Beyond Measure

There are people in this world who think that real Porsches have air cooled engines at the back, and sometimes there's a feeling that the Zuffenhausen company's top management agrees. This year Porsche's own 'one make' championship switches from the 944 Turbo model to the 911 Carrera 2, and the chance to drive the new cars at Hockenheim before the season began was a reminder of the delights of pur sang Porsche motoring.

With a little more power and a lot less weight, the racing versions recapture the classic elements of the best loved 911s of years gone by, the original 2-litre 911s and the 2.7-litre 911 Carrera RS being the leading examples. Comparison with the Carrera RS, built in 1973, is interesting. That car, a collector's prize nowadays, weighed 980 kg and developed 210 bhp; the Carrera Cup car has been lightened drastically to 1120 kg but develops 265 bhp. The modern example has a power to weight ratio of 236 bhp per tonne, against 214 bhp per tonne for the RS, and a level of performance that would leave the RS struggling . . . . only a short way behind along the straights, but far behind around a circuit.

The 911 Cup car reaches high standards of performance despite the retention of ABS braking and full three-way catalytic equipment, developments that certainly existed 17 years ago but were only of marginal interest. Technically the latest model from the Weissach team is quite advanced, but luxurious it is not!

It's amazing how much louder the 911 becomes when all the soundproofing has been taken out. Mechanical whirrings and chatterings flood through the wall from the rear engine compartment, and even the coil-sprung suspensions make a definitive noise when the car is rolling along the pit lane. Small stones clatter against the underbody (it's years since road debris could be heard) and with a wheel off the road peppering can become deafening!

As for the engine, the main difference is the removal of the air cleaner and filter. Not much, you'd think, but the real symphony of the boxer engine comes through in stereo, just as it did many years ago before a more sophisticated clientele asked for quiet, please. The hardening of the engine note, and the quickening of response as the engine steps on to the cam are reminders of another age when Porsches were often driven to their limits, as laws allowed. The company has built 50 race-spec 911s and sold 40 to customers in Germany, Switzerland, Austria, even Italy and Sweden, but the 10-race series is concentrated in Germany in its first year (France and South Africa will continue their series with the 944 Turbos for another season).

There were some familiar names in the list of 40 for the first race at Zolder on April 1, young men like Andy Bovensiepen, Rolf Goering and Peter Zbinden — some not even born when the 911 was introduced — but mostly they're unknowns who hope to make their name, as did Roland Asch whose second 944 Turbo Cup title earned him a works-assisted drive in a Mercedes 190E 2.5-16.

If you read between the lines, it could be true that the 944 Turbo model will be phased out in August, and that Porsche's single four-cylinder model will be a 230 bhp 944s with cosmetic body changes. It made no sense, therefore, to continue with the Turbo Cup series, but there was every reason to continue the successful onemake championship with the modernised 911 Carrera 2. Altogether 150 orders were received for the 40 customer cars which have been sold for DM 123,000 apiece, ready for the track; for comparison, the standard Carrera 2 costs DM 103,500. Deposits of DM 25,000 will be returned to customers after the eighth race, and Porsche has retained 10 cars, three which will appear regularly for guest drivers. Porsche's most renowned engineer, Herbert Linge, is in charge of the series assisted by Roland Kussmaul, responsible for development (his association with the 964 goes right back to the Gruppe B study in 1983), and Jost Capito who co-ordinates the series.

The engine is easily dealt with. Although Porsche guarantees 250 bhp from the emission controlled, 3,600cc engine the average in production is 255-258 bhp. "We take the best of those" explains Kussmaul, "and really we just remove the filters, which are quite heavy, the power steering pumps and tunes them carefully. Each one is checked on the dynomometer and they give between 268 and 272 horsepower".

Porsche pioneered the technique of controlling emissions with all-metal catalysers and ran them successfully on the Turbo Cup cars last year, then equipping the latest 964 Turbo with the ceramic-free devices. Johnson Matthey, the British specialist manufacturer, is a partner in this development and is a subsidiary sponsor of the Carrera Cup series. Other suppliers include Bosch, Shell, Bilstein, Pirelli, Recaro, Emitec, and Pagid brake materials . . . . Blaupunkt is a major sponsor but clearly not a supplier!

It had been intended to equip the cars with 'short' ratios between second and fifth, but tests at the Nürburgring indicate that the cars would be undergeared, badly so for the Avus-rennen where the third round is held in May. The transmission remains absolutely standard, including gear ratios, final drive and 40 per cent differential lock, but Sachs sintered metal clutch faces are specified.

All the seating has been removed, all the trim is gone and so is the underbody and bulkhead soundproofing; or rather, bare bodies were taken straight from the production line in Works 5 and trucked to Wilfred Matter's workshop in Bruchsal, where the steel roll cage was installed. They were returned to Zuffenhausen where mechanical elements were installed, plus the single Recaro seat for the driver, and final preparation was carried out at Weissach (the 944 Turbos went through virtually the same processes, but were finished off in the customer department at Zuffenhausen). Altogether 230 kg is removed from the 911's weight, reduced from 1350 kg to 1120kg (with an empty fuel tank), and that's about the weight of three male adults. Apart from the obvious and visible measures, weight has also been cut by installing old-fashioned window winders instead of electric motors, simplifying the heating system and removing the fan ("it still has a heater, but not so complicated"), and by fitting an aluminium front lid. The engine cover remains standard, even to the electrically operated rear wings which are seen to rise as the cars head for the first corner. Underneath the car the modifications are more serious. Power assistance is no longer required for the high geared rack-and-pinion steering, the more powerful brake system is taken from the 964 Turbo with four-piston calipers and cross-drilled discs (the servo is retained, being an integral part of the ABS system), and the springing and roll resistance have been greatly stiffened.

Carefully tuned Bilstein gas dampers are fitted, and these have metal-to-metal couplings at the top. Harder rubbers are used throughout the suspensions, the four road springs are shorter, and about three times heavier than standard (there are no torsion bars nowadays on the modern 911s). Aluminium roll bars were tested but found not to be strong enough, so steel bars are now used increasing the roll stiffness about two-and-a-half times. The front bars have five points of adjustment, the rear bars three.

The suspensions are lowered by 50mm, and the cars run on special Speedline alloy wheels looking like those on the 959, and 964 production cars. They're 17 inches in diameter with 8J rims at the front, 9.5J rims at the rear, and run on specially made Pirelli slick tyres, or grooved for wet races. For the record (and in years to come this article may be referred to many times!) the tyre sizes are 245/620-17 at the front and 265/630-17 at the rear.

No claims have been made for the performance of the racing versions but it's bound to be even more impressive than the road going Carrera 2. It would be surprising if the claimed 0-100 km/h (62.1mph) time of 5.7 sec wasn't reduced to a reliable 5.0 sec, and if the maximum speed wasn't nearer to 170 mph than the standard 161 mph. The 911's Cd figure of 0.32 is likely to have been improved by fitting snug, aerodynamic rearview mirrors and by lowering the car, in spite of the fitment of 1-inch wider front wheels. Going back to the 911 2.7 Carrera RS for the moment, tests indicated a 0-60 mph time of 5.5 seconds and a maximum of 150 mph.

Through the corners there'd be no comparison between the two models. The ducktail 2.7 was a very sporty car indeed in its time, but it had handling limitations which needed to be respected. In standard form it arrived on 6-inch front/7-inch rear Fuchs alloy rims and Pirelli Cinturato tyres, and up to a point it held on very well . . . . once over the limit though, the rear engine quickly transferred itself to the leading aspect of travel.

There is the main difference. Until the Carrera 2 came along last October it was supposed that the four-wheel drive technology of the 959 and Carrera 4 was the principal reason for the Porsche's newfound road behaviour. The Carrera 2 proved convincingly that the latest chassis, coupled with suspension improvements and tyre developments, have transformed the inherent stability of the six-cylinder family beyond measure. Increasing familiarity and confidence around the Hockenheim short circuit didn't reveal any flaws. The 911 Cup car understeered a little in the many slow turns in the stadium and behind the pits, and the rear tyres edged outwards in the faster turns onto the main straight, and at the end of it. It became rather wriggly near the limit but not once did the 911 feel as though it would turn around and bite the driver (a Swiss journalist spun five times in his 20 allocated minutes, but seemed to have been very imprudent!).

The gearchange is now remote, and very high quality, contributing to the pleasure of driving the Cup car. The brake system was surprisingly powerful (we're not used to having a servo in a track car), and it took a while to realise that we'd never lock the wheels, not with ABS. Like the real racers we had to learn to brake into the corners, as late as we dared, because the wheels wouldn't lock and the car wouldn't become dangerously unstable.

All the same, it felt much better driven in the approved style, braked in a straight line and powered into the corners. The 40 racers won't worry about points for style, so long as they're first into the turns!

Here is today's ultimate Porsche 911, a superbly sporting machine with fine manners and a terrific smile-factor. It's yet another classic from the Zuffenhausen firm.

MLC

Brief specification

Porsche 911 Carrera Cup model:

Two-door type 911/964 body shell with aluminium front lid. Single Recaro seat, no passenger seating, trim or soundproofing. Weight reduced to 1120 kg including Matter steel roll cage, and fire extinguisher.

Suspension: heavy duty steel springs, fully adjustable competition steel anti-roll bars, lowered by 50mm and with Bilstein gas dampers. Brakes: from 911/964 Turbo, internally ventilated and crossdrilled. Four-piston calipers, servo and Bosch ABS. Steering, high ratio rack without servo.

Engine: standard Carrera 2 flat-six, 3600cc, with three-way metal catalytic converter. The engine has twin-plug ignition and a compression ratio of 11.3: 1. With filters removed and optimised settings the Cup car engine develops a min of 265 bhp at 6700 rpm.

Transmission: standard 5-speed manual gearbox and ratios, with 40% limited slip differential.

Wheels: Speedline forged alloy, 8J x 17 front and 9 1/2J x 17 rear. Control tyres, Pirelli slick or grooved, 245/620-17 front and 265/630-17 rear.

1990 programme

April 1, Zolder, Belgium; April 22, Niirburgring; May 6, Avus, Berlin; June 16/17, Niirburgring; July 1, Norisring; August 5, Diepholz; August 19, Niirburgring; September 16, Singen; October 14, Hockenheim.

* One more round to be notified.