BMW M4 (F82) short clip: S55 twin mono-scroll turbos

BMW M4: mechanical breakdown

A 10-second F82 clip

Ten seconds of an F82 M4, captioned only with the model and chassis code. No variant, modification or event is named. What the brief confirms is the hardware: an S55, a 2979 cc twin-turbo inline-six rated at 425 hp and 550 Nm in standard form.

Two turbos, three cylinders each

Each of the S55's two mono-scroll turbochargers is fed by three cylinders. The firing order is 1-5-3-6-2-4, so the pulses that drive a given turbine come from its own group of three, not from all six cylinders merged into one housing. The turbines also take energy out of every pulse before it reaches the tailpipe, which is part of why this engine sounds raspier and less operatic than the naturally aspirated V8 in the previous M3. Active Sound Design then plays a synthesised engine sound through the cabin speakers. What the driver hears inside is therefore a blend of the real engine and a speaker feed; a camera or phone outside the car picks up only the exhaust.

Charge pipe first, then the tune

Owners start with an aluminium charge pipe, because the stock plastic one is prone to cracking under increased boost. Cost is the only real downside. An ECU tune comes next and gives significant power and torque gains, but it adds stress to the crank hub and drivetrain. The S55 crank hub can spin on tuned engines, so a pinned or keyed hub is the usual fix, and the install is labour-intensive. Downpipes add faster spool, more power and more volume; catless versions are not road-legal in many markets. Separately, the abrupt torque delivery already leaves the rear end snappy in wet or cold conditions.