This 600-hp TT has twin electric turbos

Audi TT clubsport turbo concept
At the recent 2015 Wörthersee Tour – Mecca for fans of compact German sports cars – Audi presented a very special TT to its its fans: this 600-horsepower TT clubsport turbo. A technical concept car, it combines a powerful TFSI engine with twin electric turbochargers.

Wide add-on parts and a powerful rear wing, the TT clubsport turbo impresses with its power and design. The inspiration for the show car came from the successful Audi 90 IMSA GTO of the late 1980s.

The TT clubsport turbo has a 2.5 TFSI engine with very impressive performance. From 2,480 cc of displacement, the five-cylinder engine produces 600 hp and 480 lb-ft of torque – and 240 hp per litre of displacement. Power is transferred via a manual six-speed transmission.

Thanks to lightweight design, the TT clubsport turbo show car can complete the standard sprint from 0 to 100 km/h in 3.6 seconds, and its top speed is 310 km/h. But the TT clubsport turbo plays out its big advantage over the first few meters of a sprint. Its electrically driven compressor lets it cover up to 16 m within the first 2.5 seconds – six metres further than a comparable car without this innovation – a difference of around one and a half car lengths.

The big advantage of an electrically powered compressor is that it revs up to maximum rpm rapidly and without any perceptible delay, and it continues to boost charge pressure when too little drive energy is left in the exhaust gas for the conventional turbocharger. This operating principle makes it possible to design the conventional turbocharger for high charge pressures and consequently for high engine power – the eTurbo consistently assures spontaneous response and powerful sprints from low engine speeds.

The effect is impressive. The 2.5 TFSI engine builds up its tremendous power without any perceptible delay. This power is available in any situation – whenever the accelerator pedal is pressed. In an acceleration duel, the TT clubsport turbo effortlessly pulls away from a counterpart with an equally powerful engine but no electric biturbo.

It’s not just the power of the five-cylinder engine that is fascinating – so is its unmistakable throaty sound. The exhaust system is designed for minimal back pressure; a side pipe to the ambient air is located immediately after the racing muffler. The 2.5 TFSI engine is cooled by a racing radiator. At lower engine speeds, the electrically-driven compressor boosts torque by up to 96 lb-ft.

A dedicated 48‑volt electrical sub-system – another key future technology from Audi – supplies electrical energy to the turbocharger. A compact lithium-ion battery in the luggage compartment stores the energy generated by recuperation when coasting. A DC/DC converter provides the connection to the 12-volt electrical system.

The power of the Audi TT clubsport turbo reaches the road impressively via a quattro permanent all-wheel drive system with its multi-plate clutch mounted on the rear axle for better weight distribution. A coilover suspension system enables highly precise adjustment of the body’s ride height and the compression and rebound of the shock absorbers. An electric lifting function protects the equipment from damage by street curbs. Electronic stabilization control (ESC) and torque vectoring perfectly round out the dynamic qualities of the suspension.

The show car’s 20-inch wheels have six twin-spokes and are finished in a two-colour look – both in gloss turned finish and matte black. Carbon-fibere ceramic brake discs are mounted behind all four wheels; they are very lightweight and wear-resistant. The fronts measure 370 mm in diameter.

The TT clubsport has a significantly widened track, and therefore a widened body as well – indeed, it is 14 cm wider than the road-going TT. Its angular fenders contribute their own, built-up shape to the body. They take the characteristic design of the Audi TT to an extreme, and accentuate the distribution of engine power to all four wheels. The fenders of the show car – painted in the exterior colour of Ferro Titanium – are open at the front and rear. Air from the car’s slipstream flows through them to cool the brakes. The single-frame grille and large air inlets – whose vertical fins continue the signature theme of the Matrix LED headlights – are also optimized for maximum air throughput.

An adjustable rear wing is an advanced development of the Audi Sport TT Cup, with which the brand very recently launched a dedicated race series. It is now 20 cm (7.9 in) wider, and the side flaps, which feature the four rings, were given a new geometry. The wing consists of carbon fiber-reinforced polymer (CFRP) as do all other add-on parts: the air inlets and the large splitter at the front, the side panels and side sill trims as well as the voluminous diffuser at the rear whose lateral segments reference the motif of the air inlets.

A protective “cage” of ultra-high-strength titanium tubes makes the rear zone of the interior even more rigid and safe. In front, there are lightweight racing bucket seats with four-point harnesses. The display and operating concept with the digital Audi virtual cockpit focuses on the driver, who can control all key driving parameters by using the four satellite buttons on the multifunction steering wheel.

Sporty materials such as CFRP and black Alcantara define the interior of the TT clubsport turbo. The racing bucket seats are upholstered in coral orange Alcantara and feature contrasting stitching and piping. CFRP parts with their large surfaces create sporty accents on the doors and center console, and the doors are closed by pulling on a tube-shaped grip with an Alcantara inlay. The air vents and gear shift also have coral orange accents – the aluminum gear shift lever travels in an open shift gate.