Audi RS3
A five-cylinder, 2.5-litre turbocharged gasoline engine, seven-speed dual-clutch transmission and lightweight materials offer the performance and driveability that drivers expect from a hot hatch
- Published in Vehicle Development.
The five-cylinder’s 450Nm gets the RS3 to 100km/h in 4.6 seconds
The focus for the industry is undoubtedly on improving efficiency, but in some projects engineers can spend less time thinking about fuel economy and more time improving speed and acceleration.
Audi’s RS3, based on the C-segment A3, is the OEM’s latest addition to its performance vehicle line-up. Hot hatches like this are defined by performance, how fast they can reach 100km/h from a standing start, how much lateral g you can generate on challenging road layouts and, when you’re driving through populated areas, aural pleasure.
The RS3 uses the same 2.5-litre turbocharged five-cylinder gasoline engine as the one that powers Audi’s TT RS coupe. The 250kW/450Nm unit can push the RS3 from 0 to 100km/h in 4.6 seconds and on to a limited top speed of 250km/h. This new application for the engine meant that the engineers had to make adjustments to the unit.
Stephan Reil, head of technical development at Quattro, Audi’s performance subsidiary, says: “The base application is the same but I would estimate that about 20% of the engine is new. The cooling packaging on the RS3 is completely different.” And, unlike other A3 variants that are available with both manual and wet dual-clutch transmissions, the RS3 only uses Audi’s seven-speed dual-clutch.
“We discussed using both transmissions but, when you look at the split of manual to dual-clutch on the S3, you find that the dual-clutch transmission is the higher-volume technology,” says Reil.
The sales figures helped shape the choice but so did the plant the RS3 is built in. Reil’s team of 60 engineers had to choose one transmission for the vehicle: “Because the vehicle body is built in Ingolstadt and then shipped to Audi’s Györ plant in Hungary – where the TT RS and A3 convertible are built – we didn’t want to add extra complexity to the production line, so we had to make the decision whether to go for manual or dual-clutch,” says Reil. The Györ plant also makes the 2.5-litre engine, which eases some of the logistical issues.
Having made the decision to use the dual-clutch transmission, work began on meeting the packaging challenges. Much of the RS3’s architecture is similar to that of the TT RS – the longitudinal members and the transversal space, for example – but engineers had to spend more time on the longitudinal axis which is different. “The RS3 is slightly different to the TT RS so every pipe and hose from the engine to the body of the car needed replacing,” says Reil.
Taking the RS3 around the tree-lined mountain roads of Velden in southern Austria, the 2.5-litre turbocharged engine and dual-clutch transmission made for a thrilling drive. Gearshifts were responsive enough for the undulating landscape. And the engine – with maximum torque available between 1,600rpm and 5,300rpm – made overtaking slower traffic very easy.
The terrain made the brakes work hard. The iron rotors and aluminium hubs were always working within their limits, and they help to save weight. But high-performance vehicles often use more exotic materials, such as ceramics and carbon fibre.
“We considered using ceramic brakes but it would have been too expensive and the installation rate too low. The cost for ceramic brakes would have been around €8,000 – 15% of the car’s sticker price,” he says.
