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Common ModificationsServicing & Maintenance
S55 Engine Specifications
Complete technical specifications for the BMW S55 twin-turbocharged inline-6 engine.
Power Output
| M2 Competition Output | 405 HP @ 5,500-7,300 RPM |
| Standard M3/M4 Output | 425 HP @ 5,500-7,300 RPM |
| Standard M3/M4 Torque | 550 Nm @ 1,850-5,500 RPM |
| M3/M4 Competition Output | 444 HP @ 5,500-7,300 RPM |
| M2 CS Output | 444 HP @ 5,500-7,300 RPM |
| M3 CS / M4 CS Output | 453 HP @ 6,250 RPM |
| M4 GTS Output | 493 HP @ 6,250 RPM |
| M4 GTS Torque | 600 Nm @ 4,000-5,500 RPM |
| Redline | 7,600 RPM |
Core Specifications
| Engine Block Material | Diecast Aluminium AlSi7Cu0.5Mg |
| Block Deck Design | Closed Deck |
| Cylinder Head Material | Diecast Aluminium AlSi7Cu0.5Mg |
| Cylinder Wall Material | Plasma Arc Wire Spray Coating |
| Cylinder Wall Coating Thickness | 1 mm |
| Crankshaft Material | Forged Steel (42CrMoS4Mod), Nitrocarburized |
| Crankshaft Weight | 21.1 kg (46.5 lbs) |
| Crankshaft Counterweights | Symmetrical arrangement |
| Connecting Rod Material | Powdered Metal Drop Forged |
| Connecting Rod Design | Modified small end for improved load distribution at high RPM |
| Piston Manufacturer | Mahle |
| Piston Material | Aluminium Alloy (AlSi12Cu4Ni2Mg), Grafal-coated skirt |
| Piston Design | Different wrist pin location for higher RPM operation |
| Wrist Pin Diameter | 22 mm (restricted volume change design) |
| Wrist Pin Material | Steel Alloy (16MnCr5), Case-hardened |
| Bore Spacing | 91 mm |
| Bore Size | 84 mm |
| Displacement | 2,979cc (2.979 L) |
| Stroke | 89.6 mm |
| Compression Ratio | 10.2:1 |
| Connecting Rod Centre to Centre | 144.35 mm |
| Crankshaft Offset | 0 mm (No Offset) |
Note: S55 uses plasma arc wire spray coating on cylinder walls (same as N20) for reduced weight and improved heat transfer.
Turbocharger Specifications
| Turbocharger Configuration | Twin Mono-Scroll |
| Turbocharger Model | 2x Mitsubishi TD04 |
| Wastegate Type | Electronic Wastegate (EWG) |
| Peak Boost (Stock) | Approximately 17 PSI / 1.2 bar |
| Intercooler | Water-to-Air |
Valve & Timing Specifications
| Valve Construction | Sodium-filled (improved heat dissipation) |
| Intake Valve Diameter / Stem Diameter | 31.3 mm / 6 mm |
| Exhaust Valve Diameter / Stem Diameter | 28 mm / 6 mm |
| Maximum Valve Lift (Intake) | 9.9 mm |
| Maximum Valve Lift (Exhaust) | 9.7 mm |
| VANOS Adjustment Range (Intake) | 70 CA |
| VANOS Adjustment Range (Exhaust) | 50 CA |
| Valvetronic | Yes (Variable Valve Lift) |
DME (Engine Control Unit)
| DME Type | MEVD17.2.G |
| Manufacturer | Bosch |