AMG-Designed Engine: One Of The Most Powerful V8s On The Planet

An entire family of high-performance AMG models are powered by the first engine developed entirely by AMG.  The naturally aspirated 6.3-liter V8 produces between 451 and 518 horsepower, depending on the model.  The V8-powered AMG model lineup featuring this engine includes the C63 AMG, E63 AMG and S63 AMG sedans; the CL63 AMG and CLS63 AMG coupes; the ML63 AMG sport utility vehicle and the SL63 AMG roadster.

AMG Racing Success Spawns High-Power Production Engine

One of the most powerful naturally aspirated production V8s ever, the M156 engine boasts a wealth of exciting features derived from AMG's highly successful racing efforts.  Built almost completely from a high-strength silicon-aluminum alloy, the 6.3-liter features four valves per cylinder, variable valve timing, bucket followers (rather than rocker arms) and a variable-length intake manifold.

Crankcase Bedplate Instead of Main Bearing Caps

For greater strength and reliability, the AMG engine uses a rigid one-piece bedplate at the bottom of the engine block instead of individual main bearing caps that can distort or loosen at high RPM.  With cast-in steel inserts for greater strength, the aluminum bedplate essentially sandwiches the crankshaft between two sections of the sturdy engine block.

A Racing Crankshaft

Made of high-quality 42CrMo4V forged steel alloy, a finely balanced crankshaft with six counterweights spins in five main crankshaft bearings.  The crankshaft counterweights feature heavy metal plugs - a detail usually found only in racing engines - which means the counter-weights can be much smaller, increasing power by reducing rotational inertia and oil drag.

Each forged connecting rod is precisely "cracked" with the help of a laser beam, so the irregular fracture contributes to its strength when the two halves are clamped around the crankshaft.  The connecting rods and lightweight pistons are matched for extremely close weight tolerances that contribute to smooth running at high speeds.  Small nozzles in the engine block spray cooling oil onto the underside of each piston crown.

TWAS Twin-Wire-Arc-Sprayed Cylinder Bores

The cylinder bores feature a twin-wire-arc-sprayed (TWAS) coating, an innovative process that results in impressively low friction and running surfaces that are twice as hard as conventional cast-iron cylinders.  The engine block and cylinder heads are made of cast aluminum silicon alloys (AlSi7 and AlSi17), which represent the state of the art in terms of strength, light weight and thermal benefits.  First, a high-pressure water jet roughens the cylinder bores.  Then two electrode wires and an atomizing gas form plasma under high voltage.  In essence, the atomizing gas sprays molten metal from the wires onto the cylinder walls, where it solidifies, forming an extremely hard coating. A honing process finishes the cylinder bores, exposing micro-pores in the hard coating that will retain oil and ensure good lubrication of the pistons and piston rings.

Vertical Intake and Exhaust Ports

Adapted from racing designs, air passing through the engine follows a straight line down through the intake manifold into its hemispherical combustion chambers and out the exhaust passages.  A patented dual-length intake manifold is part of the vertical intake and exhaust system.  The engine shares no parts with Mercedes-Benz V8 engines.

Operated by the Bosch 9.7 engine management system, two electrically-operated internal flaps control air flow through a variable-length magnesium manifold.  At relatively low engine speeds, intake air flows through long runners, which helps to maximize engine torque.  At higher engine speeds, the flaps allow intake air to flow through shorter pipes for maximum high-speed horsepower.  Two integral hot film air mass sensors behind the air cleaners provide the engine electronics with information about the density and temperature of the incoming air.

"Bucket" Followers Instead of Rocker Arms

The AMG-designed engine also features a sophisticated valve train, also adapted from the AMG racing engines.  Each intake valve is 40 millimeters in diameter, while exhaust valves measure 34 mm.  Twin overhead camshafts in each cylinder bank open the 32 valves via bucket-type followers.  In other words, instead of rocker arms, the cam lobes sweep across the flat tops of the buckets, which sit directly on top of the valve stems.  This space-saving design provides a very stiff valve train that allows for large valve openings and dependable high-speed operation for maximum horsepower and torque.  However, in contrast to racing engines, each bucket incorporates a hydraulic lifter that automatically maintains valve clearance, which allows for long service intervals and low costs.

Variable Valve Timing

The AMG V8 makes use of variable intake and exhaust valve timing to maximize efficiency and torque over a wide RPM range.  Valve timing can be automatically adjusted within a range of 40 degrees using electro-hydraulic vane-type adjusters on each camshaft. 

At part throttle, the valve timing adjuster keeps the exhaust valves open as the intake valves are opening, using this valve overlap to create internal exhaust gas recirculation, reducing exhaust emissions and improving fuel economy.  However, approaching full throttle, the camshaft adjustment optimizes valve timing for maximum power.  The intake cams are driven by a double chain from the crankshaft, and small gears on the intake cams drive the exhaust camshafts.

AMG's Supercharged V8

Based on earlier engine architecture, a supercharged V8 powers the G55 AMG - with a dual side pipe exhaust system that produces 500 horsepower.  A normally aspirated 355-hp version of this 5,439-cc V8 is used in the SLK55 AMG model.  For these models, the AMG V8 engine makes easy work of the 0-60 mph test track sprint in 4.9 seconds for the SLK and 5.4 seconds for the G55 AMG.

A Powerful Kompressor Between Cylinder Banks

The AMG Kompressor V8 in the G55 AMG makes impressive power, due in large part to a belt-driven "Lysholm" or screw-type supercharger that develops about 30 percent more intake pressure than other comparable supercharging systems.  Each Teflon-coated rotor spins at a maximum of over 23,000 rpm and, in doing so, can push up to 4,000 pounds of air per hour into the engine's combustion chambers (at 70 degrees F, sea level).  The maximum boost pressure is 0.8 bar or 11.6 pounds per square inch.

The engine management unit determines whether to engage the supercharger depending on the engine speed and load.  Under light loads, when the throttle is open only slightly, the Kompressor V8s operate purely as a naturally aspirated engine.  However, the supercharger goes into instant action when the driver accelerates.  Under 2,700 rpm, the supercharger runs only when the throttle is open and the engine is under load, but above 2,700 rpm, the supercharger is engaged full-time.  This nets many advantages - thermal efficiency, fuel consumption, noise and exhaust emissions.

The load- and rpm-dependent operation is carried out by an electromagnetic clutch that gets its signals directly from the fully electronic Bosch ME 2.8.1 engine management system.  The driver doesn't feel or hear the supercharger activation.  Torque build-up is extremely smooth, and the supercharged V8 engine shows its muscle evenly throughout the rpm range.

Compact Water-Cooled Intercooler

To improve efficiency even further, an intercooler sits between the cylinder banks, operating as an air-to-water heat exchanger, extracting heat from the compressed air and transferring it to the coolant.  A dedicated pump allows the water to flow through a special low-temperature cooler located between the air conditioning condenser and the radiator, and this system works independently of the primary coolant circuit for the engine.

In contrast with air-to-air systems - in which ignition timing and engine power must be reduced under high thermal load - this advanced water-to-air cooler enables the full output and torque of the supercharged V8s to be on tap at all times.  Also, an oil cooler is housed in the front apron.

The Sound of Power

Both types of V8 engines come with an exhaust system that's just as sophisticated as the rest of the car.  With the exception of the two exhaust manifolds, the complete exhaust systems of each Mercedes-AMG model have been designed specifically for that application.  All four catalytic converters feature thin-wall ceramic material, and large surface area inside the ceramic element ensures low exhaust back pressure, benefiting both performance and exhaust emissions.  The resulting sound emanating from the twin-oval AMG tailpipes is also distinctively throaty.

One Man, One Engine - Individual Hand Craftsmanship

Each new AMG engine is hand-assembled one at a time by an expert craftsman at Mercedes-AMG in Affalterbach, Germany.  Mercedes-AMG follows a philosophy of "one man, one engine," which means that a single technician - identified by the signature plate affixed to the engine - is responsible for the complete assembly of an AMG high-performance engine from start to finish. 

With the utmost care, the craftsman installs each and every part - from the crankshaft, connecting rods and pistons to the intake system, wiring harness and oil fill-up.  Each new engine is bench-tested to ensure consistent quality and maximum performance.

About AMG

AMG has been the high-performance subsidiary of Daimler AG since 1999 and is located near Stuttgart in the country village of Affalterbach, Germany.  AMG employs more than 600 specialists in development, production and administrative areas.  AMG develops each of its models, including the transmission, chassis, brakes, aerodynamics, interior and - most importantly - the engine. 

AMG engines are the product of a surprising combination of cutting-edge technology, computer-aided design and old-fashioned hand craftsmanship.  No automobile capable of eye-popping flat-out performance also displays such a docile nature in every-day driving.  Each engine is produced and tested at AMG's headquarters in Affalterbach, and AMG models are assembled at the main Mercedes-Benz vehicle manufacturing plants. 

With more than 50 percent of AMG sales, the U.S. is the top market for AMG worldwide.  While all Mercedes-Benz authorized dealers offer AMG products, about 25 U.S. dealerships serve as AMG Performance Centers, which include specially trained staff, uniquely branded point-of-sale materials and highly popular "AMG Performance Tour" weekend driving events.  AMG also offers track-based Driving Academy and AMG Challenge programs.

About Mercedes-Benz USA

Mercedes-Benz USA (MBUSA), headquartered in Montvale, New Jersey, is responsible for the sales, marketing and service of all Mercedes-Benz and Maybach products in the United States. For more than forty years, MBUSA has taken pride in providing superior quality luxury vehicles coupled with a commitment to outstanding customer support.   More information on MBUSA and its products can be found on the Internet at www.mbusa.com and www.maybachusa.com.

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