Mercedes-Benz M156 Specifications
| Engine Model: Mercedes-Benz M156 |
| Engine Type: 4-cycle 8-cylinder DOHC 32-valve liquid-cooled gasoline |
| Total Displacement: 378.8 cu.in (6.21 L) |
| Rated Engine Power: 451-518 Hp (334-384 kW) at 6800 rpm |
| Fuel System Type: Sequential multi-point fuel injection (SFI) |
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The Mercedes-Benz M156 is a 90-degree V8,
double overhead camshaft (DOHC), 32-valve gasoline engine. This
6.2-liter naturally aspirated powerplant was developed by Mercedes-AMG
as its first in-house designed and produced engine, marking a departure
from modified Mercedes-Benz production engines. Production spanned from
2006 through 2014. The M156 is an all-aluminum engine, utilizing a
sand-cast block with silicon-aluminum liners and aluminum cylinder
heads. It is an interference engine design.
The engine is renowned for its high-revving character, linear power
delivery, and distinctive exhaust note, delivering performance through
large displacement and advanced cylinder head design rather than forced
induction. Key technological features include variable valve timing
(Camtronic) on the intake camshafts, a dry-sump lubrication system, and
a sophisticated intake manifold. The M156 was engineered for
longitudinal mounting in rear-wheel-drive and all-wheel-drive
high-performance vehicles, establishing a benchmark for naturally
aspirated V8 performance in its era.
Engine Type: 90-degree V8, liquid-cooled, four-stroke gasoline engine.
Bore: 102.2 mm (4.02 in).
Stroke: 94.6 mm (3.72 in).
Displacement: 6208 cc (378.8 cu.in).
Compression Ratio: 11.3:1 (varies slightly by model year).
Firing Order: 1-5-4-8-6-3-7-2.
Cylinder Numbering: Left bank (cylinders 1-2-3-4) is bank 1; cylinder 1
is at the front of this bank. Right bank (cylinders 5-6-7-8) is bank 2;
cylinder 5 is at the front of this bank.
Engine Rotation (viewed from the front): Clockwise.
Fuel Requirement: Premium unleaded gasoline, 91 pump octane (RON 95)
minimum; 93 octane (RON 98) recommended for optimal performance.
Power Output: Ranges from 451 Hp at 6800 RPM to 518 Hp at 6800 RPM
(334-384 kW), depending on application and tune.
Torque Output: Ranges from 443 lb-ft at 5200 RPM to 465 lb-ft at 5200
RPM, depending on application and tune.
Maximum Engine Speed: 7200 RPM (fuel cut-off).
Oil Pressure (at operating temperature, main gallery): 2.0-3.0 bar
(29-44 psi) at 2000 RPM; dry-sump system pressure is higher at the pump
stage.
The cylinder block is a high-strength aluminum alloy sand casting. It
employs a closed-deck design with cast-in, plasma-sprayed
silicon-aluminum cylinder liners (Lokasil). This process creates a
wear-resistant, low-friction surface integral with the aluminum block.
The block features a deep-skirt construction with integrated main
bearing supports. The crankshaft is a forged steel unit with five main
bearings.
The main bearing caps are forged from a high-strength aluminum alloy and
are secured with four vertical bolts and two lateral cross-bolts per
cap, providing exceptional bottom-end rigidity. Connecting rods are
forged from a high-grade steel (C70). Pistons are forged aluminum alloy,
manufactured by Mahle, with a graphite-coated skirt for reduced friction
and an anodized top ring land for heat resistance. Piston pins are
full-floating and retained by circlips.
Each cylinder bank is equipped with a separate aluminum alloy cylinder
head employing dual overhead camshafts (DOHC). The cylinder heads
feature a crossflow design with large, optimized intake and exhaust
ports. The intake camshafts are equipped with variable valve timing
(VVT), known as Camtronic, providing 40 degrees of adjustment.
The exhaust camshafts are fixed. The valvetrain uses direct-acting
mechanical bucket tappets with select-fit shims for valve clearance
adjustment, located under the camshaft lobes. Valve springs are designed
for sustained high-RPM operation. The camshafts are driven by a
three-stage duplex roller chain system with hydraulic tensioners.
Valve Arrangement: DOHC, 4 valves per cylinder (32 total).
Intake Valve Head Diameter: 35.0 mm (1.378 in).
Exhaust Valve Head Diameter: 30.0 mm (1.181 in).
Intake Valve Stem Diameter: 5.5 mm (0.217 in).
Exhaust Valve Stem Diameter: 5.5 mm (0.217 in).
Valve Lift (Intake): 12.9 mm (0.508 in).
Valve Lift (Exhaust): 11.0 mm (0.433 in).
Valve Lash (Clearance): Mechanical buckets with select-fit shims.
Clearance is 0.10-0.20 mm (0.004-0.008 in) for intake, 0.20-0.30 mm
(0.008-0.012 in) for exhaust, checked cold.
Camshaft Drive: Three-stage duplex roller chain with hydraulic
tensioners and guide rails.
The fuel system is a sequential multi-port electronic fuel injection
(SFI) system. The system is a returnless design. Components include two
in-tank electric fuel pumps, a fuel filter with integrated pressure
sensor, twin fuel rails mounted atop the intake manifold, and eight
injectors.
Fuel pressure is regulated electronically by the engine control unit via
the fuel pump control module, maintaining approximately 4.0 bar (58 psi)
at the rail. The system employs an electronic throttle control (ETC)
system with two throttle valves (one per intake manifold section) for
optimal responsiveness.
Fuel Injection Type: Sequential Multi-Port Fuel Injection (SFI).
Fuel Pressure (at rail, static): 4.0 bar (58 psi).
Injector Flow Rate: 420 cc/min at 3.0 bar for standard output engines;
higher for higher-output versions.
Idle Speed Control: Managed by the ME-SFI engine control unit via the
electronic throttle body.
Idle Speed (base, in neutral): 650 ± 50 RPM.
The lubrication system is a pressure-fed, dry-sump design. This system
employs two separate oil pumps: a pressure pump and multiple scavenge
pumps. The pressure pump is located at the front of the engine and is
chain-driven from the crankshaft. Multiple scavenge pumps are located in
the sump and are driven by a separate shaft.
Oil is stored in a remote, finned aluminum oil tank, usually mounted in
the engine bay. This design ensures consistent oil pressure during high
lateral and longitudinal acceleration, prevents oil starvation, and
allows for a lower engine mounting position. The system incorporates a
water-cooled oil cooler and a replaceable cartridge-type oil filter.
Oil Pump Type: Dry-sump system with separate gear-type pressure and
scavenge pumps.
Oil Capacity (total system, with filter change): 9.5 US quarts (9.0
liters).
Oil Capacity (dry fill): 10.5 US quarts (10.0 liters).
Oil Filter Type: Cartridge-type paper element.
Oil Type (recommended): Mercedes-Benz AMG approved engine oil,
specification 229.5, 0W-40 or 5W-40 full synthetic.
Oil Change Interval: Every 10,000 miles (16,000 km) or 1 year, whichever
occurs first.
The cooling system is a pressurized, dual-circuit pump-driven system. A
belt-driven, high-capacity water pump provides circulation. The system
employs two thermostats for separate cylinder bank temperature
regulation, opening at 87°C (189°F). An auxiliary electric coolant pump
provides post-shutdown circulation to mitigate heat soak.
Coolant flows through the block, cylinder heads, water-cooled oil heat
exchanger, and heater core. The main radiator is supplemented by
separate transmission and power steering fluid coolers on many
applications.
Cooling System Type: Pressurized, pump-driven, dual-thermostat control.
Coolant Capacity: 14.5 US quarts (13.7 liters).
Thermostat Opening Temperature: 87°C (189°F).
Radiator Cap Pressure Rating: 2.0 bar (29 psi).
Water Pump Drive: Serpentine accessory belt.
Coolant Type: Mercedes-Benz antifreeze mixture (Glysantin G48 or
equivalent, silicate-based), mixed 50/50 with deionized water.
| Intake and Exhaust Systems |
The intake system features a two-piece, cast magnesium alloy intake
manifold with long, tuned runners for optimal torque delivery. The
exhaust system utilizes tubular stainless steel headers
(four-into-two-into-one per bank) that merge into dual catalytic
converters and a center muffler before splitting to dual rear mufflers.
The exhaust note is a defining characteristic of the engine.
The ignition system is a coil-on-plug (COP) design. Eight individual
ignition coils mount directly atop each spark plug. The engine control
unit provides individual coil control based on inputs from two knock
sensors (one per bank). Spark plugs are iridium-tipped with a specified
service interval.
Overall Length: 720 mm (28.3 in).
Overall Width: 780 mm (30.7 in).
Overall Height: 710 mm (28.0 in).
Approximate Dry Weight: 209 kg (461 lbs).
Engine Oil and Filter Change: Every 10,000 miles (16,000 km) or 1 year.
Shorter intervals are recommended for severe use (track days). Spark
Plugs: Replace every 37,500 miles (60,000 km) or 4 years. Air Filters:
Replace every 37,500 miles (60,000 km). Fuel Filter: Replace every
62,000 miles (100,000 km).
Coolant: Replace every 15 years or 150,000 miles (240,000 km) for
original G48 coolant. Accessory Drive Belt: Inspect every 20,000 miles
(32,000 km); replace if cracked or glazed. Timing Chain Components: Not
a scheduled maintenance item, but inspection for chain stretch and guide
wear is advised after 75,000 miles (120,000 km).
Cylinder Head Bolts (M12): Tighten in four stages using a specific cross
pattern. Final torque is 50 Nm (37 lb-ft) plus an additional 90-degree
turn plus a final 90-degree turn.
Main Bearing Cap Bolts (vertical): 30 Nm (22 lb-ft) plus an additional
90-degree turn.
Main Bearing Cap Cross-Bolts: 30 Nm (22 lb-ft) plus an additional
90-degree turn.
Connecting Rod Cap Bolts: 30 Nm (22 lb-ft) plus an additional 90-degree
turn.
Crankshaft Damper Bolt: 200 Nm (148 lb-ft) plus an additional 90-degree
turn.
Camshaft Adjuster (phaser) Sprocket Bolt: 60 Nm (44 lb-ft) plus an
additional 90-degree turn.
Spark Plugs: 25 Nm (18 lb-ft).
Oil Pan Drain Plug (on remote tank): 25 Nm (18 lb-ft).
Oil Filter Housing Cap: 25 Nm (18 lb-ft).
The Mercedes-Benz M156 engine was installed
exclusively in AMG-branded models:
Mercedes-Benz C-Class (W204, C63 AMG).
Mercedes-Benz E-Class (W211, E63 AMG; W212, E63 AMG).
Mercedes-Benz S-Class (W221, S63 AMG).
Mercedes-Benz CL-Class (W216, CL63 AMG).
Mercedes-Benz SL-Class (R230, SL63 AMG).
Mercedes-Benz CLS-Class (C219, CLS63 AMG).
Mercedes-Benz ML-Class (W164, ML63 AMG).
Mercedes-Benz R-Class (W251, R63 AMG).
Mercedes-Benz CLK-Class (W209, CLK63 AMG).
Mercedes-Benz SLS AMG (C197, GT version used an uprated M159 variant).
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