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 C21…
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 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.
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.
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The M278.927 offers strong performance and smooth power delivery, but early models (2012–2013) are prone to high-pressure fuel pump issues if maintenance is deferred. Post-2014 revisions resolved most lubrication concerns, so well-maintained examples exceed 180,000 km. Using correct MB 229.51 oil and adhering to 15,000 km service intervals is essential for longevity.
Primary issues include high-pressure fuel pump wear (especially pre-2014), intake carbon buildup, cam cover oil leaks, and ignition coil misfires. These are documented in Mercedes-Benz service bulletins. Turbocharger and EGR faults are less common but may occur with poor maintenance.
This 5.5L twin-turbo V8 was used in several core models: S-Class (W221 S500), CLS-Class (W218/217 CLS500), CL-Class (C217 CL500), and GL-Class (X166 GL500). All applications are petrol-powered and Euro 6 compliant. No cross-manufacturer usage is documented.
Yes, the M278.927 responds well to ECU remapping, safely yielding +40–70 kW by optimizing boost, ignition, and fuel maps. Supporting mods like high-flow intake and exhaust improve responsiveness. However, the stock fuel system and turbos limit extreme tuning, and modifications should not compromise emissions or reliability.
Moderate for a twin-turbo V8. In an S500 (W221), combined consumption is ~10.5 L/100km (~26.9 mpg UK). City driving may reach 13.5 L/100km, while highway runs can achieve ~8.5 L/100km (~33.2 mpg UK). Real-world economy depends heavily on driving style, but expect 25–30 mpg (UK) under mixed conditions.
No. The M278.927 uses a non-interference valvetrain design. If the timing chain fails, piston-to-valve contact is avoided, preventing catastrophic internal damage. However, timing chain replacement is still recommended at 180,000 km or as per service schedule to maintain synchronization.
Mercedes-Benz specifies SAE 0W-40 oil meeting MB 229.51 standard. This low-SAPS synthetic oil provides optimal protection for the turbochargers and direct injection system. Change intervals should not exceed 15,000 km or one year to prevent sludge and wear.
Comprehensive technical documentation and regulatory references
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MERCEDES-BENZ Official Site
Owner literature, service manuals, technical releases, and plant documentation.
EUR-Lex
EU emissions and type-approval regulations (e.g., CELEX:32007R0715, CELEX:32017R1151).
GOV.UK: Vehicle Approval & V5C
UK vehicle approval processes, import rules, and MoT guidance.
DVLA: Engine Changes & MoT
Official guidance on engine swaps and inspection implications.
Vehicle Certification Agency (VCA)
UK type-approval authority for automotive products.
Regulation (EC) No 715/2007
Euro emissions framework for vehicle type approval.
Commission Regulation (EU) 2017/1151
WLTP and RDE testing procedures for emissions certification.
GOV.UK: Vehicle Approval
UK compliance and certification requirements for imported and modified vehicles.
VCA Certification Portal
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