Another important thing to note is that we chose to publish each engine's LOWEST output to ensure we didn't publish a nonrepeatable number. The first N54's actual power peaks were 276, 276, 280, and 283 hp. The second's were 285, 282, and 287 hp. The third's were 276 and 277 hp. Such minimal variation from run to run shows that the N54 is a very consistent engine in addition to being a very powerful one.
So it's no wonder we jumped at the opportunity to be the first to publish dyno results for a manual-transmission 2011 335i coupe. (We've seen dyno results for a 335i with a twin-clutch transmission, but for a true apples-to-apples comparison, we wanted a car with the same transmission. The DCT could experience greater loss due to its hydraulic pump and different gear ratios.)
The new engine, the N55, is different from the N54 in that it uses only one larger turbocharger in place of the N54's two smaller turbos. To keep lag to a minimum, BMW used a twin-scroll turbo and its Valvetronic throttle-less, variable-valve-lift system. On the street, after driving N54 and N55 cars back to back, it's definitely safe to say that the N55 suffers from even less turbo lag than the N54 did. And that engine set the benchmark.
BMW's quoted output for the N55 remains 300 hp and 300 lb-ft, which raises a question: what if the N55 actually does only make 300 hp? And, given the simultaneous appearance of a 335is (which uses an even more potent, 320-hp version of the N54) we couldn't help but wonder: what if the 335is didn't actually make any more power than the old, underrated 335i?
There's only one way to find out, right? Call the dyno shop.
To answer the questions quickly: BMW isn't hiding anything. The 335is put down 293 hp and 343 lb-ft, beating every previous N54 we've tested by a big margin. And if you look at the torque curve, the midrange overboost function BMW promised (rated at 369 lb-ft) is definitely alive and well. The 335is engine is, like the original N54, probably still underrated.