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Engine: Powerful, innovative and efficient

Nov 17, 2014
The AMG 4.0-litre V8 biturbo engine is a new development and the pounding sporty heart of the new Mercedes-AMG GT. The strengths of this innovative eight-cylinder include outstanding power delivery, systematic lightweight construction and high efficiency and environmental compatibility. With an output range from 340 kW (462 hp) to 375 kW (510 hp) and maximum torque from 600 to 650 newton metres, the new AMG V8 delivers performance at motor racing level. The new sports car engine follows an impressive V8 tradition, which it continues with trailblazing features.
Powerful V8 engines have long been a core competence at AMG, the performance brand of Mercedes-Benz. The plant in Affalterbach spawns innovative and exciting high-performance engines. On this occasion, Mercedes-AMG GmbH is entirely responsible for both development and production.
First sports car engine with 'hot inside V' and dry sump lubrication
The new AMG V8 engine has two turbochargers which are not mounted on the outside of the cylinder banks but rather inside the V configuration – experts call it a 'hot inside V'. The benefits are a compact engine design, an optimum response and low exhaust gas emissions. Dry sump lubrication allows the engine to be installed lower, which moves the centre of gravity closer to the road and forms the basis for high lateral acceleration. The M178 (in-house designation) from AMG is thus the world's first sports car engine with hot inside V and dry sump lubrication. With a dry weight of 209 kg the new AMG V8 is also the lightest engine in its competitive segment.
The new AMG M178 V8 engine at a glance:
Mercedes-AMG GT S
Mercedes-AMG GT
Cylinder arrangement
Cylinder angle
Valves per cylinder
3982 cc
3982 cc
Bore x stroke
83.0 x 92.0 mm
83.0 x 92.0 mm
Cylinder spacing
90 mm
90 mm
Compression ratio
10.5 : 1
10.5 : 1
375 kW (510 hp) at 6250 rpm
(6000-6500 rpm*)
340 kW (462 hp) at 6000 rpm
Output per litre
94.2 kW/litre
128 hp/litre
85.4 kW/litre
116 hp/litre
Max. torque
650 Nm at 1750-4750 rpm
(1750-5000 rpm*)
600 Nm at 1600-5000 rpm
Torque per litre
163.2 Nm/litre
150.7 Nm/litre
Maximum engine speed
7200 rpm
7200 rpm
Maximum charge pressure
1.2 bar
1.1 bar
Peak pressure
140 bar
140 bar
Engine weight (dry)
209 kg
209 kg
Emissions standard
Euro 6
Euro 6
* in conjunction with AMG DYNAMIC PLUS package
Superior and finely metered power delivery
As the latest member of the Mercedes-Benz BlueDIRECT engine family, the AMG M178 stands out by virtue of its superior power delivery and motorsport-inspired performance. It boasts an emotive and unmistakable enthralling AMG V8 engine sound, along with immediate response and high pulling power. The torque curve is synonymous with good driveability: The GT S delivers its maximum torque of 650 newton metres in a wide engine speed range from 1750 to 4750 rpm – and up to 5000 rpm if the customer opts for the AMG DYNAMIC PLUS package.
The new V8 also stands out with its precise power output, which is easily a match for a naturally aspirated engine. This is a development objective that the AMG engine specialists put their heart and soul into and which underlines their considerable expertise. The driver truly appreciates the AMG engine, particularly in M or Race mode in the selectable drive modes, thanks to its linear power delivery, which makes it significantly easier to handle the vehicle at the limits. To ensure this the engine electronics even take the current driving status into account, as well as any lateral forces.
Third-generation direct petrol injection with piezo injectors
With a displacement of 3982 cc, in terms of technology the V8 is closely related to the AMG 2.0-litre turbo engine in the A 45 AMG, CLA 45 AMG and GLA 45 AMG, which is presently the most powerful, series-production four-cylinder engine in the world. Both AMG engines have the same bore/stroke ratio, guaranteeing high revving ability. Mixture formation comes courtesy of third-generation direct petrol injection with piezo injectors. The highly efficient and economical AMG 4.0-litre, V8 biturbo engine meets the Euro 6 emissions standard and the maximum particulate emissions level that takes effect in 2016.
Cylinder bore liners featuring NANOSLIDE® technology
The aluminium crankcase is produced using sand casting technology and features a closed-deck design. This ensures extreme strength while keeping the weight as low as possible, and allows high injection pressures of up to 140 bar. The cylinder bore surfaces feature NANOSLIDE® technology which makes them twice as hard as conventional cast-iron linings.
Daimler researchers began work on NANOSLIDE® in 2000, and the technology has so far been used in over 200,000 engines since 2006. The world's first unit with NANOSLIDE® technology was an AMG V8: the M156 as the extremely successful predecessor to the new AMG 4.0-litre biturbo. The application scope for this multi-award-winning technology has been continually widened. Since the start of the 2014 race season it is also being deployed in the new Mercedes F1 V6 turbo engine.
'Spectacle honing' is another measure to reduce friction and therefore consumption: in this complex process, the cylinder liners receive their mechanical surface treatment when already bolted in place. A jig resembling spectacles is bolted to the crankcase in place of the cylinder head mounted later. Any cylinder warpage that might occur during final assembly is therefore taken into account or eliminated as the cylinder liners are honed. This has advantages in terms of both durability and oil consumption. The new AMG V8 has forged aluminium pistons featuring a lightweight design and high strength. A low-friction piston ring package reduces fuel and oil consumption.
High rigidity for good engine acoustics and vibration comfort
The rigidity of the crankcase was optimised to improve the engine acoustics and vibration comfort. Integrating the timing case into the crankcase casting allowed connecting points to be minimised and rigidity to be increased. This particularly benefits the noise level of the chain drive.
Great attention was also paid to increased rigidity in the engine and transmission mounting areas. Thanks to these design measures, the V8 sports car engine meets the highest standards in terms of acoustics and vibrations.
Dry sump lubrication for high lateral acceleration
Thanks to the use of dry sump lubrication, a conventional oil pan is redundant. Already installed low down, it was thus possible to lower the engine by a further 55 millimetres. This lowers the vehicle's centre of gravity, which is ideal for a sports car with extremely high lateral dynamics. In addition to improved agility, dry sump lubrication ensures direct oil extraction from the crankcases for optimal engine lubrication, even at high speeds on bends.
In the M178, dry sump lubrication deploys a suction pump, a pressure pump and an external oil tank with a capacity of 12 litres. The system circulates nine litres of engine oil in total. The oil suction pump extracts oil directly from the crankcases, cylinder heads and valve body assembly and delivers it to the external oil tank at a pump output of up to 250 litres per minute. Lubricant remains there for just five seconds before being pumped back around the high-performance engine. Efficient engine oil suction improves engine efficiency further. On-demand control of the pressure oil pump takes into account the engine rpm, temperature and load characteristics stored by the control unit. In line with the lightweight construction principle, the oil sump is produced in plastic.
Cylinder heads with zirconium alloy
The cylinder heads in the AMG 4.0-litre, V8 biturbo engine are made of a zirconium alloy for maximum temperature resistance and thermal conductivity.  Four overhead camshafts control a total of 32 valves. Camshaft adjustment on the inlet and outlet side enables an excellent response and optimises the gas cycle for each operating point. Optimised valve springs and the low-friction valve gear with cam followers deliver further fuel savings.
Direct injection with spray-guided combustion
A combination of biturbocharging and direct petrol injection with spray-guided combustion increases thermodynamic efficiency, thereby reducing fuel consumption and exhaust gas emissions. Particularly fast and precise piezo injectors spray the fuel at high pressure into eight combustion chambers. Multiple injection occurs on-demand, ensuring a homogeneous fuel/air mixture. The delivery of fuel is electronically controlled and fully variable for a fuel pressure between 100 and 200 bar.
Biturbocharging with 'hot inside V'
Unlike the previous, conventional approach, both exhaust gas turbochargers in the new M178 are located inside the 'hot inside V' configuration rather than on the outside of the cylinder banks. The advantages of this layout are that the V8 engine is considerably more compact, which enables optimum weight distribution between the front and rear axle, as well as the low installation position.  The 'hot inside V' also optimises the supply of fresh air to both exhaust gas turbochargers. Electronically controlled blow-off valves ensure a very immediate and direct response. The maximum charge pressure is 1.2 bar for the GT S and 1.1 bar for the GT. The turbochargers reach a maximum rotational speed of 186,000 rpm. For combustion purposes, 2.3 times more oxygen atoms are channelled into the turbocharged engine than would be the case in a naturally aspirated engine. The two firewall catalytic converters in thin-walled ceramic material positioned down from the exhaust gas turbochargers respond very quickly due to their close-coupled configuration. In conjunction with two metal, underfloor catalytic converters, the M178 delivers effective emission control.
Performance exhaust system with fully variable exhaust flaps
Excitement, emotive appeal and recognition value: at Mercedes-AMG engine sound is an important objective during the development process. A performance exhaust system with fully variably controlled exhaust flaps is used in the GT S. The selectable exhaust system is also available as an option for the Mercedes-AMG GT.
This allows the driver to vary the engine sound: Depending on the selected driving mode, the driver experiences the new AMG V8 with a focus on comfort and relaxed, long-distance journeys or with a more emotive, motorsport-inspired touch. The M178 has its own tonal characteristics which denote the GT's membership of the AMG family, but also clearly distinguish it from all other high-performance cars.
There is an exhaust flap on either side of the rear silencer which is actuated variably on a logic-controlled basis depending on the transmission mode, driver's power requirement and the engine speed. At low loads and engine rpm the flaps remain closed. This causes the exhaust gases to cover a longer distance and flow through an additional damping element so that the engine sound is pleasantly subdued and irritating frequencies are effectively suppressed. When the driver accelerates, the flaps progressively open so that although some of the exhaust gases cover the longer, acoustically dampened distance, most travel the shorter distance. Under full load at higher engine speeds, both flaps are fully opened, thus allowing the occupants to enjoy the powerful sound typical of an AMG V8. This means that one can hear and feel the performance potential residing in the eight-cylinder biturbo engine.
Efficient cooling of charge air, water and engine oil
For optimum power output even when outside temperatures are high, Mercedes-AMG uses indirect air/water intercooling. With optimum air and water flow, the intercoolers have a separate, two-stage low-temperature water circuit. The water-flow intercoolers ensure that the charge air compressed and heated to up to 140 degrees Celsius by the turbochargers is effectively cooled before entering the combustion chambers, and remains at a constant, low level of max. 25 degrees Celsius above the ambient temperature even under full load. A large radiator at the car's front end ensures controlled cooling of the water circulating in the low-temperature circuit. Extremely short charge-air ducting makes for optimum responsiveness.
The engine coolant is cooled on the particularly effective cross-flow principle, featuring two high-temperature radiators connected in parallel and a particularly efficient 1 kilowatt suction fan. A three-stage thermostat ensures rapid heating of the coolant.
Because the water pump is driven by a timing chain rather than the usual poly-V belt, a simplified belt drive system is used with less clamping force. This results in less loss of drive power. With a rated flow of 420 litres, the water pump conveys the equivalent of more than two full bathtubs per minute.
An external engine oil cooler in the front apron of the Mercedes-AMG GT helps with heat management for the V8 engine. It is located in the front apron for aerodynamic efficiency. A two-stage, controlled oil pump circulates the engine oil. This varies the flow rate depending on load and engine speed requirement, thereby benefiting fuel economy. At high engine speeds more than 1.0 litre of engine oil per second flows through the oil lines and ducts. To save on weight numerous oil and water lines are made of aluminium.
Sophisticated solutions are also deployed on the engine's periphery:
  • Separate passive air duct for the turbochargers subject to high levels of thermal stress
  • Dynamic engine and transmission mounts for excellent lateral dynamic performance and a high level of comfort (optional)
  • Auxiliary units efficiently powered by two short, low-friction belts with four grooves. Intelligent positioning of auxiliary units virtually neutralises belt forces on the crankshaft.
  • Two-mass flywheel with centrifugal pendulum prevents torsional vibration on the drive line for a smooth ride.
  • ECO start/stop function and alternator management to save fuel.
High-tech test benches for engines with over 470 kW
There are nine high-tech test stations in Affalterbach on which AMG engines with an output exceeding 470 kW and more than 1000 Nm undergo dynamic testing. These test facilities enable a very wide range of road and environmental conditions to be simulated to reproduce any conceivable type of operational scenario. Cold or hot starting, mountain passes, stop-and-go traffic or fast laps on the North Loop of the Nürburgring – the engines are required to give their utmost. Even different intake air temperatures and densities can be computer controlled.
Function and endurance benchtesting for the highest quality
The goal of the detailed bench tests is to verify the performance of all engine components, including the peripheral units. All measurement data for the engines examined are systematically compared and evaluated using reproducible test methods. The functional tests are accompanied by endurance testing. To ensure the very highest quality standards over their entire operating life, new AMG engines are required to undergo several thousand hours of endurance testing.
Extensive trials in every climatic zone on earth
Simultaneously the test engines undergo intensive testing in practical trials. The standardised test programme at Mercedes-AMG includes all climatic zones and route profiles, from the icy cold of northern Sweden to the merciless heat of Death Valley (USA), from fast laps on the North Loop of the Nürburgring and high-speed circuits in Nardo (Italy) and Papenburg to stop-and-go city traffic during rush hour. This programme makes the very highest demands on the day-to-day practicality, reliability and long-term durability of new engine generations.
A tradition of hand-built excellence: "one man, one engine"
The AMG 4.0-litre V8 biturbo engine is produced in Affalterbach according to the "one man, one engine" principle. In the AMG engine shop, highly qualified technicians assemble the high-performance engines by hand according to the strictest quality standards. The technician's signature on the AMG engine plate attests to this exclusive type of engine production. It guarantees the highest quality and technology transfer from motorsport – covering the spectrum from Formula 1 through DTM to customer racing activities.
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