Mercedes-Benz has announced it will stick to natural aspiration when it unveils the all-new SLK 55 AMG at the 2011 Frankfurt International Motor Show this September. The engine is the 5.5-litre V8 but with no turbo or superchargers in sight, quite a surprise to those who expected either the new 4.7-litre twin turbo or a smaller 3.5-litre turbo to emerge.
Nevertheless, this is a powerful 5461 cc motor codenamed M152, that weighs 187kg dry and produces 310kW at 6800 rpm and 540Nm of torque at 4500rpm, all sent to the rear wheels. No transmission details were released, but it is probable that a 7-speed automatic will be the favourite choice. As usual, four chromed tailpipe - two on each side - will tell us exactly what we’ll be dealing with here.
Mercedes-Benz began developing this engine in 2008 and has applied a system they called AMG Cylinder Management which shuts off four of the eight cylinders when they are not needed, in order to save fuel. It is a similar technology employed by Chrysler several years ago in their HEMI engines. The switch is said to take place in 30 milliseconds at 3,600 rpm, and is therefore imperceptible. In the end Merc claims an average of 8.5 litres per 100km, quite exceptional for the size and performance.