Friday 29th May 2009

Audi TT RS

Audi rediscovers 5-cylinder turbocharged power for its new 335bhp sportscar

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Even as I opened my big mouth to ask quattro GmbH’s technical director whether the new Audi TT RS comes packaged with a five-cylinder turbo simply as a marketing ruse cooked-up to reconnect the brand with the glory days of the old Sport Quattros, I reckoned I might be in for a black eye.

New front end distinguishes TT RS

Fortunately the boss of Audi’s go-faster outfit is Stephan Reil. He’s a gent with a kindly demeanour who, instead of swatting me with his copy of the hefty TT RS press information pack, managed to stifle his indignation with a (politely) derisive laugh.

‘Do you see any marketing men here?’ he demanded. ‘No you don’t, because at quattro we are all engineers, and what you have come here to see is not marketing, but an engineering project, one hundred percent.’ Well, I might have guessed he would say something along those lines, but the question hadn’t seemed too daft considering the emphasis placed on the historical connection between the classic Sport Quattros and the new TT RS in the brief presentation we’d just sat through.

Stephan Reil and Audi Sport Quattro

Stephan says the five-cylinder turbocharged lay-out was chosen for the TT RS over the larger displacement six-cylinder option because it better suited Audi’s aspirations for a fine-handling and highly efficient sportscar. However, you couldn’t blame the marketing gurus if it had been they who insisted on a five-cylinder turbo motor for this hottest TT model; lighter and more compact than a six of similar output, the configuration is distinctively different and, more to the point, still ‘distinctively Audi’ to those of us old enough to remember the Sport Quattro in its hey-day.

TT RS shares 5-cylinder turbo layout

When the TT RS was first unveiled at the Geneva show in March, a soundtrack of the new five-cylinder engine was played alongside the new car. Stephan spent some time on the show stand and maintains he was amazed at the number of people who remembered the noise from last time around. ‘They kept saying the engine sounds just like those old ‘80s cars, and asking me, will the TT RS really sound like that?’ he says. ‘It took a lot of development to get the sound right, but yes, this car does remind enthusiasts of the classic five-cylinder turbocharged Audi sound.’

(Listen to Audi's new 2.5 turbocharged 5-cylinder)

The TT RS’s new 2.5-litre engine started life in the less than glamorous surroundings of the US-market VW Jetta’s engine bay, but has undergone a thorough re-work at the hands of quattro GmbH. Boasting an output of 335bhp – or 137bhp/litre – the engine is remarkably compact, with a gap between the cylinders of just 8mm helping to keep overall length to 494mm. Bore and stroke are 82.5mm x 92.8mm and the firing order is set at 1-2-4-5-3, alternating between adjacent cylinders and those further apart, which Audi says is responsible for engine’s distinctive rhythm and sound.

RS badge adorns black diamond grille

The engine weighs just 183kgs, and its features include a lightweight vermicular graphite cast iron crankcase, cast aluminium pistons and forged connecting rods.

FSI direct fuel injection injects fuel into the combustion chambers at 120bar, with a swirling motion helping to cool the cylinder walls and thus reducing the risk of knock during combustion. FSI also allows a high compression ratio of 10.0:1 which contributes to the engine’s efficiency.

The turbocharger is sizable too, theoretically able to compress 335 litres of air per second, and with relative boost pressure of up to 1.2bar. The turbo casing has its own oil supply and a cooling system supplied by its own water pump. If you don’t want to use all the power generated by this advanced new unit, Audi also claims a remarkable 30.7mpg is achievable on the combined cycle, as are the lowest C02 emissions in class at 214g/km. How nice!

Maximum speed 174mph - unrestricted

The engine is mounted transversely in the TT RS, connected to a new six-speed manual gearbox with a shorter throw. The car naturally comes with Audi’s quattro 4x4 system, with an active centre differential that can divert most of the torque to the back wheels as the fronts begin to slip. However the clever torque-vectoring rear differential just being introduced elsewhere in the Audi range is not compatible with the TT RS’s transverse engine quattro system.

Not a bad showing on the technical front then, but how does the TT RS stack up where it matters? On the road, and also in this case on the famous Belgian F1 circuit at Zolder, around which Audi had kindly invited PistonHeads to try their new sports machine on the generous presumption that we’d manage not to embarrass ourselves at the model's aptly-titled 'dynamic launch' for media. (In the end, having fallen at the first hurdle by ‘going round again’ when plied with an unexpectedly fine lunch of lobster and steak béarnaise, I reasoned that writing-off a shiny new TT RS on a damp track where former Audi Le Mans driver Michele Alboreto won a Grand Prix for Ferrari would not be conducive to future invitations. So you may be disappointed if you read on hoping for a detailed critique of the TT RS's handling 'beyond the limit'.)

Understeer, understeer...

But to rewind momentarily, I had arrived in Germany full of anticipation at the chance to get behind the wheel of this latest hot Audi. The TT is a fine driving machine in its own right, and the prospect of some blistering RS performance being added to the cocktail had naturally raised my hopes that this new car would be a riot.

Since first sampling the RS magic in an RS 2 Avant in the mid-1990s (and scaring myself witless, as I recall), the badge has generally implied to me a sort of manic over-achievement on Audi’s part, usually through a ballsy engineering-led effort to convert (relative) mediocrity to hilariously inappropriate and unexpected performance.

On paper, the TT RS delivers the goods without question, its combination of light weight (1450kgs) and high output delivering fearsome accelerative force. Audi quotes a 0-62mph time of 4.6secs, and a top speed of 174mph when the 155mph limiter is deactivated, and there is certainly no lack of performance out on the road. Driving the Coupe the couple of hundred kilometres on the test route from Cologne airport to the track left no doubt as to the commanding power available, or the ability of the quattro chassis to transfer it safely to the tarmac.

Rear view arguably most aggressive

The engine pulls strongly from low revs, with the maximum 332lb ft of torque available from 1,600rpm to the 5,300rpm mark, and with more than enough grunt to keep you interested up to the 6,800rpm rev-limiter – encouraged by the engine’s off-beat rorty growl which reverberates sonorously inside the cabin and can be further enhanced by an optional sports exhaust. Like the RS 4, the TT RS gets a Sport button that quickens throttle response and also opens a flap in the left-hand exhaust so gases exit more directly, reducing back pressure and improving the engine note at lower revs. (The flap also opens automatically in ‘normal’ mode under hard acceleration, so there’s no improvement in performance.)

If you specify Audi’s optional magnetic ride adaptive damping, the Sport button also reduces oil flow in the dampers to keep the car even flatter in hard cornering. That said, the standard chassis set-up that I tried seems to perform ably with little body-roll to unsettle fast progress, combined with a ride quality that is generally well resolved given the indisputably high level of cornering ability on tap. Driving on UK roads may amplify a sense that the damping could offer a little more subtlety at times, but hopefully we’ll get a chance to find that out in due course.

High-speed hair-do anyone?

The car’s steering is direct and well weighted too, allowing precise control of your chosen path, but the tactile leather-clad rim doesn’t feel hugely communicative and the same can be said of the chassis. It gobbles up corners in a typical quattro style; supremely secure, competent and safe, yet presenting few opportunities to truly engage with the driving experience.

It struck me en route to Zolder that perhaps the TT is simply too good a starting point for the 'classic' RS treatment. Whereas other RS models get radical chassis mods with extra anti-roll bars and bespoke componentry, the hottest TT makes do with a set of mildly uprated springs and dampers, revised suspension bushings and tweaks to the level of electric steering assist. Brakes are upgraded too, with 370mm front and 310mm rear ventilated discs gripped by four pot callipers that felt reassuringly effective on the road.

Silver mirrors standard - carbon optional

When I put it to Stephan that we might have predicted something a little more extreme in the chassis department, he maintained that extra anti-roll bars or additional bracing on the TT would have simply meant extra weight for no discernible effect. That’s all very well, but with a set-up so similar to the standard car the TT RS feels, well, pretty much just like a faster TT. There’s little sign of any of the extra personality or passion that has made the RS badge such a legend on other Audi models.

Of course on a damp-ish track, even with the ESP left resolutely on (see excuse proffered above), there is definitely an amount of fun to be wrung out of the TT RS. The car’s traction when powering out of corners is notably good, while the excellent power to weight ratio, slick gearchange and smooth delivery of power from the turbocharged engine all conspire to encourage a maximum attack approach – particularly as the quattro’s tendency to gentle understeer in extremis confers a reassuring sense of security that things are never likely to go too far wrong. The downside is a corresponding lack of engagement with the chassis, as even when lapping as fast as you might care to the car responds benignly with none of those moments of 'adjustability' that make the hairs stand up on the back of your neck when enthusiasm overwhelms ability.

A standard TT spoiler is optional, too

For some people, the performance figures and image alone will be enough to make the TT RS a hero. From its gaping front air-intakes, extended side sills and special 18ins alloys to its enlarged exhausts and pylon-mounted rear spoiler, the TT RS certainly has the looks to ensure Audi UK should have few problems selling the 400 cars a year it predicts, split 80/20 percent between the £43k Coupe and £45k Roadster.

However, in spite of its cracking new engine and the big numbers, some may feel the latest TT delivers its performance in a manner that’s just a little too unadventurous. I don't think I'm alone in wanting an RS to make me feel like a naughty schoolboy every time I gun it up the road, yet this is a car that seems to be aimed squarely at the grown-ups.

Without the RS badges, I think I'd have flown home thinking the fastest TT was quite a machine, combining mighty performance, exemplary composure and a general sense of all being right in the world of Audi. With the RS badges stuck on it, I'd like just a little more insanity please!

[skylinecrazy]

I for one think it's a stunning looking car with all the added bits and bobs.

Good to see Audi keep pumping out performance cars.