With V8s set to make way for inline-fours in Mercedes-AMG’s range, Affalterbach needs to start squeezing a ridiculous amount of power from tiny engines. With a specific output of over 200bhp per litre, the ‘M139’ that powers the ‘45 line-up is a good starting point, but it’s going to need some help, which will come in the form of electricity.
We’re not talking about hybridisation, though. Nope - AMG will be sticking motors inside its turbochargers. Mercedes‘ performance arm already has an e-turbo in the final stages of development, which will be aided by a four-centimetre electric motor.
It’s integrated onto the charger shaft, sitting it between the turbine and compressor wheels. Powered by a 48-volt electrical subsystem, it’s able to spin the compressor wheel before the exhaust gasses hit it.
This leaves Mercedes free to extract more power from small engines without creating big dollops of turbo lag. The system - which is made in partnership with Garrett Motion and uses F1-derived technology - could kill of lag entirely.
The new turbo is capable of spinning at up to 170,000rpm, slightly faster than the more conventional snail used in the M139. The turbo, its motor and all the associated electronics are hooked up to the engine’s cooling circuit to ensure nothing overheats.
We have seen electric compressors used in production cars before, and a few from Mercedes, with some of its 3.0-litre inline-sixes boosted by 48-volt-powered devices. However, these setups aren’t directly comparable, since they involve small motor-driven units working together with regular turbochargers. The new e-turbo is a very different beast and stands to completely change the character of turbocharged cars as we know them today.
The impending death of AMG’s V8 remains a huge shame, of course, but these fancy new turbos will go a long way towards making up for the 4.0 litre’s eventual ditching.