BMW 750d quad-turbo is the world's most powerful 6-cylinder diesel

New quad-turbo diesel engine for BMW 750d xDrive

Where the initial turbocharged engines in cars had 1 turbo, it was later found that a second turbo can be added per bank for V engines, and BMW decided a 3rd turbo would be good to up power and torque on its 3-litre 6-cylinder diesel engine to a level that would be deserving of the M50d badge, as found in the X5 M50d and X6 M50d.

But if you can add 3 turbos, could you add another?  Could you really give an engine 4 turbos?  Sure, the Bugatti engine have 4 turbos, but remember those are W16s, so effectively 2 x V8s, with a twin-turbo each.

Are there benefits to this layout?  Certainly.  BMW TwinPower Turbo technology includes multi-stage turbocharging for its 4 turbochargers.  This quad-turbo setup enables boost pressure to be built up even more quickly (compared to the previous 750d’s tri-turbo) at lower engine speeds, and therefore prompts incredibly swift responses to throttle applications from idle.  450Nm is served up from 1000Nm, with 760Nm on steam from 2000 to 3000 r/min.

The engine’s large and sustained wave of thrust and the 8-speed Steptronic transmission is tuned to make the most of it, to ensure that instant and ferocious bursts of pace can also be achieved under throttle inputs at higher speeds.

The other benefit is an 11% reduction in consumption.

BMW has indeed now increased the turbo count to 4 in its 3.0 turbodiesel engine, as to be found in the new BMW 750d xDrive and BMW 750Ld xDrive.  

The aforementioned M50d engine pumps out 280kW along with a 740Nm peak torque.  For the 750d, the numbers are up, reaching 294kW (400hp) of power and torque at 760Nm.  This engine is coupled only to the permanent all-wheel-drive, which makes sense considering the torque output.

This compares to the Audi SQ7 TDI 1-litre-bigger 4.0 TDI V8 diesel of 320kW and 900Nm.

This new BMW “d” engine stands out as a balance of combined brawn and efficiency.

The previous high-power diesel 7 Series models were not for the South African market, so its local availability is unlikely.