Audi is working on a 3.0-litre V6 engine fitted with an electric turbocharger which works in conjunction with a conventional blower
21 September 2012

Audi is working on a new bi-turbo engine which uses an electrically-driven turbocharger to completely eliminate turbo lag and markedly increase standing-start performance.  

The prototype is based on Audi’s new 3.0-litre V6 TDI Bi-turbo engine, and is described by the company as being in the ‘development phase’. This experimental V6 diesel uses a conventional exhaust-driven main turbocharger with the small motor-driven turbocharger being used exclusively at low speeds.  

Reducing turbo lag - the gap between the driver pressing the accelerator and the effect of the turbo’s boost - has been the subject of engineer’s efforts for three decades. The fundamental problem is the need for a sufficient volume of exhaust gasses to be generated by the engine and then directed at the turbocharger, in order to get it running at high speed.   

However, when the engine is running at lower speeds, the volume of gas isn’t enough to spool the turbocharger up to its operating speed. Current turbocharged engines get around this problem by using two turbos. The smaller turbo can be brought into action with smaller volumes of exhaust gas and bridges the gap until the bigger turbo can be brought into play.  

Audi’s new system, however, totally eliminates lag, greatly boosts low-speed performance and is fundamentally simpler than the twin-turbo and triple turbo set-ups used by the likes of BMW.  

Audi’s electric turbocharger sits in the induction system, downstream of the conventional turbo and the intercooler and is normally not operative. However, at very low speeds - particularly from standstill - the air charged by the main turbo is re-directed through the electric turbocharger, which is already spinning at high speed, and pushed with much greater force into the engine.  

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A brief drive of a prototype unit in an Audi A6 showed the electric bi-turbo set-up to be dramatically effective. The torque boost from a standing start with the electric turbo in operation delivers what can probably be described as sub-supercar performance. Audi’s own tests claim that, back-to-back with a conventional V6 TDI, the electric Bi-Turbo car was two car lengths further down the road just three seconds after launch. 

This early prototype showed there was a just-definable dip in the torque delivery as the electric turbo gave way to main the turbo, but it is clear that electric turbocharging is set to significantly enhance the performance of forced-induction engines and deliver a step-change in the standing-start performance.

There’s no news on when the system will go into production, but the next-generation 2014 Audi A4, bases on the new alloy-steel hybrid MLB platform, looks likely to receive this engine.

Join the debate


21 September 2012

At last, I may enjoy driving a blown engine!



It's all about the twisties........

22 September 2012

Strange comment.

My experience of Turbo diesel installations is that the turbo is on song well under 200rpm, and  the low speed torque characteristics of these engines is significantly boosted by Turbo installations.

BMW's amazing new 381 bhp 740 Nm 45 mpg triple turbo diesel, must be considered as one of the performance engines of all time. 

We are an eon away from the early turbo petrol units with huge turbo lag.


Malo Mori Quam Foedari

2 January 2013

I am definitely enjoying your website. You definitely have some great insight and great stories.


21 September 2012

Interesting, suprised it has'nt been done before. Not as though it would take much electricity to spin up a small low friction turbo?

Is'nt the induction system upstream of a conventional exhaust turbo?

21 September 2012

First the Audi e petrol & diesel production and now this, seems the engineers at Audi have woken up!

21 September 2012

So, 70 years after low speed electric induction charging became the norm in marine diesel engines, the penny has finally dropped at Audi. Vorsprung durch alt technik!


21 September 2012

and automotive engines explains the considerable use of marine units, and their technology, in the automotive sector....


22 September 2012

Okay, not a tech head AT ALL. But whats the difference / benefits from this system (elec & conventional turbos) to the VW Groups supercharged & turbo charged engine, apart from ones diesel and one's petrol.

Supercharger runing off the crank = no lag then turbo kicks in when the pressure's up. Tried and tested and same result.

Is there a cost implecation or further fuel savings although don't the latest efficency programs (BMW ED, Merc Bluemotion) deactivate electrically driven ancilliaries to lower the drain on the system so the alternator doesn't rob a chunk of power / strain on engine, increase in MPG

Je ne comprenda pas

22 September 2012

An electric turbocharger should be cheaper all round, than a supercharger. Alot less complicated as well.



24 September 2012

... as "turbocharger" is used for exhaust driven inlet charging, "supercharger" for non-exhaust driven inlet charging. By popluar convention in English, anyway. I guess in German the terminology is different, and thence the translation mistake!


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