2011 New York Auto Show: BMW's N20 I4 Engine

It will take premium fuel like Audis 2.0T I cant wait to replace my 328i sport sedan with a 328i new body style an this motor. I love my inline 6 smoothness and feel but after a little work on this motor you will easily see 300hp and 300tq. I have 2 years left on my 328i lease so this is perfect timing. I hope they put this in the X3 to compete with the 2.0T Q5 because it will get better mileage and perform better. BMW is doing all the right things.

Also yellow on the Z4 looks great

Will it requre premium or just "reccmend" it? If American and Asian can do small turbo motors with big numbers on 87 why cant the Germans?

@body - no BMW engine requests 87 octane. Get over it. The incessant illogical braying from people about premium v. regular, I hoped, would die down as gas crested $4. Yet I still hear bellyaching about it as if it's egregious. Please...when gas was $1 a gallon I bought the argument but now...now it seems like just a rallying point for the cheap to complain about.

The whole key for me will be the power curve; if it acts like a diesel, I'll be less than impressed.

"@body - no BMW engine requests 87 octane. Get over it. The incessant illogical braying from people about premium v. regular, I hoped, would die down as gas crested $4"

How is asking a simple question "braying" ? Your defensiveness over the question is strange. If the Germans cant do it then they must not be as good at engineering as they, and their fans say they are.

It just appears to be laziness. it seems to me. There is nothing wrong with being frugal, even in an expensive car.

It's like a diesel. Torque peak @ 1250 (impressive). Power @ 5000 (yuck). No point in revs anymore. Will make it fast for sure. But not so much 'fun' (to people like me that like to wind it out).

And for those comparing it to Asian/American motors (and complaining) re: premium/regular. Be mindful that the German motors generally make their power/torque @ lower RPM. The aggressive tuning to do so generally requires premium. So it's not apples-to-apples. And frankly? Germans tend to underestimate their power. Those Hyundai motors? They seem slightly overrated (The Sonata has a better power-to-weight ratio than everything it its class -- and its not the quickest car). Just sayin'. GM (to their credit) is one of the only companies that uses SAE certification for their power production (Honda and Toyota are the other two that I can think of). Everyone else just follows whatever they've always done. The Germans sandbag, and SOME of the Asians tend to overestimate.

"The aggressive tuning to do so generally requires premium. "

Finally and answer! Thanks! That makes some sense. As for the ratings/under/over that is really not an issue. Every car company has a choice as to what to say an engine is rated for. That is what we have to compare with so that is what we use.

@body - being frugal while buying a car with a luxo badge (itself, mostly posturing according to most people) is kinda illogical, no? If someone is that concerned with an extra $150 a year in gas, then maybe wait another paycheck or two to save up for the gas price difference over the next 4-5 years.

Or just buy the cars aimed at non-enthusiasts?

Plenty of cars are offered with regular but yet all over, even in reviews from professionals, I see people griping about premium v. regular. Sorry but when a fuel bill is 2500 a year, 2650 gas bill for a luxury brand isn't worth blinking over.

The decision to get or not get a car based on premium v. regular represents such a tiny bump in actual costs that it really is odd to me. This stupid Z4 is over 45k, it's a two seater and obviously aimed at someone who either doesn't have kids or puts little premium on trucking around the little bastages...so is that person going pass on this car over the tiny bump in fuel costs? Flip that, when his brakes need replacing at 25-40k miles, it'll be covered by the "included" maintenance program, so that's a good $500-700 savings. Wait, that covers the gas price bump. So do the oil changes and other service check ups.

Check out the expected maintenance costs on an IS350 C:
$415 $953 $994

The BMW - $0.

Honestly, I think the Lexus takes premium too. :)

I see your points, I was just saying that doing more, with less is more impressive. It is easier to program an engine with more power when using premium. I just dont ever see a reason to pay more, no matter how small the amout, when you dont have too. I was raised in a frugal household and I still live that way. I pay cash for my cars but keep them a long time now. When I bought my new Dodge last week I took a pre made check from the bank and said this is what I am going to pay (I was clued in from my buddy that works at the dealership) and they said "no way we cant do that" so I tore up the check and walked out. The next day I got a call saying if I came back with another check, it was a deal. There is no glory in paying more than you have too.

It looks like a pretty nice engine by most accounts, but I'll miss the NA inline 6, as I'm sure this engine will eventually replace that.

BB: I agree 100% about paying cash and saving money, but I agree with BDC on the Premium/Regular issue. I ran the numbers and if my MS3 used regular I'd save around $13/month. There are a lot better ways to save 42 cents per day.

I agree RB, my point is that it shows a bit more effort and forethought to do it the way American and Asian car companies do. Many that really like European cars often talk about "engineering prowess" as a reason they like their car, and that is fine, but there are fine engineers all over the world. The Germans by no means corner that market anymore.

Premium is the best deal it's ever been, percentage wise. Yet, with prices high in the absolute sense, every penny feels like a dollar, which is obviously purely psychological. I've heard that it may be possible to get the same mileage in my CTS-V if I run it on 87. I might try it as an experiment, though it'll probably be down a few ponies. But until now, I have been using exclusively premium.

I don't care how many balance shafts or other NVH reducing items they throw on this thing, nothing will match the smoothness and power delivery of BMW's straight six. The automotive trend notwithstanding, 4-cylinder does not equal refinement, luxury or class in my mind.

I have no problem with a 4 cyl in a BMW as long is it's in a light car.

If they use a 4 cyl in a 3500lb car then it's pointless. Make the Z4 weigh 2600 lbs and then there will be a reason for this engine.

Getting back to the engine, I found the cutaway display most interesting. For example:

1. 4 counterweight crank. If you look historically more performance oriented I4 engines, they usually have an 8 counterweight crank. And when I say high performance, that usually means higher revving.

2. Very long rods. Just looking at photos makes it hard to be precise, but this engine looks to have a pretty large rod/stroke ratio - possibly close to 2.0:1. This does several things like reducing cylinder side loading and lengthening dwell at TDC - usually things that are well suited to helping high rpm power. I can only think that maybe BMW is using them here because they reduce friction somewhat and allow a very late injection/ignition event to reduce negative work done before TDC.

3. Skinny rods. OK, not econo car skinny, but not the kind of beefy rods you see on really high output engines, or really high revving ones. This is not to imply weakness, just that they don't appear overbuilt.

4. Itty bitty turbo. No wonder it spools up so quickly and is done so early. It's amazing what turbo companies have done with modern tech. 10-15 years ago a turbo that size would have been hard pressed to hit 200 hp. This one will make 240 hp and probably have 20-30% overhead if you want to turn up the boost and push the limits of the center section.

All told, this is definitely an engine with a lot of focus on fuel economy. I'm sure given BMW's history, and their results on the current Mini 1.6 turbo, that it will perform pretty well, but it's too bad that they're being forced in this direction by restrictive regulation rather than a true desire/belief that a turbo 4 is the best thing for their cars.

Hmmm, BMW trying to play catch up, and they never even caught up, with GM on a similar engine. That's right, 2.0L 4-cylinder, direct injected, turbocharged, with VVT DOHC. GM had this engine back in 2007 with the engine in the Solstice GXP and Sky Redline. But with 260hp, instead of 240hp BMW came up with. Exact same torque. I thought BMW was supposed to be engineering masters of the universe? What happened here? They got beat by the OLD GM even.

That was one of the points I was making....this engine seems to be no great feat of engineering. Competitive but not class leading.

I'll wait to see how it actually performs; BMW is notorious for underrating the horsepower of their engines.

"But with 260hp, instead of 240hp BMW came up with. Exact same torque."

You didn't mention the Ecotec's torque peak is at 2000 RPM versus the BMW's 1250. Nor did you mention the RPM range the engine maintains that level of torque. BMW has for decades sacrificed high peak ratings in favor of broad and flat curves for both horsepower and torque. It doesn't look as impressive on paper to spec-racer, but on the dyno and on the road it actually matters. It has given BMW a reputation of under-rating their engines.

One other point; Munich didn't build the N20 to compete in the hot-hatch market. Rather, it is designed to replace a 3.0 liter I6 by providing the same power combined with better fuel economy and lower emissions.

@church123: I also thought it was interesting that the cylinders are tilted so as to make a lower profile engine. Reminds me of the old Dodge slant 6! I also saw the log manifold for the direct injectors, but couldn't identify individual injector electronic controls, so is it all 4 injectors squirting at once with a common mechanical pump to generate the high pressures? Or are those electronics next to the injector metal tubes both injector controls as well as individual spark coils?

I love these closeups and cutaways for new engines! And I'm glad to see BMW getting solid power and huge torque from a 2.0L four, which has to be a lot lighter than the 6 cylinder. Maybe they can put this engine into a next gen Z4 that is much lighter and improve the driving dynamics. Think Honda S2000 weight with substantially more low end torque! Cool!

Great article! I'm going to the BMW site to see if I can uncover more engineering details!

Any guesses on the first HPFP failure for this car? In all seriousness, I really hope BMW has worked out the kinks in their petrol HPFP's as once all their powerplants go boosted I suspect none of their cars will be able to score a 'red' on Consumer reports reliability ratings. (all the N54 TT powered cars all have a poor ratings and rightly so) It's also funny that all these people are going gaga for the death of the NA powerplant in the pursuit for 'fuel economy' Just like everything else in life, you either pay for it up front or later. Whoever decides to keep these cars long-term is going to foot repair bills that will easily dwarf all the fuel economy 'savings' over the much more reliable NA motors.

"I also thought it was interesting that the cylinders are tilted so as to make a lower profile engine."

All of BMW's inline engines(with the exception of the M88/1 used in the E26 M1) have utilized a slanted configuration- going back to the 1499 cc M10 used in the Neue Klasse sedans of the early sixties.

http://www.bmw-02-club.de/technik/tmot_16.jpg

The GS is a great bike, but I'm leaning toward a Tiger 800 XC