Mercedes-Benz M-Class Adds V8-Powered ML550 For 2008

V8-Powered ML550 Joins M-Class SUV Family

DETROIT, MI – The 2008 M-Class line features the ML550 – a new 382-horsepower V8-powered model that replaces the ML500. Providing a 26 percent boost in power, the new ML550 joins three very different models – the fuel-efficient ML320 CDI diesel, the popular ML350 and the high-performance ML63 AMG.

AMG Styling for the ML550

For 2008, the ML550 receives AMG styling, including unique front and rear bumpers, 19-inch wheels with all-season tires, a power glass sunroof and running boards – all as standard equipment, while the 2008-model ML350 and ML320 CDI come standard with 19” wheels, the Appearance Package (chrome accents, blue glass) and power sunroof.

The M-Class line features a sleek exterior with a unit body platform and four-wheel independent suspension that deliver impressive on-road driving performance and comfort. Useful technology abounds in the M-Class, including a standard seven-speed automatic transmission, full-time four-wheel-drive, four-wheel traction control and optional features such as height-adjustable AIRMATIC air suspension.

All-Aluminum 5.5-Liter V8 Power

The new ML550 is powered by a 5.5-liter all-aluminum V8 producing 382 hp and 391 foot-pounds or torque, with maximum torque available from 2,800 to 4,800 rpm, providing impressive engine response over a broader RPM range.

Not only does the 5.5-liter V8 come with four valves per cylinder, but the high-tech engine also features double overhead camshafts in each cylinder bank and variable valve timing for both the intake and exhaust valves. The new engine also has “tumble flaps” in the intake for better fuel economy and an electronically controlled two-stage intake manifold that broadens the power curve.

Variable Valve Timing and Tumble Flaps Improve Fuel Efficiency

Valve timing is automatically adjusted by electro-hydraulic vane-type adjusters on the end of each camshaft. At partial throttle, the adjusters keep the exhaust valves open as the intake valves are opening, using this valve overlap for internal exhaust gas recirculation, reducing exhaust emissions and improving fuel economy. Approaching full throttle, the camshaft adjustment optimizes valve timing for maximum power.

Tumble flaps in the intake passages near the combustion chamber pivot open under partial load, improving combustion by creating additional turbulence around the intake valve and in the combustion chamber. During higher engine loads such as full throttle, the tumble flaps are completely recessed in the wall of the intake manifold. While better combustion helps improve engine torque, the primary purpose of the tumble flaps is to further increase fuel economy, and tests show that the tumble flaps indeed boost gas mileage by nearly two percent.

While variable valve timing gets a lot of credit for the engine’s unusually broad torque curve, a two-stage magnesium intake manifold plays a key role as well. Below engine speeds of 3,500 rpm a set of flaps in the manifold close off short intake passages, forcing intake air to take a much longer route into the engine. This creates pressure waves that help the intake process and improve torque. At higher engine speeds the flaps open, and intake air flows the shortest distance into the engine, helping to make more horsepower.

Source: Daimler