ASAP Car Review: First Drive - 2011 BMW 335i N55 Motor Review

This particular vehicle is one that I am familiar with very well as I have had the privilege of owning it. Sit back, relax and enjoy my review of one of the world's most renowned sports sedans continuing its presence as the Ultimate Driving Machine as numerous competitors try to catch up.

The Engine

My 2011 335i comes with a new generation of turbocharged engine from BMW, the N55 which is also known as the successor of the widely popular and successful N54. Models before 2011 had the numerous turbocharged engine of the year award winning Twin Turbo N54, a 3.0L Straight Six cylinder monster which came from the factory with 300 horsepower and 300 pound-feet of torque. For 2011, BMW decided to make the switch to the newer twin scroll single turbo N55 motor. One might ask; "What was the need for the change?", and at first glance, we would agree; but after driving the new motor for a week or so, we could see the logic behind BMW's thinking. The new motor retains 300 hp and 300 pound-feet of torque but gains a noticeable 10% improvement in fuel economy over the N54 and has that massive torque available from as low as 1200 RPM when compared to the N54's 1400 RPM. The engine is incredibly smooth and has one of the sexiest exhaust sounds on a stock car that I have personally ever heard. Facts and figures aside, having driven both the N54 and N55 motor, my impressions when comparing the two tend to conflict. What I truly loved about the older N54 motor was its almost NA (Naturally Aspirated) big V8 feel, the engine appeared to have no lag at all and power delivery was instantaneous across the rev range. The newer N55 motor does not seem as urgent in the mid range but does appear to have more of kick down low, especially below 3000 RPM, this could be the result of BMW's decision to use Valvetronic in this new motor, a system of controlling the throttle blade that is designed for maximum fuel efficiency.

The Newer Single Turbo BMW N55 (MY 2011 +)

The newer BMW N55 motor incorporates one of BMW's first applications of Valvetronic in a turbocharged gasoline platform. This provides for greater fuel efficiency and improved throttle responsiveness.

BMW N54 (2007-2010 Model Year)

Tunability

The big question that everyone is wondering about is the tune ability (getting the most power in aftermarket tunes) of both motors. As everyone knows, the BMW N54 was significantly underrated from the factor, with several independent dyno tests showing that the engine was closer to 320 hp at the crank. Most dynoed between 265 and 275 wheel horsepower. When I took my bone stock N55 motor 335i with Steptronic Automatic Transmission to a dynojet independent facility, I was able to squeeze 270 wheel horsepower out of it, I'll be it with a slightly different power curve. When comparing both of the power curves of the older and newer motor, it appeared to me that the older motor's turbos did not run out of steam as quickly as the newer motor's single compressor had. This is rather ironic as Automobile Magazine stated in an independent test of the N54 vs the N55; that the N55 had a stronger top end. Well in any case, on a bone stock car, you can be the judge for yourself when I did an independent test on a lone Mexican road to find out about this "Top End" claim;

Please remember, that the above video test was done on a bone stock car on not the best of road conditions but I think most can agree that it gets up to 160 Miles per hour pretty quickly. Now what happens when that bone stock 270 wheel horsepower motor is ECU tuned to 340 wheel horsepower?

Thanks to the Vishnu Procede, I was one of the first people in the country to have an N55 motor tuned and it was quite an experience. Unfortunately for now, the N55 motor is limited to only 340 wheel horspower as there are very few bolt-on parts available for the vehicle. The previous generation N54 motor has already hit 440 wheel horsepower with full bolt ons and a meth kit running at close to 16 psi, will the N55 be able to do the same?? We shall she...

A few pictures for your enjoyment;