BMW N55 Engine – 3.0L Turbo Inline-6
BMW’s N55 engine is a 3.0L inline-6 turbocharged, direct injection gasoline engine produced from 2009-present. The N55 was a big generational leap for BMW turbocharged engines and it introduced some very important elements to future engine generations.
Unlike the true twin-turbo BMW N54 engine that preceded it, the N55 uses a single twin-power turbocharger, which would become a mainstay in a number of production BMW turbocharged engines like the B48 and B58. Additionally, the BMW N55 was the first turbocharged engine to use both Valvetronic variable valve lift technology and VANOS.
Since the BMW N55’s release in 2009, there have been 5 distinct variants of the engine, each with their own unique changes and attributes. The N55 has been used in a wide variety of BMWs since its release including cars as small as the E8X 1-Series, all the way to some of BMW’s largest vehicles like the F16 X6.
This page is the ultimate resource for everything BMW N55. We provide a general overview and technical information on the engine in addition to problems, performance modifications, FAQs, and various other resources. Whether you own a BMW N55 or are looking to purchase one, we have the most comprehensive N55 information on the internet.
N55 Engine Overview
The BMW N55 is a 3.0L turbocharged inline-6 engine. The N55’s horsepower output ranges from 302-365hp straight from the factory. The N55’s output increased as it continued to evolve and new variants were released. The N55 was initially released in the 2009 BMW 335i and introduced the first N55B30MO variant producing 302 horsepower. Other performance-focused variants of the N55 were released later, including the N55B30O0 and N55B30T0, which introduced strengthening and cooling improvements, allowing for more power production.
Many people consider the BMW N55 to be the company’s first reliable turbocharged engine. With so many problems plaguing the N54 before it, the N55 was a breath of fresh air in terms of reliability. The N55’s three straight Ward’s 10 Best Engines awards should be a testament to both performance and reliability.
While the BMW N55 is still a very capable engine in terms of aftermarket performance, it doesn’t come anywhere close to the modifiability of the N54. A lot of that boils down to the N55’s turbo setup. Regardless, the N55 is still capable of withstanding far more power than its factory rating. To learn more about the BMW N55 engine as a whole, take a look at our Ultimate BMW N55 Engine Guide below.
N55 TwinPower Turbo
The BMW N55 was the first turbocharged BMW engine to utilize a twin-scroll turbocharger. While it might be easy to mistake a twin-scroll turbo for a twin-turbo arrangement, they are actually quite different. With a twin-turbo arrangement, like the one found on the BMW N54, two turbos are mounted next to each other on the engine, each supplying boost to their own bank of three cylinders. With a twin-scroll design, one turbocharger is split into two scrolls with an integrated and specially designed exhaust manifold that properly distributes exhaust pulses from each cylinder to the correct scroll. A twin-scroll design, like the one found on the N55, reduces turbo lag, decreases emissions, and improves overall engine efficiency.
The N55’s twin-scroll turbo plays a big role in the engine’s power delivery characteristics and lack of modifiability compared to older twin-turbo designs. The lack of boost lag is perhaps the most pronounced affect of the twin-scroll design. The lack of boost lag is due to the fact that the twin-scroll turbo was designed to operate at low and high exhaust flow rates, allowing the turbo to spool at low rpms. While the N55’s TwinPower turbo arrangement is better for overall efficiency, it doesn’t allow for the same power potential that was present in the N54.
BMW’s name for the N55’s twin-scroll turbo system is “TwinPower Turbo,” which encompasses more than the turbo itself. This is essentially a marketing term that means the N55 uses:
- Direct injection
- Twin-scroll turbocharging
BMW N55 vs N54 Engine Differences
We have already covered the main difference between the N54 and N55 in terms of their turbo setups, which is one of the biggest distinctions between the two. With that being said, there are some other important distinctions that make the N55 a more reliable engine overall. In many ways, BMW used the N54 as an experiment to figure out if a turbocharged production engine was feasible in future projects. Ultimately, it was a successful experiment, but the N54 had a number of serious issues, including fuel injector failure, high-pressure fuel pump failure, wastegate rattle, and a number of other commonly cited issues. For the most part, BMW fixed most of those issues with the N55.
The addition of Valvetronic variable valve lift was a massive addition to the N5X platform, which has continued to be used continuously on newer BMW turbocharged engines as well. In short, Valvetronic takes the place of a traditional throttle body and instead uses an extra set of rocker arms and an additional eccentric camshaft to vary intake valve lift. The Valvetronic system not only improves fuel efficiency, but also improves power response and delivery at any RPM.
Fuel injector failure was a common problem on the BMW N54 and was extremely expensive and irritating to fix. A lot of the N54’s fuel injector problems surfaced from the fact that BMW chose to use Piezo injectors on the N54, which provide ultimate fuel delivery accuracy but are complicated and prone to failure. As a result, BMW switched back to more traditional solenoid valve injectors for the N55.
BMW N55 EWG vs PWG
Over the course of the BMW N55’s production cycle, BMW changed the turbocharger’s wastegate design from a pneumatic one to an electronic one. Early model N55’s feature the pneumatic wastegate (PWG) design while N55s made after July of 2013 feature an electronic wastegate. While pnuematic wastegate control relies on vacuum lines and a vacuum pump to open and close the wastegates, electronic wastegates operate electronically, not relying on analog equipment.
Along with the addition of the electronic wastegate itself, N55 models fitted with the EWG also received an upgraded turbocharger with a larger turbine wheel and a freer-flowing downpipe. That not only gave the EWG N55 an edge in horsepower, but also made tuning easier and more precise due to the additional wastegate control. EWG and PWG engines make about the same power and torque in the lower-mid RPM range. However, EWG models get a boost on the top-end.
As an additional note, most EWG N55 models received updated internals to reflect their other upgrades. For instance, all 2014+ EWG N55s received forged connecting rods plus main and connecting rod bearings from the BMW S55 engine. The EWG N55 used in the M235 received a forged crank, and the EWG N55 used in the M2 features an S55 oil pump and baffle system, different hypereutectic pistons, a different turbo manifold, and S55 spark plugs.
General BMW N55 Information & Resources
N55 Engine Specs
|Fuel System||Direct Injection|
|Engine Block||Aluminum, open deck|
|Valvetrain||DOHC, Valvetronic, Dual VANOS|
|Bore x Stroke||84 mm × 89.6 mm (3.30 in × 3.50 in)|
|Horsepower||302-445 hp @ 6,000 RPM|
|Torque (lb-ft)||295-502 lb-ft @ 4,000-5,000 RPM|
Over the course of the N55’s build cycle, the engine was released in five factory variants. Outside of the N55 variants produced by BMW themselves, Alpina also released a number of performance variants of the BMW N55 as well. Here is a list of some of the BMW-made BMW N55 variants and the primary differences between them:
The BMW N55B30M0 is by far the most common N55 variant out there. Just look at that list below. The M0 was also the first N55 variant released in the BMW 335i. In its initial form, the N55B30M0 shared even more in common with the N54, including a front timing cover-driven high-pressure fuel pump. The B30M0 received a refresh in 2014 that changed the fuel pump design, added an electronic wastegate, and allowed for a larger turbocharger.
The N55B30O0 came along in 2013 as a performance-focused version of the N55B30M0. Due to the fact that the B30O0 was used in M-performance models, BMW reinforced the N55 a bit more. The N55B30O0 came with a forged steel crankshaft. Combined with a larger intercooler and radiator than the N55M0, the N55B30O0 is ready for additional modifications and tuning.
The N55B30T0 is the top-of-the-line variant of the N55, produced by BMW at least. While the N55B30O0 was built for M-performance models, the N55B30T0 was built primarily for the full-blown M2. As such, the B30T0 is a no-nonsense engine. The B30T0 borrows rods, pistons, spark plugs, and its oil pan from the M-spec S55 engine.
At this point, the BMW N55 has been used in a wide array of BMW vehicles ranging from the compact 1-Series all the way up to the X6. Here are the BMWs that currently utilize the BMW N55 engine:
BMW N55B30M0 (302 Horsepower)
- 2009–2017 F10/F11/F07 535i
- 2010–2013 E90/E91/E92/E93 335i
- 2010–2013 E82/E88 135i
- 2010–2017 F25 X3 xDrive35i
- 2011–2013 E70 X5 xDrive 35i
- 2011–2015 F30/F31 335i
- 2011–2014 E71 X6 xDrive 35i
- 2012–2015 E84 X1 xDrive35i
- 2013–2016 F32/F33/F36 435i
- 2014–2018 F15 X5 xDrive 35i
- 2014–2019 F16 X6 xDrive35i
- 2014–2016 F26 X4 xDrive 35
BMW N55B30 (315 Horsepower)
- 2011–2018 F06/F12/F13 640i
- 2012–2013 E82/E88 135is
- 2012–2015 F20/F21 M135i
- 2012–2015 F01/F02 740i/Li
BMW N55B30O0 (322 Horsepower)
- 2013–2016 F22/F23 M235i
- 2015–2016 F20/F21 M135i LCI
BMW N55B30T0 (355-365 Horsepower)
- 2016–2018 F87 M2
- 2015–2018 F26 X4 M40i
We have compiled some of the most commonly cited BMW N55 engine problems. While the N55 has a pretty decent reputation for reliability, there are still some problem areas with the 3.0L turbocharged inline-6. Due to their many similarities, the N55 shares quite a few common problems with the N54. N55 oil filter housing gasket leaks, valve cover gasket leaks, PCV valve failures, and water pump failures are all common issues with the N55 and are good to know about if you drive an N55-powered BMW.
Take a look at the dropdown menu below to learn more about these problems or check out the more in-depth problem and maintenance guides featured below.
N55 Problems & Maintenance Guides
We have the most comprehensive resources for N55 performance upgrades. This section includes some of the most popular, cost-effective, and value-focused modifications for the BMW N55 engine. While the N55 might not be as modifiable as the N54, there’s truly no limit to what can be done to the 3.0L BMW inline-6. From tuning information to performance parts suggestions, we have you covered as far as BMW N55 modifications are concerned.
Click on each modification to get a brief rundown of the mod, the benefits, and our best product recommendation. Additionally, we have full in-depth guides for each of these modifications that you will find within the sections. Furthermore, a list of general performance and modification-related content can be found below, covering power limits, boost levels, and various other N55-specific topics.
Additional N55 Performance Guides
We have an extensive FAQ article that covers performance upgrades, power levels, general maintenance, problems and reliability, and more for the N55. We’ve included a few performance and reliability-related questions below but recommend reading our full FAQ guide for more extensive questions and details about the N55.
How much power can the N55 handle?
The N55 can handle around 550whp and 550wtq on the stock engine block and internals. The N55 took a small step down in strength compared to the older N54. It’s still a fairly strong motor, but seems a little less tolerant to abuse. The most common places for a BMW N55 engine to fail are its piston rings, connecting rods, and rod bearings. With that being said, the N55’s block is surprisingly tolerant for an open deck design, often said to be able to support between 600-700whp.
How much power and boost can the stock N55 turbo handle?
The factory N55 turbo is capable of making up to roughly 25-26psi. In most cases, the factory N55 turbo is good for low-400 horsepower figures before a turbo upgrade is needed. However, for reliability and longevity reasons, we recommend limiting boost to about 20-21psi. Much over 21psi pushes the turbo well outside its efficiency range for minimal performance gains. Additionally, altitude increases cause the turbo to work harder.
How reliable is the BMW N55?
One of BMW’s main objectives with the N55 was to eliminate or reduce the amount of reliability troubles that plagued the BMW N54 engine that preceded it. In general, they did a good job with that. The N55 is regarded as a reliable engine that holds up well as long as it is properly maintained. With that being said, the N55 does have a number of common problems including oil filter housing gasket leaks, valve cover gasket leaks, PCV valve failure, and water pump failure. With diligent care the block and major engine components should be able to last 200,000 miles – but getting there will likely require a decent bit of maintenance in terms of fuel pumps, gaskets and seals, hoses, and so on.
In-Depth FAQ Guide
8020 Media N55 Videos
Other Helpful N55 Videos
We have dozens of guides on the BMW N55 – check out all of our N55 content below or use the tabs to find our articles on specific modifications, and so on. However, there is also a ton of good content elsewhere around the N55. Check out a few of our favorites here: