Autoweek's BMW N20 Engine Review -- four cylinders, more power

[GregW / Oregon]

From Autoweek.com, 2/18/11

More power, greater torque, reduced fuel consumption, lower tailpipe emissions and less weight--but better? Before driving the BMW X1 xDrive28i, the first model to feature the German carmaker's new turbocharged 2.0-liter four-cylinder gasoline engine, we weren't so sure.

The new engine, known as the N20 and set to lead a return of four-cylinder BMW models to North America for the first time since 1998, has been conceived to (indirectly) replace the company's long-running naturally aspirated 3.0-liter inline six-cylinder. It's part of an ongoing downsizing program at the center of BMW's EfficientDynamics initiative.

The new four-cylinder follows the blueprint set by BMW's most recent turbocharged 3.0-liter inline six-cylinder, the N55. It boasts the same 3.5-inch bore center spacing and runs a twin-scroll turbocharger (albeit from Mitsubishi, not Borg Warner), Valvetronic variable valve timing, a Vanos camshaft control system and the latest high-pressure direct-injection system from Bosch. At 317.5 pounds, the engine weighs about 40 pounds less than the old naturally aspirated six-cylinder.

The BMW X1 crossover is the first vehicle to use the N20 turbocharged engine. First impressions reveal the N20 to be up to the job. With peak power arriving 1,600 rpm earlier and peak torque arriving 1,350 rpm earlier than with the six-cylinder, the N20 doesn't have to be worked hard before delivering its best.

In everyday driving, the N20 is noticeably more responsive, although its sound is nowhere near as alluring as that of the engine it replaces. BMW says that will be fixed on certain models, including on an updated Z4 sDrive28i, with the addition of an electronic sound generator.

At 240 hp, the N20 develops 10 hp more than BMW's 3.0-liter inline-six in North America. It is terrifically refined and always feels urgent, with 260 lb-ft of torque on tap at 1,250 rpm. The power delivery is uncannily like that of a modern-day diesel, with particularly strong low-end attributes and impressive flexibility across a wide range of revs.

The six-speed manual version of the new X1 xDrive28i is claimed to reach 62 mph in 6.1 seconds, hit a top speed at 149 mph and boast a 50-mph-to-75-mph fourth-gear split at 6.0 seconds. By comparison, the current X1 xDrive28i sold in Europe, which uses a 258-hp version of BMW's 3.0-liter inline-six, posts figures of 6.8 seconds, 143 mph and 6.1 seconds, respectively.

Power builds in a smooth, free revving fashion without any hint of turbocharger lag. Work the N20 hard, and it revs happily to 7,000 rpm, although like most modern direct-injection units, there's a distinct lack of engine braking on a trailing throttle. The engine's powerful electronics package ensures maximum coasting potential is achieved by allowing the revs to fall away gradually.

Combining the N20 with BMW's familiar EfficientDynamics package-brake-energy regeneration, stop/start and an on-demand water pump--results in a 16 percent improvement over the inline-six in the combined European consumption cycle at 29.8 mpg (U.S.).

So the N20 is pleasing to drive and highly efficient. But, as it stands now, it's not as aurally entertaining nor as engaging as the six-cylinder it will eventually replace. Not yet, anyway. The potential is there, though.

http://www.autoweek.com/article/2011...NEWS/110219868

[dmboone25]

Great info--sounds like a winner.

What is a sound generator? Does it artificially replicate the lost sound of the I6?

[positiveions]

interesting. I wish this engine was around during the E30 reign. or can we slap one in an E30 ? Future Project?

[rodgerdodger]

NICE!

[GregW / Oregon]

Originally Posted by eatrach73

interesting. I wish this engine was around during the E30 reign. or can we slap one in an E30 ? Future Project?

They can make the engine sound like almost anything with electronics - how about a flat plane crank V12?

[PJPHughes]

BMW needs to be honest....call it an xDrive20i...that's what it is!! What's with the mislabeling of engine size.

Granted my 335d should be a 330ttd or 330dt2....LOL

[Thud]

Sound generator? Pretty effing weak if you ask me. I'd rather just hear the motor.

Unless they can make it sound like a jet engine. That would be cool.

[m-technik]

Originally Posted by dmboone25

What is a sound generator? Does it artificially replicate the lost sound of the I6?

I thought they were only gonna use those on ev's to alert people of their presence. Use of them to "better" the sound of an engine is beyond tacky.

[marvinp]

Everything about the engine seems good, but electronic sound generator on some models? That's kinda lame.

[r53s65e90]

Nice engine...

...with ring tones?? Why not make it sound like a V8? Will they offer downloadable engine tones too?

[penny]

[CaliE90]

Originally Posted by penny

that sounds like a car thats in a video game

[Wolf]

its obviously a great engine... i mean 4 cylinder is doing 240 hp is great... but i think the more power they give to a smaller engine, the more huge problems the engine will suffer from... and a sound generator is tacky

[vladberca]

The sound generator must be optional.... Who would buy one?

[Undies]

imagine the possibilities of all the ricers that mod the sounds generation part of the car lol

[just4kickz]

Originally Posted by penny

i'm sure they use sound modules for safety as well. those electronic cars or hybrid cars running only on battery don't make very much noise...

but as far as using it on a bmw... really? no thanks. i'd rather know what the car actually sounds like.

[takashin]

i wonder what the chipped hp is....

[iveman89]

Man If were going to be using improvised exhaust sounds im going with this

[marcel b]

the previous Z4 3.0 had a soundgenerator (non-electronic), so does the Golf GTI. Let's see what they come up with.

[Dennis911]

I stopped reading after "Electronic sound generator". I do not care which cars have/had one, nor do I ever want to see such an artificially improving or generating gadget in any car, let alone a BMW. It is a rediculous and pathetic measure to fake something that just is not there: sound.
The automobile equivalent to stuffing socks in your underwear.

[Canexican]

Sound generator? You kidding me? Just throw on an open element air filter and I guarantee you it will sound nice. I guess they feel BMW owners are not progressive whatsoever and will almost certainly want to live in the past with their prior I6's. It's sad that even BMW corporate doesn't think I4T's sound good. Give me a break.

Love that it is going to come in a manual though. At least they got that part right.

[Weaselboy]

Originally Posted by Canexican

Sound generator? You kidding me?

I'm having flashbacks of my old 3-speed bicycle from childhood with a playing card clothes pinned near a wheel spoke. Good times.