Quote:
Originally Posted by swamp2
The displacement of the new engine is a matter of debate. There is also some debate on what is forged in the N54 and N55. Best I can tell is that the N54 had a forged crank whereas the N55 has a cast one. However, the newer cast design was actually significantly lighter (3 kg). The resulting change was likely driven by a cost cutting exercise. Some claim the N54 also had forged Mahle pistons but others say not. I think the con rods in both are cast based on these pictures. |
I would like to think BMW will use displacement to differentiate the S55(??) from N55, and using a specific to S55 longer stroke forged crank would be a sensible way to achieve that.
Cast cranks have made a bit of a resurgence, think it's down to a new process that reduces the porosity.