The Motor Sport Road Test -- Audi Coupé S2
Quietly Charismatic
It took three major appraisals before this writer was able to see beyond his blinkered “Original quattro is the best quattro” attitude to the genuine improvements that Audi engineers have provided in replacing the 1980-90 model with the cynically named S2. “Cynically” because this trades on old rally terminology for the thunderous 450 to 600 bhp Sport S1 competitors. Yet the slick S2 could not be more removed from those eye-wobbling, jaundiced-yellow, competition machine, devices that shook the earth beneath your spectating feet.
The S2 saved several thousand pounds over the outgoing list price of the final 20v original quattro. Unfortunately the UK Government’s 2.5% increase in VAT has now taken it marginally over the £30,000 barrier; tested options such as air conditioning mean that the final cost was close to that of the original quattro at £33,590.
To come to our test conclusions there were three distinct S2 driving opportunities that coloured our views. In total we drove a total of five vehicles in LHD and RHD, utilising two circuits and public roads.
Technical Analysis
At the launch of the current Coupé Audi body the most senior of engineers assured us that the obvious transplant of turbocharged power into the aerodynamic outline of the later coupé would not take place. It was admitted that it might be a long term project, but there was no motorsport motivation for Ingolstadt to become involved in mating their most powerful engines with their sleekest body. Thus it has been the road customers that have finally benefited, Audi no longer interested in doing anything more than mildly supporting customers in the rallying game that made their quattro name.
To speed development after this corporate about-face, Audi assigned their race and rally preparation specialists at Konrad Schmidt Motorsport in Nüremberg the task of squeezing the 20v inline five of 220 bhp into their later Coupé, deploying the traditional longitudinal Audi front engine position. This aluminium-headed five is also used on the LHD-only 200 saloons and was featured in later original quattro coupés.
The 20v motor has an honest heritage. It was first seen as the product of a team led by Dr Fritz Indra (now at Opel) with belt-drive to one of its twin overhead camshafts and geared drive thence to the second camshaft. It was made in limited numbers for the Sport quattro homologation special (first shown in September 1983) and produced an amiable 306 bhp from just 2.1 litres (146 bhp a litre). It was a phenomenal road car, and made the basis for a series of Sport/S1-coded rally and hillclimb cars that culminated in 598 at 8000 rpm for the winning Walter Röhrl Pikes Peak machine of 1987.
For production purposes the 20v unit gained roller chain camshaft drive and the solid valve lifters were replaced by hydraulic tappets, these moves made on the grounds of reducing noise and extending service intervals to the normal VAG 10,000 mile period. Compression ratio went from the Sport level of 8:1 to the current 9.3:1 and the turbocharger sizing was dropped from KKK-K27 to the current K24. Boost beyond atmospheric pressure was clipped from 1.03 bar to 0.85 bar. Peak power came down 86 bhp, but the torque (assisted by replacement manifolding and intercooler) peak was accessibly placed at 1950 rpm to become a major attraction.
The affable Schmidt and his team made a number of minor but significant installation changes around the proven strength of the slanted block inline five. Step one was to move the normal Coupé radiator backwards and add a secondary cooler on the right-hand side of the grille. Revised ducting led to a new home in the right-hand wheel arch for the oil cooler, and the intercooler dropped into place below the bumper line, a new apron crossmember carrying the intercooling ducting.
Both inlet and exhaust manifolding had to be changed once more, because the fit beneath the Coupé bonnet really was not an original design intention, and a classic shoehorn job (in the best possible mass production taste) was completed.
Because the baulky old “big” Audi five-speed would not fit into the Coupé floorpan without major sheet metal work, Schmidt and company opted to uprate the B-series unit found in 80/90 series cars. That ratio quintet had a torque limit of 310 Nm (228 lb ft) so the maximum boost pressure of the 200/quattro specification 20v was dropped from 0.85 bar to 0.75 bar. One major benefit is a closer second to third ratio gap and a second gear that will now permit more than 60 mph.
The motor will now run happily on the cheapest unleaded, but for the maximum outputs quoted in our data sheet and performance panels, 98 RON octane Super Plus fuel grades were employed and recommended. Such versatility is possible because the Bosch MH Motronic engine management system learns as it runs to correct fuel grade differences, being sensitive enough also to re-time the engine for optimum performance when the running-in process is completed.
Durability testing included 140,000 miles for five prototypes and a torture chamber dynamometer session for a brace of S2 engines. These were asked to complete 100,000 kms (62,000 miles) at the 6250 rpm equivalent of the 154 mph maximum velocity.
Outside the unglamorously coated engine bay, changes to the running gear betray the influence of Schmidt Motorsport. The S2 sits almost half an inch closer to the tarmac than the 170 bhp Coupé 20 and it has spring, damper (twin tube, gas-type) and anti-roll bar stiffness “boosted by between five and 10 per cent,” again compared to the normally aspirated 20v derivative.
As with the Audi V8 saloon and the BMW 750 V12, Bosch Servotronic power steering has been adopted. A conventional rack and pinion is used, but the action is made very light at parking speeds by the action of microprocessed electronics upon hydraulic assistance. The Servotronic system acts upon information received from the electrically activated speedometer. Largest visual clue to Schmidt Motorsport development input is the presence of a cross-turret brace in the motor compartment to increase substantially front-end rigidity.
High pressure hydraulics are effectively used in a quartet of disc brakes that are of the ventilated type at the front and solid on the rear; as on all Audis the driver can push a button to terminate the standard anti-lock ABS braking action at will. Similarly Audi allow the driver to lock the rear differential as required, whereas the majority of other car companies feel that these actions should be automatically dictated to the driver. We suspect that such “driver power” traces back to the powerful personal freedom philosophy of Porsche family member (and former Porsche engineer, before he fathered the quattro), Dr Ferdinand Piëch.
The 4WD system remains as it has been since the September 1987 quattro variants. Power from the longitudinally mounted engine passing through the five-speed gearbox to the central self-locking Torsen differential. Drive to the front differential remains through the ingenious Audi hollow shaft layout, which turns the cage of the Torsen unit. Rear drive is conventional, via a two-piece propeller shaft to the lockable multiple plate back differential. The latter puts the ABS out of action.
In dry surface, straight, motoring the power split remains at the original Audi quattro specification of an even 50-50, front to rear. For harder work, tight slippery corners and the like, power splits alter dramatically. These are contained within a 75:25 per cent basis (suitable for a standing start on ice) through to the logical opposite: 25 per cent front, 75 per cent rear, needed in the hardest of dry road cornering conditions.
Audi have always maintained that their 4WD extracts a modest weight penalty, and this 220 bhp 4WD is lighter than the front-drive Saab we tested last month of similar power. Audi still quote their 4WD weight handicap as 75kg/165 lb versus an equivalent front-drive Audi and plus 30 kg/66 lb against rear-drive (BMW, perhaps?). This figure is retained since the fitment of the paired half dozen Torsen worm gears. Audi were the first to utilise American Vernon Gleasman’s TORque SENsing principles in a central differential, rather than as a limited slip rear differential.
If you are interested in car technology Audi is probably the most individually innovative marque to be found in Europe. The S2 packages many such unique features as a matter of course, but it is worth recalling that inline five-cylinder petrol engines were a definite oddity at their Seventies introduction for the 100 saloon; that 4WD for production performance coupés had been confined to less than 400 Jensens, and that aerodynamics were for race tracks, Citroëns and Lotus, before Audi made them fashionable in the 0.30 Cd 100 saloon of 1982.
Audi engineering individuality now continues with the unique procon-ten stainless steel cabling to protect front seat occupants in severe head-on collisions. All UK Audis have been sold only with catalytic convertors for several sales seasons. Only Audi offers galvanised bodies throughout its range and backs up their effectiveness with a ten year anti-rust warranty, and three years protection against paint ravages. The mechanical warranty is nothing special (one year, unlimited mileage), but there is a useful six year recovery service, so long as the cars are serviced within the VAG network.
At the wheel
Can a car built for sophisticated technocrats have great driver appeal to the sentimental British? It seems not from the verdicts delivered by the majority of the British specialist press; but we beg to differ.
The original quattro coupe, albeit in 20v guise, was the writer’s 1990/91 Christmas holiday transport and he enjoyed the car as much as ever. The limpet grip in all conditions, joyous driver messages from steering and seat were reason enough to purchase. Yet more recent miles in the S2 have convinced us that it offers some important advances that will be appreciated as the Nineties unfold.
The most important item is not the largely “carryover” powertrain, but that body. Its clean lines are not particularly advanced in current aerodynamic numbers, but this bulbous body allows an 11 mph maximum speed bonus, significantly reduced noise levels at extraordinary cruising speeds, enhanced practicality (including the galvanisation process, not a part of the 1990-90 recipe) and superior ergonomics.
Externally the “V8” corporate grille, likely to be the face upon all Audis of the early Nineties, is accompanied by extended front and rear spoilers to identify the most expensive Audi Coupé from its £20,000 and under subordinates. Assisting in this class-conscious status are the five-spoke alloy wheels. Practical touches include high pressure headlamps washers and ellipsoid fog lamps that are (illegally) handy for further defining kerbs.
Most cockpit comment centres around the use of seven off white dials and grey numerals (almost reminiscent of the steam age). The information provided is generous, extending to oil temperature, as well as the more usual pressure and advice of a 7200 rpm limit; the night lighting turns the dials an illegible pink. Placing three of the instruments down on the centre console continues an Audi tradition for inviting drivers to look away from the road. Thus may you test procon-ten in anger.
Instrumentation is more tasteful and generally informative than the orange digital dash of the other quattro turbo, but boost gauge fanciers should note that this facility has been absented from the S2 as well as the later original quattros. In compensation the grey and black trim, plus deliciously decadent Jacquard satins, are superbly executed. They leave you in no doubt that Audi are a sliver above the mass production norm.
The triple-spoke steering wheel is fashionably shaped to allow excellent steering grip, but the action of the system is, at best, dubious progress. The contrast between low speed manoeuvres and violent cornering action (haplessly demonstrated by Audi in a slalom format at the 1990 presentation) is a disaster. For the steering load veers from Jaguar limousine levels to that of a single-seater racing car on heavyweight full lock: for a second you believe the power steering has failed. In normal road use, Audi steering gear has a manageable ratio, allows accuracy and does become an ally when you have extensive experience of the S2.
Initially, you may only bless the flyweight parking effort of Servotronic and wonder in amazement how the people who brought you the informative original could contemplate Servotronic in its place? Higher mileage, as for previous Jaguar systems, does instil some confidence in the driver, but this is the one aspect of the S2 that reduced our driving enjoyment; otherwise the chassis components always perform so effectively that the S2 simply soaks up high mileages imperceptibly. The ride is especially praiseworthy, far better than many executive saloons, yet one can still fling an S2 around a race track with vigour and controllable body lean.
At the heart of this supreme competence is the 4WD system, and there simply is not a better friend for the enthusiastic driver through a British winter. In typical 40 mph sidewinds and the company of a £60,000 + BMW 850i, the S2 tracked along obediently and underlined its all-round prowess for almost half as much cash as its Southern Bavarian rival.
The S2 is not embarrassed by 5-litre BMW power either. Our example did not perform remarkably by the standards of other magazines, but it was still quick enough to cope with our automatic BMW comfortably, both officially sharing the same top speed. The S2 should slip just below the six seconds to 60 mph barrier that defines Porsche 911 territory these days. Our figures, including a 6.6 second average to the mile a minute marker, are the result of just one run in each direction. These results are a convincing testimony to the S2 ability to launch itself undramatically from rest to improbable velocities: 0-100 mph was comfortably under 20 seconds and the trip to 110 mph only occupied 24.4 seconds. In this connection it is interesting to compare the similarly powerful (but even more abundantly torquey) Saab front-drive machine with the S2; on the acceleration front the Audi zips away from a standstill to 30 mph so convincingly that the front-drive Saab was left a second adrift immediately. By 100 mph the gap was still around 0.7s, so even the TCS electronic traction device of the Saab is no match for that initial standing start quattro traction.
If one compares flexibility in the gears, where no standing start element is involved, the Saab demonstrates that it really does have a pulling power bonus. It opened up nearly a 1.9 second advantage in fifth between 50 to 70 mph, always holding the upper hand in third and fourth. Fuel consumption differed little between the 220 bhp Swede and its equally powerful German opponent, within an 0.6 mpg band of 21 mpg use in similarly testing and thirsty circumstances.
Verdict
The Audi S2 Coupé is an immensely competent car, that makes us hope “one day all cars will be made this way.” The S2 is versatile and blisteringly fast, all achieved with barely a mutter from the now civil and almost liquidly powerful five cylinders in conscientiously designed and constructed coachwork. The steering is a flaw, but not a crucial one in road use. We think our readers, like the writer, would grow to appreciate the literal Vorsprung durch Technik (progress through technology) that Audi have achieved. The S2 may lack the motorsport involvement of its forerunner, but it is just as effective a weapon for Nineties motoring as was the original was in the Eighties. — JW
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MOTOR SPORT TEST RESULTS: Audi Coupé S2
ENGINE: water cooled, iron block, light alloy head; inline five cylinders and DOHC 20-valve cylinder head; KKK K24 turbocharger, intercooled, Max boost 0.75 bar (10.7 psi); capacity: 2262cc (81×86.4mm); Bosch MH Motronic electronic ignition and fuel management with over-run fuel cut-off and fault-memory diagnosis; 9.3:1 cr; Max power: 220 bhp @ 5900 rpm; Peak torque: 228 lb ft @ 1950 rpm
TRANSMISSION: Permanent 4WD, self-locking central Torsen differential and driver-operated locking rear differential. Five-speed Audi B-series gearbox. Final drive: 4.111:1
GEAR RATIOS First: 3.500; Second: 1.842; Third: 1.222; Fourth: 0.903; Fifth: 0.714 …. 24.7 mph per 1000 rpm
BODY: Steel monocoque 3-door 4-seater Coupé. Petrol tank of 70 litres. Drag coefficient 0.32 Cd
DIMENSIONS: Wheelbase, 100.4 in/2549mm; front track, 56.9 in/1453mm; rear track, 56.6 in/1437mm; width, 67.6 in/1716mm; length 173.2 in/4401mm; height, 54.1 in/1375mm. Kerb weight, 3131 lb/1420 kg.
FRONT SUSPENSION: McPherson struts, lower wishbones, twin tube dampers, anti-roll bar. Steel bracing tube between front suspension top mounting points. Steering: Power-assisted Bosch Servotronic, 3.3 turns lock-to-lock, rack and pinion. Lock-to lock: 36.25 ft.
REAR SUSPENSION: Independent action, struts, gas damping, lower wishbones and anti-roll bar.
BRAKES, WHEELS, TYRES: Power-assisted, vented 10.86 in/276mm diameter front discs; solid rears also of 10.86 in diameter. Bosch ABS electronic anti-lock braking with cabin push-button over-ride. Light alloy five-spoke 7J x 16 wheels. Kleber C555 205/55 ZR 16.
PRICE: £30,033.20p, UK taxes paid; £33,589.97p with listed options, but in-car entertainment at additional and unspecified cost. Tested Audi options: air conditioning £1,387.48; heated front seats £243.73; pre-select steel sunroof £1,133.13; Thru-load access: £179.93; electrically-activated rear window vents £612.50; Blaupunkt Heidelberg in-car entertainment system.
MANUFACTURER / IMPORTER: VAG (united Kingdom) Ltd. Yeomans Drive, Blakelands, Milton Keynes, MK14 5AN
CLAIMED PERFORMANCE max speed 154 mph; 0-60 mph 5.7s.
TEST RESULTS:
Test conducted at Millbrook Proving Ground using 1991 Correvit electronic measuring gear. Weather conditions: Dry tarmac.
ACCELERATION: 0-30 mph 2.0 seconds; 0-40 mph 3.6 seconds, 0-50 mph 5.0 seconds; 0-60 mph 6.6 seconds; 0-70 mph 9.3 seconds; 0-80 mph 11.4 seconds; 0-90 mph 14.2 seconds; 0-100 mph 18.8 seconds; 0-110 mph 24.4 seconds
FLEXIBILITY: Third gear, 50-70 mph: 4.31 seconds; Fourth gear, 50-70 mph: 6.2 seconds; Fifth gear, 50-70 mph: 8.0 seconds
Standing 0.25 mile/400 metres: 15.2 seconds @ 93 mph
Maximum speed: Millbrook 2.029 mile bowl, 149.9 mph. Best observed speed, 151.9 mph
Maximum gear speeds @ 7200 rpm: First, 35.5 mph; Second, 65.5 mph; Third, 97.3 mph; Fourth @7000 rpm, 136.5 mph
Overall Fuel Consumption: Test average, 21.8 mpg; Best, 23.6 mpg; Worst, 20.1 mpg
Government mpg figures: Urban, 20.2 mpg; @ 75 mph, 38.7 mpg; @ 56 mph, 31.7 mpg