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      08-07-2013, 01:30 AM   #37
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Drives: 2012 AW/CR 135i Msport
Join Date: Nov 2011
Location: KC, MO

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Originally Posted by Rob@RBTurbo View Post
I kind of agree with you. After 550hp is where I have a feeling things may get sketchy. Cast crank and cast rods are not a great combo.
As pointed out on another forum im on, citing the training manual. They feel this could help out with the shortcomings of cast crack and rods.

The crankshaft of the N55 is of lightweight design, at 20.3 kg itís approximately 3 kg
lighter than the crankshaft in the N54 engine.
The crankshaft is made from cast iron (GGG70). The counterweights are arranged asymmetrically.
There is no incremental wheel installed on the crankshaft. The timing chains
are mounted by means of an M18 central bolt.

The size of the connecting rod of the N55 engine is 144.35 mm. A new feature is the
specially formed hole in the small end of the connecting rod. This formed hole is
machined wider on the lower edges of the wrist pin bushing/bore. This design evenly
distributes the force acting on the wrist pin over the entire surface of the rod bushing and
reduces the load at the edges, as the piston is forced downward on the power stroke.
2013 BMW X3 xdrive35i ///MSport Deep Sea Blue / Black Nevada Leather

2012 BMW 135i ///MSport Alpine White / Coral Red Leather
JB4 Stage 2 ISO | BMS Intake | ER Charge Pipe | AR Downpipe