Audi is working on a revolutionary new engine that features electrically-driven turbocharging. Those who don’t have a deep affinity for the combustion engine should probably close this page right now. Using the 3.0-litre BiTDI V6 as a base, one of the turbos on Audi’s new offering is a conventional exhaust-driven unit, while the other is smaller and driven by an electric motor. Turbochargers are traditionally driven by exhaust gas from the engine, sometimes lag occurs when exhaust pressure is not high enough to force the turbine to spin and force more air into the engine.
In recent times sequential twin-turbo systems have helped remedy this problem with the smaller turbo working at low revs, before switching to a bigger one at higher revs. The benefits of this new type of engine are that the electric motor can accelerate the turbine to very high speeds almost instantly. Audi say the energy used to drive the turbo is replaced by battery regeneration, preserving overall efficiency. They also say the system is actually much simpler than current sequential twin-turbo systems.
As these very detailed and German looking technical images show, the electric turbo is located inside the induction system and is bypassed when not needed. At low engine speeds the air routed to the main turbo is sent to the smaller one, which is spinning at high speed and making boost. Tests on the prototype Audi A6 Avant find the electric system can yield a staggering two car-lengths over a conventional 3.0 BiTDI V6 in the first three seconds of acceleration. The next-generation Audi A4 may be an ideal candidate to showcase the completed technology when it goes on sale in 2014.
