It follows the N54 and N55 turbocharged inline-six engines ... a single turbo, and a variety of outputs across five core versions (excluding the S58, the performance version from BMW's M division).

The M121 engine from 1969 developed around 276bhp at 6500rpm with 0.98 bar of boost – the turbo was theoretically capable of generating 1.76 bar but BMW was fairly confident this would have ...