Welcome to Pop The Hood, a weekly autoMedia.com feature that examines the hottest new models on the market and the things that set them apart from the competition. In the past, we’ve examined weight savings in the Scion FR-S and the intimidating power of the Ford Shelby GT500. Today, we’ll discuss the impressive efficiency of the N55 engine in the BMW 335i.
The 3.0-liter Inline-6 engine (codenamed the N55) has been around since it debuted in the 2009 5-Series Gran Turismo, but it truly comes to life in the 2012 BMW 335i and makes its case as one of the greatest powerplants ever designed by the vaunted Munich minds. Here are five things you need to know about the N55.
1. Twin Scroll Turbocharger: BMW opted to use a single, twin-scroll turbocharger in the N55 engine rather than the twin turbos in the previous N54. They’ve coined it the TwinPower Turbo, a design that is essentially the same as a twin-turbo but in a single housing. The result is higher low-end torque as well as higher power output at low rpm.
2. Valvetronic: The N55 debuts another BMW innovation, a direct injection fuel system called Valvetronic. Basically, an electric stepper motor is built into the cylinder head and controls the lift of each individual intake valve on every cylinder. Your engine breathes more freely, your performance improves and it sips less fuel. It’s like a BreatheRight strip for your N55.
3. Peak Torque Earlier in Powerband: The N55 produced the same 300 horsepower and 300 lb.-ft. of torque as the N54, but it’s available quicker than ever before. Peake torque is now available at 1,200rpm rather than 1,400rpm, so you get a better response out of that engine that you just plopped down $36,650 for. It takes the 335i just 2.25 seconds to transition from low load to full load. In the N54, it took 2.75 seconds.
4. Better MPG: Notice a theme in our Pop The Hood features? Maybe we are fans of fuel efficiency, and maybe automakers are just making a real commitment to reducing consumption. Either way, the story here is that it’s certainly possible to build an exciting vehicle with better performance and better fuel usage. The 2012 BMW 335i is rated at 19/28mpg, an 8-percent improvement over the N54 engine.
5. Cylinder-Bank Comprehensive Manifold (CCM): It’s really amazing the lengths that BMW will go to improve an already impressive engine. The N54 was fantastic, but one of the reasons that they switched to a twin-scroll turbocharger in the N55 is that the previous twin-turbo suffered from turbo lag. Not much, mind you, but it did. This doesn’t fly at BMW. So they created CCM, a single-piece unit that minimizes charge cycles and has essentially eliminated turbo lag completely.