BMW N20 Engine — Reliability, Known Issues, and More – Bimmers.com

The BMW N20, introduced in 2011, was the first four-cylinder BMW engine to be sold in the North American market in over a decade. This turbocharged 2.0L inline-four was considered a replacement to the BMW N52 — a naturally-aspirated, inline-six engine. Understandably, many purists were unhappy with the Bavarian manufacturer’s decision. However, it represented the new direction that the rest of the industry was heading in. There was no longer a place for a naturally-aspirated engine when a turbocharged unit could produce similar output figures while also being more efficient. 

The N20 made its debut in the BMW 528i (F10) and the Z4 sDrive28i (E89) on the U.S. market. Eventually, it powered multiple models in the 1-Series, 3-Series, 5-Series, X3 lineups, and other Z4 variants. If you’re in the market for one of these cars, it’s a good idea to get yourself familiar with the N20. We’ve put together this short guide in an effort to help you with that. Here’s all you need to know about the BMW N20 engine, from the versions available to how much it’ll cost you to own one. 

Photo credit: autowp.ru

Standing On the Shoulders of Giants

While BMW’s core competency is considered the inline-six engine, there’s no denying the significance that the inline-four has had in the company’s past. Straight-four models like the M10-powered New Class and the 2002 Turbo put BMW on the map. The BMW M10 engine spawned an iteration called the M12 that would power a Formula 1 car — one that would win the Driver’s Championship in 1983.

Shortly after, BMW introduced the S14. This iconic engine powered the very first of a line of cars we’ve grown to love — the M3 (E30). 

The N20 came nearly eight decades after BMW had made its first even inline-four, but it represents a pivotal moment in BMW’s history books. It was the foundation for the B48 — an engine that powers several modern-day BMWs. 

Despite the initial prejudice against the N20, everyday buyers and enthusiasts alike soon began to appreciate what it had to offer. The N20 also found itself on Ward’s Top 10 Engines list in 2012.

Technology Behind The N20

The N20 featured a twin-scroll turbocharger, double-VANOS (variable valve timing), Valvetronic (variable valve lift), an electric water pump, and direct injection; this was the tech that was introduced over the previous decade onto inline-four engines like the N40, N42, N46, and N13 — ones that didn’t make their way to the U.S. Consequently, it was pretty reliable by the time it made its way onto the N20. 

The N20 was paired to an 8-speed ZF automatic gearbox or a 6-speed manual, depending on the car it was featured in. Compared to its predecessor, this was also a pretty torque-heavy engine, largely thanks to its undersquare, long-stroke layout. For reference, on the Z4, the N20 produces a whole 60 lb-ft of torque, more than the N52 did! It also comes in earlier in the rev band — nearly 1,500 rpm sooner. 

BMW also worked on tuning the N20 to be more efficient than the N52, claiming that it increased fuel economy by an impressive 20 percent. 

BMW N20 vs N26 

BMW also produced an N26 engine alongside the N20. This was simply a SULEV (Super Ultra-Low Emissions Vehicle) iteration of the engine manufactured for certain states with stricter emission norms. 

The N20 and N26 are essentially the same engines. Changes to the N26 include metal fuel lines, a larger catalytic converter, an additional hydrocarbon filter in the airbox, a redesigned fuel pump, an electronic wastegate, and a fuel tank ventilation system.

Thankfully, BMW tuned the N26 to produce near-identical numbers compared to the N20. The easiest way to see which of these two engines you own is to check the sticker under the hood — it will say ‘ULEV’ for the N20 and ‘SULEV’ if it’s an N26. 

Available Versions 

Internationally, the N20 was available in two main versions — a 1.6L N20B16 and the 2.0L N20B20. However, the former was sold only in select markets like Turkey, Vietnam, and Greece. So, we’re only going to take a look at the 2.0L iteration and its versions that were sold in the U.S. market.

N20B20

The 2.0L N20B20 engine was available in four versions. They were differentiated based on how much power and torque they were tuned to produce, and each powered multiple models in BMW’s portfolio.

Which Cars Is The N20 Used on?

BMW F30 328i
Photo credit: autowp.ru

As we mentioned earlier, this engine was used in multiple models of the 1-Series, 3-Series, 5-Series, X3, and Z4.

154 HP Version

This was the least powerful version of the N20 produced from 2013 to 2017. It featured on the E89 Z4 sDrive18i and the F25 X3 sDrive18i. Peak output figures were rated at 154 hp at 5,000 rpm, and 177 lb-ft of torque delivered between 1,250 and 4,500 rpm.

181 HP Version

Produced from 2011 up until 2017, this version of the engine powered the E84 X1 xDrive/sDrive20i, X3 xDrive20i, F30 320i, 320i GT, 420i (F32), 520i and 520Li (F20), E89 Z4 sDrive20i, and the 220i (F22). 

Peak power and torque figures were 181 hp at 5,000 rpm and 199 lb-ft of torque between 1,250 and 4,500 rpm.

215 HP Version

This engine version only powered the F20 125i and the F10 525Li, producing 215 hp at 5,500 rpm and 229 lb-ft of torque from 1,350 to 4,800 rpm.

241 HP Version

With 241 hp at 5,000 rpm and 258 lb-ft of torque from 1,250 to 4,800 rpm, this was the most powerful iteration of the N20 and the one most commonly available in the U.S. market. It sat at the heart of the Z4 sDrive28i (E89), X1 xDrive/sDrive28i, X3 xDrive28i, 328i (F30), 428i (F32), 528i (F10), 328i GT (F34), 228i (F22), X4 xDrive28i, and the X5 xDrive40e. 

The N20 had a 7,000 rpm redline, but, as you can see, peak output figures were produced much earlier in the rev band — unlike its inline-six predecessor, which liked to be revved out with most of its power and torque coming in later in the rev range. With the N20, many enthusiasts noted a steady decline in performance once you got past the 3,500-5,000 rpm sweet spot. 

Therefore, the best way to enjoy the N20 is to keep yourself from running it to the redline and hold revs under 5,500 rpm.

How Much HP Can An N20 Handle?

The N20 is a great engine even in stock form, but some relatively straightforward updates can bring about a notable increase in performance. Some of the most common mods you can make to your car include an ECU remap (or a piggyback ECU), larger air intakes, and catless downpipes. These are easy, go-to mods as they’re mostly bolt-on parts and require no intensive labor. Some owners also swap the twin-scroll turbocharger on the N20 for a larger, single-scroll unit. 

ECU tunes can quickly bring about an additional 50 hp and 50 lb-ft of torque gain on the most powerful version of the N20. For just a tune, this is a fairly impressive bump in performance. 

With a larger turbocharger, higher boost pressure, and a catless downpipe, the N20 can easily be tuned to produce upwards of 350 hp and 360 lb-ft of torque. Considering this is a well-built engine, it will also support more complex updates, resulting in even higher output figures. 

What Is The Cost of Owning an N20-powered BMW?

Photo credit: autowp.ru

Like with any engine, the running costs of an N20 engine include fluid changes at regular intervals and other wear parts like spark plugs. Yes, there’s the cost of fuel and replacing your tires and brake pads, but we’re going to focus on the engine for now.

Engine Oil

It’s hard to say exactly how often you should change your engine oil. While BMW recommends a 10,000 miles interval on the N20, you may be better off topping it up or changing it earlier depending on how you run your engine. Considering that engine oil is pretty inexpensive, it’s better to be safe than sorry and change it every 7,000-8,000 miles. 

However, if you don’t run your engine too hard, it should be okay, even if you occasionally get past that 10,000-mile mark without an oil change. BMW recommends SAE 0W-40, SAE 0W-30, SAE 5W-40, and SAE 5W-30 viscosity oils. Most N20 engines need about 5 quarts of oil, which should set you back around $30, depending on what brand you choose. 

Engine Coolant

We checked the owner’s manuals of multiple BMWs that feature this engine and we could not find any official information about the engine coolant change interval. That said, coolant does tend to last a long time, and flushing and replacing it is required only every 60,000 miles or so. 

However, if your engine tends to run hot, it might deplete coolant quicker, and you should top it up when needed. Coolant is also relatively inexpensive and will cost you $25-30 for 3.0 liters. 

Spark Plugs and Ignition Coils

Spark plugs and ignition coils are vital in the normal functioning of an engine. If the spark plugs are worn out or degraded, it can result in a loss of power. On the other hand, the ignition coils provide the spark plugs with the necessary charge to ignite the air-fuel mixture in the cylinders. 

On the N20 engine, it’s recommended that the spark plugs be changed every 50,000-60,000 miles. Ignition coils, meanwhile, should be changed every 60,000-75,000 miles. If your engine has been tuned or modded, these parts may wear out quicker and warrant a change earlier on. 

As far as ignition coils go, it’s no secret that modern BMWs aren’t fond of low quality aftermarket coils. Factory coils are known to fail from time to time, which can cause the engine to misfire among other things. The use of quality OEM ignition coils such as Bosch 0221504800 is a known fix to most N20 ignition coil issues. The coils are easy to replace and can be swapped in your driveway.

Is the N20 Engine Reliable?

BMW X3 F25 xDrive20i
Photo credit: autowp.ru

The N20 is a relatively young engine, and there’s been only one significant problem that owners have reported. This was related to the timing chain and even resulted in a class-action lawsuit against the company. Barring this, the N20 suffers from only a couple of other problems, which are seen on some other Bimmer engines. 

Timing Chain Issue

The timing issue was prevalent on thousands of early production N20 engines. These affected engines were manufactured with faulty polymer timing chain guides. An investigation into the matter found that defective polycarbonate compositions were used in making the timing chain guide. As a result, they would break very quickly and cause catastrophic damage to the engine. 

BMW soon rectified the issue by redesigning the component completely. It also offered an extended 7-year/70,000-mile warranty on the timing chain and its parts on the vehicles produced before 2015. If you’re buying a pre-2015 N20-powered engine, this is something you should definitely look into. Has the owner experienced any issues with the timing chain? Have they replaced the part for the redesigned one? Does the warranty still cover it?

If it looks like the cost of replacing it may end up in your hands, you should avoid buying the vehicle. The timing chain can cost a significant amount to replace — even more if it leads to more damage to the engine. 

If you can take the car out on a quick spin, check for a whining noise from the engine. You can also inspect the timing chain itself and look for damage or excess slack, which could indicate an imminent timing chain failure. While these issues are somewhat normal on older timing chains that are nearing the replacement interval, you should take them seriously. 

As we just mentioned, the timing chain problem is more prevalent in pre-2015 cars. Apart from this, here are some of the other issues you should check for on a used N20 car. 

Valve Cover and Valve Cover Gasket

Like with the N52 that it succeeded, the N20 uses a plastic composite valve cover and a rubber valve cover gasket. These components are prone to wear out and eventually harden and crack. This results from the high temperatures they are subject to from proximity to the engine. 

A cracked or broken valve cover or valve cover gasket can result in an oil leak. If this is the case, you should be able to spot leaked oil on the left side of the engine, below the engine cover. Keep an eye out for smoke from the engine bay; this could be a result of oil dripping onto the exhaust or other high-temperature components around the engine. An oil leak means less oil in the engine, resulting in white smoke. 

A minor oil leak won’t result in any significant damage. However, if it’s left unattended, it can result in premature wear of your engine components and parts of the transmission. The good thing is that both these parts are quite affordable and are not very labor-intensive. 

Oil Filter Housing Gasket

A worn-out oil filter housing gasket will result in troubles similar to those brought on by the valve cover and valve cover gasket. The oil filter housing gasket is another rubber component that is prone to wear and tear by the heat from the engine. 

An oil filter housing gasket leak has similar symptoms to a valve cover oil leak. The oil filter housing itself might also crack over time, but this is a much less likely scenario when compared to the gasket. Replacing the gasket is relatively inexpensive, but the housing will set you back a couple of hundred dollars, at least. 

Do You Need BMW N20 Parts? 

Although the BMW N20 is a solid engine, all things considered, it’s not impervious to mechanical issues. When something goes bad on these motors, it’s highly recommended that you use only Genuine or OEM parts to fix whatever went wrong. 

Here at Bimmers.com, we offer one of the largest catalogs of Genuine, OEM, and quality aftermarket parts for BMW. Head over to our store, select your car from the drop-down menu, and you’ll be presented with a list of parts that are a guaranteed fit for your vehicle!