BMWUSA Model Year 2011 Fall Update

Packaging is better for the new engine A further advantage of turbocharging is that this is the most weight-efficient method to boost engine power and performance. The N55 turbocharged inline-6 weighs approximately 150 lbs. less than an equally powerful eight-cylinder engine displacing 4.0 liters. This lower weight means a significant advantage not only in fuel economy, but also in balancing the car’s weight distribution.

Using Valvetronic for the first time on a turbocharged inline-6 allows the engine to “inhale” air for combustion with virtually no delay and with reduced pumping losses. As a result, the engine makes power more quickly than ever before, and this is proven by the N55’s ability to reach peak torque at 1200rpm, 200rpm earlier than its twin-turbo predecessor [N54].

Packaging is better for the new engine, as the BMW Digital Motor Electronics (DME) control unit is now mounted directly to the engine, shortening the required wiring harness length and providing more efficient cooling to the DME through the use of intake air. Furthermore, using a single turbocharger means only a single exhaust stream must find its way to the catalytic converter, so only a single catalytic converter is used on the new engine. The single catalytic converter can be activated more quickly at cold start than the preceding twin-catalyst configuration, so the new engine has a cleaner cold start emissions signature than its predecessor. The new “N55” engine will be installed in the 135i Coupe and Convertible, the 335i Sedan, Coupe and Convertible (excludes 335is models), the new 535i Sedan when it arrives this summer, the 535i Gran Turismo arriving this spring and finally, the X5 xDrive35i and X6 xDrive35i Sports Activity Vehicles? starting with April production.