

A 911 Turbo is all about character - banish any thoughts of a "perfectly rounded" GT experience. Would you put arms on de Milo's Venus or tell the Mona Lisa to frown? No more could you expect Porsche to build a docile, third-generation Turbo any fool can drive well at the limits. Raw urge and brutal performance figures? An enthusiastic yes. Traction control or silky automatic box? No way. The whole point of a 911 Turbo is that satisfied glow for a good driver who gets the throttle/steering continuum just right, although they have made minor comfort concessions to suit the times. Having a Turbo around is a little like keeping a pet gorilla.

You know the beast is so tame and friendly anybody can handle it almost all the time. But still...It isn't wise to let your attention wander when conditions are less than ideal.

When Turbo II (the 300 HP, 3.0 liter model) began to run down two years ago, simply because it was based on the pre-Carrera 2/4 shell, Porsche realized they would soon face outrage and supercharger withdrawal symptoms from the small but fanatically loyal Turbo clan. More than 20,600 of Porsche's priciest and most powerful model had been sold in 15 years, to the fiercest slice among all 911 fans. A replacement was mandatory, although they shy away from the idea that Turbo III is any sort of "flagship" for Porsche as such. To Zuffenhausen it is merely the crown jewel in their 911 crown. A new one had to be more powerful, since the had to be more powerful, since the unblown Carrera 2 of 3.6 liters had almost caught up, and it had to meet stiffer noise and emissions standards. Just a tab more comfort wouldn't hurt either, so long as the driver-oriented image remained intact.

Those were the goals. The development span was barely two years, with distinct budget limits since 3000 cars a year is hardly VW Beetle level when it comes to spreading costs around. A DM 183,000 price tag isn't the limiting factor on production, incidentally. Orders exceeded their first year's output by a third before the first one was built, but each Turbo is a crafted gem and they can't do more. On one hand, only a tenth or so of the 1000 engine parts or sub-assemblies were changed, but each alteration had to be computed against the whole and peripherals take more time than new components. On the other, engine space in the tail of a quarter-century-old 911 is like a microchip: you might cram more functions in but you can't stretch the outer borders.

Like previous Turbos. Mark III falls between outrageous supercars and practical GTs. Top speed of 168 MPH and 0-60 acceleration in 4.8 seconds are more than impressive enough, not to mention a claimed 2.8 seconds from 60 back to 0. Those are figures which would have won races as recently as the 70s, when the first Turbo was announced. Once you realize that empty weight has grown to 3200 lb (2980 for Turbo II), acceleration and braking become even more remarkable, yet the car is so docile in pre-boost mode your maiden aunt of eighty could drive one down to her aerobics class. Building for both realms didn't make the engineering any easier.

For both time and cost reasons, the interior is pure 911 with switches scattered when they might fall, left-hand ignition key and a (curiously non-adjustable) steering wheel rim which obscures some part of the five dials, no matter what the driver's size. Standard Porsche seats are upholstered in leather here, with full electric adjustment, and the automatic heater/air conditioner controls are more logical - but so are they in a Carrera 2. Little is left to the options list: CD player and sliding roof are about it. Radio/tape deck, ABS, metallic paint, a new and ingenious sort of slip limiter, on board computer and air bags come with every car. That computer, operated by a wand on the left, which calls up information of choice, including boots readouts, is one of an overflowing handful of lights and digits which intrude on the dials a little. Standard airbags for both driver and passenger mandate a thicker, less graceful wheel and a glove box which is just that: space for one glove. A knee bolster comes with airbags and does reduce knee room, although you'd have to be pro basketball material to really complain.

Outwardly the new Turbo is Porsche's latest 911 shape with rounded nose and tail, bonded windshield and reduced rain guttering - even smaller, slipperier outside mirrors - all in the interest of improved aerodynamics. Added here are typical Turbo flares which actually do a better job of blending the other bulges into a more coherent 911 shape, plus the obligatory whale-tail rear spoiler. Apart from holding the tail down at speed, this was unavoidable since they had to put result is a CD of 0.36, better than 0.39 wind-tunnel art. Stability took precedence.

Chassis is basically Carrera 2, uprated for the new power level. This means MacPherson struts in front but a stabilizer of 0.8", larger than the 2's, albeit 0.03" smaller than their Carrera sport kit. Semi-trailing arms with coils and track correction are Turbo-specific since track was increased by some 4.7" to 58.8" and merely adding wheel spacers is not the Porsche way. By using ex-959 alloy wheels in 17" size they could also fit larger (12.7/11/8 in) vented and cross-bored brake discs grabbed by four-piston Brembo calipers. Tires are ultra low-profile Bridgestones for the sporty driver, Pirellis for comfort or Yokohamas as a compromise between the other two. No other rubber is approved so far and the only Turbo size will be 205/50 on 7J front rims, 255/40 on 9J rims in back. Porsche runs high tire pressures to make the 168 MPH top speed safe (more comfortable pressures are the true reason BMW and M-B "voluntarily limited" their 850 and SL respectively to 155, not a desire to pacify the environmentalists). Power steering is one welcome comfort fitting here, while the five-speed gearbox is virtually the same as that in Turbo II. It fits in the same space as a Carrera 2 box but gear wheels are wider.

Cleverest chassis touch of all is a new slip limiter, developed in conjunction with ZF. This wasn't mentioned at the first static showing in Geneva last March and some early reports have praised the completely revised handling without realizing from whence it comes. Basically, a set of laminates pressed together by a sort of cam system, this is the component which does so much to tame lift-off tail wag as exacerbated by turbo lag. Under acceleration, the lockup factor is only 20% but the minute you take your foot off the throttle, never mind braking, lockup rises to 100%. Since "solid" rear-axle drive promotes understeer, as any racer of a full-house 935 can testify, the tidy result is an immediate reduction of dreaded oversteer. Yet the tail can still be controlled on the throttle to a reasonable degree, which they emphatically do not think possible with currently-popular traction control systems. Weight distribution control systems. Weight distribution is 38/62% compared to 39/61% for a Carrera 2.

The inevitable question, on list viewing Turbo III, is why Weissach continued the 3.3 liter, two-valve six when their new, 3.6 liter engine has electronic injection, among other things. Answer: time and money. Porsche realized 300 HP would no longer suffice but they have always offered a little-known power pack for Turbo II, giving 330 HP without catalytic converter. Whereas the former U.S Turbo with cat wasn't thermically up to the new goal of 320 HP on long autobahn runs, emissions technology could be fitted relatively easily to the sport kit. Uprating a 3.6 would require far more changes to handle the massive torque and anyway 320 HP is plenty for now. (U.S. figure is 315, the same thing.) There were decisive changes such as engine-map ignition, a new, 150 Ah generator driven by a different shaft or the latest dual-mass flywheel to reduce noise. Switzerland has the world's toughest noise standards right now and III passes them, which Turbo II didn't. Hydraulic engine/transmission mounts help.

By using a KKK turbo with redesigned blades of lighter metal (they are emphatic that ceramic turbos don't last), they got more boost potential with smoother pickup and reduced lag. There is no way twin turbos could be crowded in. Since mid-range torque was the primary goal, aided by new intake piping, maximum boost could be dropped from 11.4 to 10.0 psi. Peak torque was not only raised by 44 lb-ft, to 332/4500 RPM, but they can boast of better than 295 lb-ft from 2500 to 5500 RPM, a very flat curve. Injection remains semi-mechanical K-Jetronic simply because conversion to full electronic would have taken too much time for a total recalibration. Emissions are further reduced by a separate, unregulated catalytic converter behind the wastegate. Both cats have metal cores to reduce back-pressure and save space. A water-aire intercooler was out of the bounds for cost reasons and increasing the air-air model's capacity by 50% dictated that modestly-redesigned whale tail.

An event at the start of their launch in the hills behind the French Riviera underlined Porsche's conviction that there is NO truly effective anti-theft system. Whatever you develop, details have been sent to dealers for service and the shady types have them almost immediately. Porsche lost six of its first 20 Turbos from a lot guarded by electronic gates and closed-circuit TV on one night. As the PR man said, "it proves how quiet our new Turbo must be. None of us heard them leave."

Which merely proves that the thieves had the sense to remain below 2500 RPM, where the new car is docile to the point of being bland. This is where more than 3.3 liters would help. Around 2500 the boost gauge shows your first 1.4 psi reading and if the throttle is mashed, the car goes on afterburner before, its tach needle reads 3000 RPM. From there to the 6600 red line (violent cutout at 6800 - you'll only nudge it once) the sensation is brute force and snarling action. Steady pedal pressure, on the other hand, brings smooth power buildup, like riding a rocket into orbit. The down side is a strong jerk every time you lift off to shift up a notch. Apparently this is due to the K-Jetronic throttle flap falling closed. They are working on it. The box itself is ultra-precise with short lever movements but it can't be slinky or quick with all that torque to transmit. Actually 5500 revs are ample for even hard driving, as the torque tails off above that point and the lift-off jolt becomes stronger.

Pedal pressures are moderate, the clutch requires less force now and steering is very neat with taut turn-in, yet low force demands at all speeds. You even have time now for small corrections if the tail should step out, and the steering fail to make those corrections easily. High-speed tracking is dead straight. There is no drama about that 100% lockup; it simply keeps the car stable as you exit a turn, as intended. A 911 Turbo in its latest version never loses its poise. At least not on dry pavement. On frosty roads through the Maritime Alps, however, it was definitely not a machine to take liberties with. Less brutal by at least a class than the last Turbo, it remains a rear-drive, high-performance car with true turbo lag and raw turbo takeup compared to tame blower layouts in non-Porsches. Road holding is so tenacious you might expect 4WD but ride is rougher than a Carrera 4, even if smoother than the old chassis. Braking is so good you could contravene the laws of gravity if not alert. Unlike the Carrera 4, nobody is likely to find this 911 Turbo "too tame."

And that's how it will remain. There are "no plans" for a 4WD Turbo nor one with Tiptronic. Porsche feels its small Turbo customer cabal wants a driver-oriented profile, the feeling of reward for mastering one properly. If III sells anything like its predecessors (sure bet) they also see scant reason for building it as a 3.6 either. There's no limit on production numbers though, price apart. In fact, Porsche is using computer checks to try and head off speculation in Turbo futures. It's that desirable, even for people who never drove one, and twice as desirable once you have. When you say Turbo, with capital T, you can only mean one car.