The engine in the 335d and X5 xDrive35d (internally recognized as the M57N2) has been modified extensively for US consumption.
Most enthusiasts are familiar with the urea injection system (Diesel Emissions Fluid) to combat NOx emissions for the US market but it is the other changes for the that are not as well known. Here are many of the changes.
Wrist pin locations are offset- moved towards cylinder wall to create less rock in the power stroke and decrease noise. The pins have also been tweaked, and obviously the pistons are different.
Additional cast reinforcement on the bottom of the engine crank case. It covers 4 of the main bearings to increase stiffness, decrease vibration and reduce noise.
Noise reduction panel added under the engine.
The crank case ventilation system is heated and monitored (improved emissions).
Torque converter has twin axial spring dampers to smooth flow of power when transmission coupling is locked up.
Electronic ceramic heater for increased heat during cold weather for the occupants in the vehicle.
These changes are for improved emissions, decreased noise/vibrations and improve creature comforts. None of these items are truly necessary but they have helped make the appeal of diesel greater for the US market, with an additional price.
Original content from BimmerFile.com
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