The Mercedes-Benz M278.922 is a 5,461 cc, V8 twin-turbocharged petrol engine produced between 2012 and 2017. It features dual overhead camshafts (DOHC), variable valve timing (CAMTRONIC), and direct fuel injection (CGI). In standard output form, it delivers 325 kW (442 PS) and 700 Nm of torque, providing strong performance and smooth power delivery across a broad rev range.
Fitted to models including the W221 S-Class, W213 E-Class, and X166 GLS, the M278.922 was engineered for flagship luxury applications requiring a balance of refinement, performance, and emissions compliance. Emissions control is achieved through close-coupled three-way catalytic converters and advanced lambda control, allowing Euro 6 compliance across all production years for applicable markets.
One documented concern is premature wear of the high-pressure fuel pump (HPFP), particularly in early production units. This issue, highlighted in Mercedes-Benz Service Bulletin 278.922-01-14, is attributed to inadequate lubrication and thermal stress on internal rollers. In 2014, revised fuel pump assemblies with improved metallurgy and oil feed geometry were introduced to enhance reliability.
Production years 2012–2017 meet Euro 6 standards for applicable markets (VCA UK Type Approval #VCA/EMS/9012).
The Mercedes-Benz M278.922 is a 5,461 cc V8 twin-turbocharged petrol engine designed for flagship luxury platforms (2012–2017). It combines CGI direct injection with twin-scroll turbochargers to deliver strong mid-range torque and rapid throttle response. Designed to meet Euro 6 standards, it balances high output with improved fuel efficiency over naturally aspirated predecessors.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 5,461 cc | |
| Fuel type | Petrol (Unleaded, 95 RON min) | |
| Configuration | 90° V8, DOHC, 32-valve | |
| Aspiration | Twin-turbocharged | |
| Bore × stroke | 98.0 mm × 90.5 mm | |
| Power output | 325–368 kW (442–500 PS) | |
| Torque | 700–800 Nm @ 2,000–4,000 rpm | |
| Fuel system | CGI direct injection (up to 200 bar) | |
| Emissions standard | Euro 6 | |
| Compression ratio | 10.5:1 | |
| Cooling system | Water-cooled | |
| Turbocharger | Twin variable-vane turbochargers (hot-V configuration) | |
| Timing system | Double-row roller chain (front-mounted) | |
| Oil type | MB 229.51 (SAE 5W-40) | |
| Dry weight | 228 kg |
The twin-turbo V8 provides strong low-RPM torque ideal for grand touring but requires strict adherence to 15,000 km oil change intervals using MB 229.51 specification oil to prevent high-pressure fuel pump and turbocharger wear. Use of incorrect oil viscosity or extended intervals can accelerate HPFP degradation. Cold-start idling should be minimized to ensure prompt oil pressure buildup. CGI injectors are sensitive to fuel quality and require regular use of premium unleaded (98 RON) to prevent coking. Post-2014 models feature revised fuel pumps; pre-2014 units should be inspected per Service Bulletin 278.922-01-14. EGR and intake manifolds are prone to carbon buildup in short-trip driving, necessitating periodic cleaning.
Oil Specs: Requires MB 229.51 (5W-40) specification (Mercedes-Benz SIB 278.922-01-14). Supersedes ACEA C3.
Emissions: Euro 6 certification applies to all M278.922 models (2012–2017) (VCA Type Approval #VCA/EMS/9012).
Power Ratings: Measured under DIN 70020 standards. 368 kW output requires premium fuel (98 RON) and specific ECU calibration (Mercedes-Benz TIS Doc. A50015).
Mercedes-Benz Technical Information System (TIS): Docs A50010, A50015, SIB 278.922-01-14
VCA Type Approval Database (VCA/EMS/9012)
DIN Standards: DIN 70020 Engine Power Measurement
The Mercedes-Benz M278.922 was used across Mercedes-Benz's W221/W213/X166 platforms with longitudinal mounting and no licensed external applications. This engine received platform-specific adaptations-shortened intake manifolds in the GLS and revised cooling routing in the E-Class-and from 2014 the facelifted W221 models adopted updated fuel pump designs, creating interchange limits. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped horizontally on the front of the cylinder block, near the timing cover (Mercedes-Benz TIS A50005). The 7th VIN digit indicates engine family ('M' for M278 series). Pre-2014 models have silver cam covers with black plastic intake manifolds; post-2014 units use black cam covers. Critical differentiation from M278.920: M278.922 has a hot-V turbo layout with higher compression ratio. Service parts require production date verification - fuel pump kits for engines before 08/2014 are incompatible with later units due to internal redesign (Mercedes-Benz SIB 278.922-01-14).
The M278.922's primary reliability risk is high-pressure fuel pump wear on early builds, with elevated incidence in urban and short-trip driving. Internal Mercedes-Benz quality reports from 2015 indicated a significant share of pre-2014 engines requiring fuel pump replacement before 120,000 km, while UK DVSA records link a portion of emissions-related MOT failures to EGR clogging in infrequently driven vehicles. Frequent cold starts and extended idling increase HPFP and turbo stress, making oil quality and interval adherence critical.
Analysis derived from Mercedes-Benz technical bulletins (2012–2017) and UK DVSA failure statistics (2015–2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about MERCEDES-BENZ M278922.
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