BMW 135i with N54/DCT

The short answer is; we don ‘t know. But let ‘s take a look at what we know. Last weekend we exclusively broke the news that the 135i was not only getting the DCT 7 speed dual clutch transmission but also the N55 inline six turbo. More specifically BMW is replacing the N54 dual turbo with the N55 single turbo twin-scroll. It ‘s great news for fans of the 1 Series and DCT technology but what about that engine change?

As you may have heard from our interview with Martin Birkmann, the switch to the N55 is all about efficiency. And on paper it makes sense with identical numbers in regards power and torque. But what about the N54 ‘s power being under-reported? We had heard for years from automotive magazines and websites that dynoed the engine that the N54 was actually putting out well over 320 hp (and sometimes much more). While no one yet has dynoed an N55 we ‘d guess that we will not see those kind of numbers from the single turbo twin-scroll set-up. What does all this mean? While on paper the N55 is a match for the N54, in the real world we can ‘t help but wonder if the 2011 135i and the 335i didn ‘t just lose a little power versus the 2010 models.

BMW 135i with N55/DCT

Anything lost (even unofficially) BMW will be giving back in the form of the forthcoming BMW Performance engine kit for the N55. Engineers are currently fine-tuning the kit and expect to have it available sometime in the latter half of the year. However beyond that option, BMWfirmly believes that the N55 will be “tuner proof “. They expect that tuning the N55 will be infinitely harder to do as compared with the N54. So while the N55 has the efficiency, for the enthusiast it clearly has some downsides. If you take away the N54 ‘s oil cooler issues it ‘s been a fantastic engine for BMW and the enthusiast market. It has fantastic power and torque while delivering respectable fuel figures.

Will the N54 equipped 135i and 335i be the more coveted cars in the years ahead? No doubt some will think so. However if true, we ‘d guess that would only be the case for the enthusiast market. The N55 will surely continue to serve multiple BMW models well while being noticeably more efficient. It ‘s just a shame that we may have lost some of that unadvertised oomph that the N54 was known for.