More e-turbos to come from Audi

Audi's new R&D chief has admitted the company's new world-first 'e-turbo' technology is applicable to all engines, but says the days of ever-increasing power outputs from 10- and 12-cylinder engines is over.

Speaking at Audi's annual press conference in Ingolstadt last week, newly appointed board member for technical development, Dr Stefan Knirsch, said the electric compressor technology that debuts on Audi's new SQ7 can be applied to all engine types and sizes.

"It is applicable for both petrol and diesel engines, it doesn't matter," he said, before being asked if smaller-capacity engines could also use the ground-breaking technology. "Good idea. Let's see," he said.

"The application can be for our gasoline engines but you have to look at where you put it, down or up stream and where the compressor is located in the system.

"We have already tested this technology in petrol engines with good success, and something may follow in future of course, once we develop such technology."

Potentially, that means Audi's entire engine range, almost all of which is already turbocharged, could eventually incorporate electrically-aided forced induction, including engines ranging from three to 12 cylinders and from 1.0 to 6.0-litres.

Audi's first S-badged Q7 is powered by a new 4.0-litre diesel V8 with three turbochargers – two conventional exhaust-gas turbos and a third, electrically powered 'e-compressor' which doesn't increase peak performance but is claimed to eliminate turbo lag and boost low-end torque.

The result is 320kW of power and no less than 900Nm of torque from 1000 to 3250rpm. The same engine is likely to power Audi's even larger new Q8 SUV and the company's redesigned A8 limousine flagship, both of which should appear sometime next year.

Before then, however, Audi's e-compressor tech is tipped to be seen in the next-generation RS 5, based on the new A5 Coupe to be revealed later this year.

Dr Knirsch said the e-compressor tech would be rolled out across other models in a 'top-down' strategy, starting with S and RS performance models.

"First we are launching this technology in the sporty corner and then we'll see," he said.

Audi has already revealed its new S4 sports sedan, which is due here late this year and will be powered by an uprated 260kW/500Nm 3.0-litre turbo-petrol V6 that lowers its 0-100km/h acceleration time to 4.7 seconds while reducing fuel consumption.

Dr Knirsch wouldn't say whether the next RS 4 and RS 5 would come with a more powerful, e-compresor equipped version of the same engine, or the e-compressor diesel engine in the RS 5 TDI Concept.

The super-diesel coupe was powered by a 3.0-litre turbo-diesel V6 with 283kW of power and 750Nm of torque from 1250rpm, lowering the current A5 Coupe's 0-100km/h time to just four seconds.

Either way, it's clear Audi will replace the naturally-aspirated 4.2-litre petrol V8 that powers the current RS 4 and RS 5 with a downsized fource-fed petrol V6, just as Knirsch made it clear the 6.0-litre V12 diesel in the Q7 and A8 would not be replaced.

"The V12 was a certain amount of vehicles that we stopped producing in 2014," he said. "It was very clear the V12 won't get a successor but the SQ7 TDI has a predecessor with the 4.2 TDI.

"Now the car got that sporty we decided to call it SQ7 with the electric compressor. We said let's put this in the sporty segment like we did with the SQ5."

Knirsch said downsized turbocharged engines with fewer cylinders would continue at Audi, and that massive performance increases would take a back seat to efficiency gains thanks in part to lightweighting – and presumably e-compressor technology.

"The number of cylinders won't increase in future," he said. "It's most likely they will decrease again. Over the past 10 to 15 years we've seen high-performance cars with six-, eight- and 10-cylinder engines – those days are over.

"Of course we are able to increase power still a little but, we are working on weight reduction. The cars are fast enough. No one is missing anything when the cars are faster than 300km/h.

"We're looking at the performance values of the car and this won't necessarily be just power output."

Audi engineers also made it clear that e-compressor technology would not supersede traditional turbo technology, leading to the replacement of exhaust-gas turbos with electric turbos.

That's because conventional turbo technology is already highly efficient and employs an energy source that's otherwise wasted. The SQ7's e-compressor only works at low engine speed to boost throttle response, yet still requires a larger 48-volt battery system to run it.