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Dec 8, 2022
Nowadays, there aren’t many things that increase popularity more than a good controversy. A popular American hip-hop musician repenting and becoming an outspoken believer. A pair of world-famous actors settling their marital affairs in court. Or the reveal of the newest pre-production BMW M2 with its… ugh… “unconventionally designed” grille and rear bumper.
No wonder stuff like that is popular, even in the automotive world. People love discussing polarizing subjects, that’s just the way we are. The BMW N20, which is the main protagonist of this article, conforms to this very description. Valued by some for how advanced it is, disliked by others for its timing chain issues, it’s really quite controversial.
Join us and read on to learn more about this particular engine design, its history, as well as all the problems that troubled it since its release. Oh, and we’ll also tell you what can be done with this unit in terms of performance… stay tuned!
Produced from 2011, the BMW N20 is a turbo inline-four gasoline engine that came in two sizes. The smaller one, called the N20B16, has a displacement of 1.6 L, while the larger variant is labeled as the N20B20 and displaces 2.0 L. Both of them share the same technologies and design characteristics, such as:
Interestingly, the N20s have an electric water pump, instead of a more traditional mechanical one – a technology that is rarely used in newer cars. The main benefits of this solution are no parasitic energy losses and a greater control over how much coolant gets provided to the engine. The margin of error is smaller, allowing for precise dosing and monitoring of anti-freeze. But what does it mean exactly?
In short, the mechanical pumps are usually belt driven, which means they “steal” some of the power produced by the engine to get the anti-freeze flowing. Just like a parasite. When it comes to the more precise cooling liquid dosage, traditional pumps will always work at a speed that is proportional to the speed of the crankshaft. Which means that they will sometimes provide too much coolant when it’s not needed, wasting energy.
All this aside, the electric water pumps do add a bit more complexity to an engine. And that could lead to more potential problems or much more expensive repairs.
It’s also worth noting that the BMW N20 was created as a replacement for a bigger N53 engine – the last naturally aspirated straight-six produced by the Bavarians. Because of that succession, the N20 also represents BMW’s entry into the engine downsizing era.
But how does all of that affect the performance of this engine?
In total, five different versions of the BMW N20 were produced over the years. All of them with varying power outputs – one for the smaller N20B16 and the rest for the larger N20B20. What’s interesting is that despite the differences in displacement and specifications, all N20 versions redline at exactly 7,000 RPM. Quite high for a turbo gasoline engine.
So, what are the power figures of the N20s?
|Engine||Power||Torque||Years of production|
|N20B16||168 HP||250 Nm (184 lb/ft)||2013–present|
|N20B20||154 HP||240 Nm (177 lb/ft)||2013–2017|
|181 HP||270 Nm (199 lb/ft)||2011–2017|
|215 HP||310 Nm (229 lb/ft)||2012–2017|
|241 HP||350 Nm (258 lb/ft)||2011–2017|
As you can see, the N20 didn’t come in a lot of flavors. One of the flavors it did come in, however, was quite impressive – 241 HP out of a 2.0 L engine is a respective number even today. Nevertheless, it still powered a fair share of cars…
Smaller displacement N20 saw only limited use in a couple of markets. From 2013 to 2016 it was installed in the BMW 520i of the F10 generation sold in Turkey. Later on, Turkish, Tunisian, Vietnamese, and Greek BMW dealerships started offering the 520i (G30) and 320i (G20) models powered by this motor.
The larger N20s, on the other hand, were much more popular and found their way under the hoods of many bimmers across the globe.
|Model||Years of production|
|Z4 sDrive18i / 20i / 28i (E89)||2011–2016|
|X1 xDrive / sDrive20i / 28i (E84)||2011–2015|
|X3 xDrive20i / 28i (F25)||2011–2017|
|X3 sDrive18i (F25)||2013–2017|
|X4 xDrive28i (F26)||2014–2017|
|X5 xDrive40e (F15)||2016–2018|
|220i / 228i (F22)||2014–2016|
|320i / 328i (F30)||2011–2016|
|320i / 328i GT (F34)||2013–2016|
|420i / 428i (F32)||2014–2016|
|520i / 520Li / 525Li / 528i (F10)||2011–2016|
From the Z4, through X1, up to the 5 series… The 2.0 L N20 was offered in a wide range of BMWs, excluding only the most sophisticated vehicles of the manufacturer’s lineup.
However, not all of the cars listed above came equipped with the regular N20B20. If you are from the United States, chances are that your BMW is equipped with a modified version of this engine: the N26. What sets the two apart?
Long story short, the N26 is the N20 that has been slightly altered to comply with the American Super Ultra Low Emissions Vehicle classification. Usually abbreviated to SULEV, it’s the standard given to vehicles that are 90% cleaner than the average gasoline-powered car of the given year.
But just how similar are these engines? Well, they share around 95% of their components. The only elements that have been changed are the ones that directly affect the emissions. This means revisions in the following departments:
Luckily for the BMW drivers from the US, the changes described above don’t affect the performance of the cars. When driving, both designs behave exactly the same. The N26B20 came in only one variant, producing identical figures as the most powerful version of the N20: 241 HP, 350 Nm (258 lb/ft) of torque, and a redline of 7,000 RPM. It powered three BMW models:
Before we dive deeper into the issues of the N20 and talk about its reliability, let’s take a closer look at what came after. It’s actually very interesting to see how BMW improved their design in a way that wasn’t a revolution, but rather an evolution…
Regardless of the problems encountered by the users, the BMW N20 was, in general, a very well-designed engine. After all, it was hailed one of the Wards Top 10 Engines in the 2012. Its troubles were mostly limited to the materials used to manufacture certain elements; but more on that in a bit. And so many design characteristics of that motor got carried over to its successor, the BMW B48 engine.
Just like the N20, the newer powerhouse also uses Valvetronic, Double VANOS, and direct gasoline injection. They both have turbochargers of the same twin-scroll type as well as a compression ratio that is relatively high for a turbo engine (10.3:1 for the N20 and 11.0:1 for the B48). Oh, and they both rev up to 7,000 RPM.
When coming up with a replacement for the N20, Bavarians set out to focus on improving the reliability of their design.
Although the N20s weren’t really known for weak internals, BMW introduced upgrades even in this aspect. Because of that, B48 now relies on forged parts, instead of cast ones. The engine block design is also different for the two – in the B48 they went for a slightly heavier, but vastly more durable closed-deck kind that can tolerate higher boost pressures.
Now we know what BMW has changed over the years of their engine development. But what was there to change in the first place, when it comes to the N20?
As we’ve already mentioned, the BMW N20 is overall a great engine from the design standpoint. However, it fell short in two departments: intake temperature and material composition.
The air temperature that is sucked in by the N20 is relatively high when compared to other turbocharged engines, which makes it a bit challenging to tune this unit. Luckily, it’s not impossible to reliably improve its power output or behavior and we’ve found just a way to do it. Keep on reading to learn more about perfecting the BMW N20 performance!
And the materials? Well, to be more exact, the plastic guides of the timing chain were poorly made, which could potentially lead to a costly failure – but let’s start at the beginning.
A few years after the introduction of the BMW N20 engine it was discovered that the material composition of the timing chain guides in thousands of early production units could be defective. This causes them to lose flexibility over time, leading to a much faster deterioration, and finally breaking down of the guides.
When the guides break, it’s only a matter of time before the engine gets toasted. And we are not even being overly dramatic: without the guide, the timing chain becomes loose. A loose chain, in turn, skips time, changing the piston-to-valve synchronization and making those parts touch each other. No, they aren’t meant to do that!
But why exactly is the engine timing so crucial? To answer this question, it’s important to know how modern four-stroke engines work. In short, a stroke is what the full travel of each piston is called. The four strokes are:
In case of the direct injection engines, the fuel gets sprayed into the cylinder at the end of the compression stroke. This happens right before ignition, instead of gasoline being mixed with the air right away.
To control when the appropriate valves should open, when to inject fuel or when the spark plugs should ignite, all of the components need to be synchronized. Or timed, if you’d prefer a more technical terminology. That’s where you need some sort of a timing system. One of the most popular options is the timing chain, which is also what’s present on the BMW N20 engine.
The way it works, the BMW N20 timing chain transfers rotation from the crankshaft to both camshafts through toothed gears that it’s wrapped over. Two rotations of the crankshaft are required for a complete four-stroke cycle and the camshafts have to be driven at half the speed of the crankshaft – this is done by using smaller gears on the cams.
Knowing why the engine timing is so essential, you probably get the idea why the defects of the BMW N20 timing chain guides were such a critical flaw. BMW discovered this problem and at the beginning of 2015 redesigned the faulty component.
Additionally, after a BMW N20 timing chain lawsuit in 2017, they have also extended the warranty for the potentially affected models powered by both N20 and N26 engines. Note that the extension only covers the timing chain and oil pump assemblies, not the entire cars. Despite the BMW N20 timing chain warranty extension, a full-fledged timing chain recall didn’t happen.
Which means that when buying a used bimmer, you might come across one that still has the problematic components installed.
Being one of the most vital parts of an engine, timing belts or chains are pretty difficult maintenance-wise.
Because they are hidden, it’s not easy to access all of the pulleys and tensioners making up the system, and properly putting them back together requires the precision of a watchmaker. In addition, the chains need oil for lubrication, so the cover of the entire assembly has to be sealed correctly, to prevent any leaks. All of that amounts to the BMW N20 timing chain replacement cost that could be pretty high.
After the lawsuit we’ve mentioned earlier, the warranty of the affected models has been extended by 7 years or 70,000 miles. So for the cars that haven’t yet reached the specified mileage, the warranty should still be available up to 2024.
Aren’t certain if your bimmer has already had its timing chain issue resolved? If it was produced prior to March 2015 and if it has the N20 or N26 engine, you should visit your car mechanic to verify the timing system condition.
However, there is some good news – the BMW N20 reliability. Apart from this one timing chain fluke, which has been remedied in models produced after the 2015 redesign, the N20s are quite reliable. There are countless vehicles powered by this unit out on the roads, making hundreds of thousands of kilometers (or miles).
But is the N20 durable enough to reliably handle a performance modification?
The simple answer is “yes.” Now, before you get confused, hear us out. When carried out carefully, engine tuning results in not only brutal power increase, which is the domain of piggyback tunes – we’ve talked about their pros and cons in one of our previous posts.
Generally speaking, box tuning (as piggybacks are sometimes called) is not a performance improvement method we recommend. Especially in the case of the N20, which requires special care, due to high intake temperatures we’ve mentioned earlier. To reliably tune this powerhouse without increasing its operating temperature, very precise parameter changes are needed. The lack of customization and the fact that piggybacks tend to make the car run hotter disqualifies them from the BMW N20 engine tuning.
Surprised that there is more to be gained through engine tuning with this unit? If you decide that you need to squeeze something extra out of your car with this method, you can expect changes in three areas:
Thanks to all of the above changes, you’ll be able to fully enjoy your car for a much longer time and with a much lower fuel consumption.
Going for the best results with engine tuning, you will want to choose our Perfected Performance service – we’ll take care of the complex stuff, you’ll just have to connect your car and your laptop with the ENET cable. Check out the full BMW N20 engine tuning guide here!
…which could be the title of a movie about the BMW N20 engine. If they were to make one, of course. But, as opposed to the world of pop culture, the automotive industry isn’t very forgiving to controversies. Many otherwise great designs have been abandoned due to the poor reception or some initial flaws that troubled them.
That being said, the N20 engine didn’t really share their fate – because of its durability in aspects other than the timing chain guide as well as the service action by the BMW, it managed to save some of its reputation.
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