We presented you yesterday news that the upcoming 2012 Mercedes-Benz SLK55 AMG would receive a new naturally aspirated 5.5-liter V-8 engine with fuel saving cylinder deactivation technology. Well now comes the first official details and images of the new powerplant.
Mercedes-AMG has developed a new 5.5-litre V8 engine which combines powerful eight-cylinder performance with the decidedly economical fuel consumption of a four-cylinder. Unrivalled efficiency is achieved thanks to the AMG Cylinder Management cylinder shut-off system newly developed by Mercedes-AMG. This new technology exclusively developed by AMG is inspired by Formula 1 racing. In the eight-cylinder racing engines developing around 750 hp, cylinder shut-off is likewise used primarily to save fuel.
Fuel economy has been improved dramatically, even with peak output lifted to 415 horsepower and 398 pound-feet of torque, up from 355 horsepower and 376 pound-feet of the previous 5.4-liter V-8 that this engine replaces.
M157 V-8 engine, which is based on the existing twin-turbocharged, is making its way into more of AMG’s top-end models, this new ‘M152’ naturally aspirated unit is claimed to be 30 percent more fuel efficient than the one it replaces and is destined to be one of the last high-performance engines in Mercedes’ lineup without the aid of forced induction.
These two engines have many components and systems identical. Here we include the displacement, bore and stroke, the engine stop-start system, distance between cylinders and direct injection technology. However, unique to the M152 are its new intake air ducting, modified valve drive, new cylinder heads, custom oil supply system and optimized crankcase, and of course, the cylinder deactivation technology.
The driver is always informed by the symbols in the main instrument cluster whether cylinder shut-off is active, and whether the engine is currently running in four or eight-cylinder mode. Despite only running on four-cylinders, in this mode the engine still has a reasonable 170 pound-feet of torque on tap.
It seems that once the driver floors the throttle and the tacho passes the 3,600 rpm mark, the rest of the cylinders fire up in a process that takes no more than 30 milliseconds.
Beside all these, the engine is also fitted with a sports exhaust system with integrated flaps. This is a pretty cool system because it allows the car to run relatively quiet at low speeds and much louder once the driver dials up the revs. Each of the two rear silencers has a flap which is adjusted depending on the driver’s accelerator input and the engine speed.
These two flaps remain closed at low loads and engine speeds below 2,000 rpm. This causes the exhaust gases to cover a longer distance and flow through an additional damping element, so that the engine sound is subdued. When the driver accelerates, the flaps open at an angle of 15, then 30 and up to 50 degrees so that some of the exhaust gases cover a shorter distance. Under full load at higher engine speeds, both flaps are fully opened.
Official EPA figures are yet to be released.
Until this motor debut in the 2012 Mercedes-Benz SLK55 AMG at this September’s 2011 Frankfurt Auto Show, you can chec-out the gallery below of the latest 2012 Mercedes-Benz SLK.
Source: Motorauthority
