Quote:
Originally Posted by atomic837
As I still drive my 2009 135i (N54 engine) alongside my 2017 M2 (N55), I have the ability to do direct comparisons.
As it pertains to turbo lag in these cars, when I first picked up my M2, my initial perception was that it had significantly more lag than my 135i. From stomping on the throttle to full thrust, it seemed like a full second. This is irrespective of the driving mode it is in. Point blank, the 135i still feels like it is more eager to get up and go. It taps out in the high RPMs, and the M2 at full boost is a faster car, but the power responsiveness is slower.
Over the past few months something donned on me.... Maybe it's not the turbo lag that I'm feeling between the two cars as much as the raw NA power curve. My hunch is that the N54 engine, off turbo, has far more grunt than the N55 does. The extra grunt of the 135i "covers up" the turbo lag to full boost, providing for a very responsive driving experience, especially around town. Likewise, the M2 and its N55 engine really requires its turbo to make it a formidable engine... So in that initial accelerator press, the lack of its raw NA power is very noticeable to me (comparatively speaking).
Can anyone with experience in these two engines concur? Perhaps someone with both a 1M and an M2? I do recall discussion back in 2010 that the N55 was a bit lacking compared to its predecessor, favoring efficiency over power and responsiveness.
Would be interested to hear educated opinions on this.
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My educated
guess is because the 135I motor has twin turbos and the M2 has a single turbo, the twin turbo arrangement has a small turbo that spools quickly and a larger turbo for additional power. The single turbo in the M2 is larger than the smaller turbo in the 135I which takes a slightly longer time to spool up. Also, the M2 is 150 lbs. heavier.