The BMW S55 marked a watershed moment for M division: the switch from natural aspiration to forced induction in the M3 and M4. Introduced in 2014, this 3.0-liter twin-turbocharged inline-six produced between 425 and 454 hp and 406 to 443 lb-ft of torque, all while spinning to a 7,600 rpm redline that kept the high-revving M character alive despite the turbos.
Engineering & Specs
The S55 uses two mono-scroll turbochargers, a closed-deck block for strength, and M-specific cooling and oiling upgrades that separate it decisively from the N55 it superficially resembles. Key highlights:
- Configuration: 3.0L twin-turbo I6 (S55B30)
- Induction: Twin mono-scroll turbochargers
- Output: 425–454 hp, 406–443 lb-ft
- Redline: 7,600 rpm
- Production: 2014–2021
The closed-deck architecture is the S55's defining trait for enthusiasts—it allows the engine to handle dramatically elevated boost, making it one of the most tunable modern M engines. Modest bolt-ons and a tune can push output well beyond factory figures.
Which BMWs Used It
The S55 saw a focused, high-performance deployment across the M lineup:
- F80 M3 — the sedan that reintroduced turbocharged M power
- F82 / F83 M4 — coupe and convertible variants
- F87 M2 Competition — the S55 in its most compact, focused package
Not sure which engine sits in a particular car? Run the chassis and options through our VIN decoder to confirm the engine before buying.
Reliability & Common Issues
The S55 is broadly robust, but a few items deserve attention. Early cars had questions around crank hub slippage under high-boost tuning, and carbon buildup on the intake valves is typical of direct-injection engines. Charge pipes, cooling components, and the usual turbocharged wear items should be inspected on higher-mileage examples. A well-maintained, sensibly modified S55 remains one of the more dependable performance sixes of its era.
Legacy
As the engine that carried M through the turbo transition, the S55 bridges the naturally aspirated era of the S65 and S54 and the newer S58 that succeeded it. It proved M could embrace turbocharging without losing its edge, and its closed-deck block earned a reputation as a tuner's dream. Explore more M powerplants in our BMW engine encyclopedia.