Rumors are flying left and right on what BMW has in the works to power the next-generation M3/M4, with four potential engines being spoken of. These include a turbocharged 4.4L V8, turbocharged 4.0L V8, a 3.2L inline-6 with three turbochargers and now BMW has filed a patent for a uniquely-designed twin-turbo V6.
And while the schematic is probably a bit over-the-head to us laymen, BMW breaks it down in their patent application: “…the principle of this turbocharger layout invention (#1) in a 6-cylinder internal combustion engine in V configuration (#2) with a first cylinder bank (#2a) — pictured as 3 circles and labeled with Z — and a second cylinder bank (#2b) — also pictured as 3 circles labeled with Z.”
In other words, the exhaust gases of all six cylinders are routed into one turbocharger – which BMW has said could possibly be a twinscroll unit – and once the gases exit from the turbo, they can be routed either into the exhaust system or another turbo. So in the possibility that there would be another turbocharger involved, it would be a sequential twin turbo (think bi-turbo) setup and would also allow BMW to use different sized turbochargers.
Which of these four options will BMW choose for the next M3? Only time will tell.