Audi's new V6 diesel to feature electric turbocharging, new NOx technology

Audi's new V6 diesel will introduce the company's new electrically-enhanced turbocharger system, as well as a new integrated NOx and PM aftertreatment suite.

In the year 2030, more than 80% of newly registered cars and light trucks will still have an internal combustion engine on board and the number of diesel engines is likely to remain stable at today’s levels. And many of those diesels likely will be electrically turbocharged.

This prophesy came from Prof. Rupert Stadler, Chairman of Audi’s Board of Management, at the recentInternational Vienna Motor Symposium, where he confidently announced a new generation of 3.0-L V6 TDI diesel engines featuring new technologies.

As is typical in any automaker's new-engine announcement, Stadler said that compared with the current generation TDI units: "We have further enhanced their performance and smoothness, while significantly reducing their fuel consumption and CO₂ emissions." He added that four out of ten of Audi cars delivered worldwide have TDI engines—in Germany the proportion is two-thirds.

He also noted that even in the U.S., people had "discovered" the diesel engine, explaining that 30% of Audi Q7 customers there choose the TDI; the take rate on the previous-generation A3 was 50%. And Stadler announced that significant new technology is on the diesel horizon. In the pipeline is a new "power-diesel" featuring an electric turbocharger, which Audi dubs an "e-booster."

Audi was known to be developing the boosting technology but Stadler’s reference elevates it to a new level of priority. Audi's technology development boss, Dr. Ulrich Hackenberg, has claimed that with the e-booster, "You easily gain a lead of at least two car lengths in the first two seconds at the traffic lights!"

Said Stadler: "The e-booster makes it clear: Electronic and electrical expertise is essential for today’s modern drive systems."

But, initially at least, unless it is confirmed otherwise closer to introduction, the new V6 will just be available with a regular turbocharger to deliver a choice of power outputs of 160 kW and 200 kW (214 and 268 hp), with the more powerful version producing peak torque of 600 N·m (442 lb·ft). Best fuel consumption improvement is 13%, he claimed, compared with conventional turbo systems, with complementary CO₂ emissions reduction.

Full details of the new engine and its electrically-enhanced turbo system have not yet been released but Audi has stated that its design target criteria, which have been met, included the need to minimize friction losses and maximize efficiency. Also, piston rings have been optimized for minimal friction; the crankcase and newly designed cylinder heads have separate coolant loops; the up-dated thermal management system improves efficiency; and the turbocharger and the fully variable-load oil pump have been updated.

And Stadler claimed the engine will include an automotive first: a NOx storage catalytic converter has been combined with a diesel particulate filter and SCR (selective catalytic reduction) injection in a single assembly.

Audi adds that the exhaust gas aftertreatment integrated into the engine package satisfies "the most stringent of emissions legislation, including Euro 6" and reduces CO₂ emissions by an average of 15 g/km.

All this adds up to the new engine qualifying as a "clean diesel," although apparently it will not make it eligible to join Audi’s lower-powered "ultra" class of models, each of which has what the company describes as "extremely low" fuel consumption.

Complementing the new engine announcement, Audi revealed a production-ready 7-speed dual-clutch transmission for models with longitudinally mounted engines and front-wheel drive. Depending on model, the new transmission can reduce CO₂ emissions by up to 10 g/km, claimed the company.

As well as forecasting the diesel market share in 2030, Stadler said that at that time, according to current studies, some 40% of all newly registered cars will be electric or partially electric — almost two-thirds of them hybrids.

“The combustion engine has the advantage of decades of development. Such a technology does not simply become obsolete from one day to the next," Stadler asserted. "On the contrary; we will see potential to further improve diesel and gasoline engines. I believe that a 15% efficiency improvement is possible by 2020.”