The Mercedes-Benz M278.927 is a 5,461 cc, V8 twin-turbocharged petrol engine produced between 2012 and 2017. It features dual overhead camshafts (DOHC), variable valve timing (VVT), and direct fuel injection. In standard tuning, it delivered 320 kW (435 PS) with peak torque of 700 Nm, providing strong low-end responsiveness and high-speed performance for luxury and performance applications.
Fitted to flagship models such as the W221 S-Class, W218 CLS-Class, and C217 CLS-Class, the M278.927 was engineered for refined power delivery, rapid acceleration, and grand touring capability. Emissions compliance was achieved through cooled exhaust gas recirculation (EGR) and dual close-coupled three-way catalytic converters, allowing Euro 6 compliance across all production years in European markets.
One documented concern is high-pressure fuel pump (HPFP) wear observed in early production units, highlighted in Mercedes-Benz Service Bulletin 278.927-05/13. This issue is linked to inadequate lubrication under sustained high-load operation and low fuel levels. From 2014, revised HPFP internals and updated fuel system calibration were implemented to improve durability.
Production years 2012–2017 meet Euro 6 standards (VCA UK Type Approval #VCA/EMS/9901).
The Mercedes-Benz M278.927 is a 5,461 cc V8 twin-turbocharged petrol engine engineered for luxury and performance vehicles (2012–2017). It combines direct injection with twin-scroll turbochargers to deliver immediate throttle response and strong mid-range torque. Designed to meet Euro 6 standards, it balances high performance with improved fuel efficiency and emissions control.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,461 cc | |
| Fuel type | Petrol | |
| Configuration | 90° V8, DOHC, 32-valve | |
| Aspiration | Twin-turbocharged | |
| Bore × stroke | 96.9 mm × 92.4 mm | |
| Power output | 320 kW (435 PS) @ 5,250 rpm | |
| Torque | 700 Nm @ 1,800–3,500 rpm | |
| Fuel system | Direct injection (up to 200 bar) | |
| Emissions standard | Euro 6 | |
| Compression ratio | 10.0:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Two parallel twin-scroll turbochargers | |
| Timing system | Dual chain (primary and secondary), non-interference design | |
| Oil type | MB 229.51 (SAE 0W-40) | |
| Dry weight | 225 kg |
The twin-turbo V8 provides strong low-end torque ideal for relaxed cruising and rapid acceleration but requires consistent fuel system maintenance to prevent high-pressure pump wear. MB 229.51 (0W-40) oil is essential due to its low-SAPS formulation and thermal stability, protecting the turbochargers and direct injection system. Extended idling or short-trip driving increases carbon buildup and oil degradation, so 15,000 km service intervals are recommended. The engine's sensitivity to fuel quality necessitates premium unleaded (RON 95 minimum) to maintain combustion efficiency and prevent knock. Post-2014 models feature revised HPFP internals; pre-2014 units should be inspected per Mercedes-Benz SIB 278.927-05/13. EGR and intake manifolds require periodic cleaning to sustain airflow and idle stability.
Oil Specs: Requires MB 229.51 (0W-40) specification (Mercedes-Benz SIB 278.927-05/13). Supersedes ACEA C2/C3.
Emissions: Euro 6 certification applies to all production years (2012–2017) (VCA Type Approval #VCA/EMS/9901).
Power Ratings: Measured under DIN 70020 standards. Output consistent across markets with premium fuel (Mercedes-Benz TIS Doc. A33020).
Mercedes-Benz Technical Information System (TIS): Docs A32790, A32910, SIB 278.927-05/13
VCA Type Approval Database (VCA/EMS/9901)
ISO 1585:1992 Road vehicles — Test code for net power of internal combustion engines
The Mercedes-Benz M278.927 was used across Mercedes-Benz's W221/W218/C217 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-intake manifold tuning in the CLS-Class and revised cooling routing in the S-Class-and from 2014 the updated high-pressure fuel pump introduced in facelifted S-Class models improved system longevity, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front timing cover near the harmonic balancer (Mercedes-Benz TIS A32790). The 7th and 8th VIN digits indicate engine type ('4H' for M278.927). Pre-2014 models have silver cam covers with black plastic intake manifolds; post-2014 units use black cam covers. Critical differentiation from M278.926: M278.927 has a 5.5L displacement and higher torque output (700 Nm vs 620 Nm). Service parts require production date verification—high-pressure fuel pumps before 07/2013 are incompatible with later units due to internal redesign (Mercedes-Benz SIB 278.927-05/13).
The M278.927's primary reliability risk is high-pressure fuel pump wear in early builds, with elevated incidence in sustained highway and low-fuel driving. Internal Mercedes-Benz quality reports from 2015 indicated a notable share of pre-2014 engines requiring HPFP replacement before 130,000 km, while UK DVSA records show fuel system-related faults contributing to emissions test failures. Extended idling and low fuel levels reduce lubrication stability, making adherence to oil specification and service intervals critical.
Analysis derived from Mercedes-Benz technical bulletins (2013-2017) and UK DVSA failure statistics (2014-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M278927.
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Regulation (EC) No 715/2007
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