BMW N52 Engine – 2.5/3.0 Inline-6 Engine
The BMW N52 engine is a naturally aspirated straight-6 engine that was produced from 2004-2015. While often overlooked in the argument of the best BMW engines ever made, a strong case can be made for the N52 due to its stellar reliability and versatility. Perhaps due to its underwhelming factory power figures or the fact that the N52 was never placed in any truly special cars, it rarely gets its props.
As the final naturally aspirated straight-six engine that BMW sold in the US before moving to an all-turbo lineup, the N52 represented the last hurrah for an engine formula that BMW is known for. The N52’s smooth and linear power delivery is perfectly representative of exactly how a well-sorted straight-six should behave.
The BMW N52 was available in both 2.5L and 3.0L displacements, with each displacement variant containing subvariants that ranged in power from 174-268 horsepower. 2.5L N52 variants, designated as N52B25, were primarily used in entry-level 23i and some 25i BMW models, while 3.0L N52 variants, designated as N52B30, were used in higher-trim 25i, 28i, and 30i models.
N52 Engine Overview
The BMW N52 is a naturally aspirated inline-six engine that was offered in two displacements, including a 2.5L variant and a 3.0L variant as the N52B25 and N52B30 respectively. Within both the N52B52 and N52B30 variants are further subvariants that were tuned to produce different amounts of power. Within the N52B52 family are 174bhp, 201bhp, and 215bhp sub-variants, while the N52B30 has 215 bhp, 228 bhp, 241 bhp, 255 bhp, 261 bhp, and 268 bhp variants.
The N52 carried on the accomplished reputation of naturally aspirated straight-sixes from winning predecessors, including the BMW M54 which it replaced. BMW made some important changes and revisions to the N52 which modernized their straight-six formula. The N52 was the first water-cooled engine to feature a magnesium/aluminum engine block. The N52 also received some additional modern BMW tech including a new revised version of Valvetronic variable valve lift technology, dual-VANOS variable valve timing, and DISA variable length intake manifolds on high-output variants.
Internals & Major Engine Components
One of the primary aspects of what makes the BMW N52 such a great engine is its strength and lightness. BMW utilized a new and innovative block design for the N52, using a magnesium/aluminum composite material to decrease weight while still retaining strength.
Due to the fact that magnesium has a high probability of corroding over time, it is used for the crankcase shell while an aluminum inner block is used to retain structural rigidity. The N52 also uses Alusil cylinder liners, improving strength further. Overall, the N52’s block can take a healthy amount of abuse with few issues.
It is important to remember that the BMW N52 was built with weight savings at the forefront of its design. As a result, most of the engine’s internals weren’t built with massive power gains in mind.
With that being said, the N52 has shown that it can take double, and almost triple in some instances, the factory horsepower output without issue. Almost all of the N52’s internals are cast with the exception of forged connecting rods. Despite that, the N52 is almost perfectly reliable internally at stock power levels and has plenty of room to grow.
BMW N52 vs N51
The BMW N51 was born out of the need for BMW to create a more efficient engine to meet stricter super ultra-low emissions vehicle emissions regulations in a few states that passed legislation on the subject, the primary of which was California.
The BMW N51 ran concurrently with the BMW N52, and is an almost identical engine despite a few key changes that made it better in terms of emissions regulations. On surface level, both engines are nearly indistinguishable from one another, unless you specifically look for the SULEV emissions label on the N51. The only other way to tell them apart visually is by looking for the Environmental Air Catalyst on the N51’s radiator.
Apart from the subtle visual differences, BMW made some notable mechanical changes to the N51 as well. The two most important changes come in the form of revised cylinder heads and combustion chamber allowing for a lower 10.0:1 compression ratio, and a different, integrated crankcase ventilation system. The N51 also features updated underbody catalysts. Despite the changes made to meet emissions regulations, the N51 is still rated at the same power output as the N52.
BMW N52 vs N52K
In September of 2006, the BMW N52 was modified slightly and given a new engine designation, the N52KP. While the changes were relatively minor, they are still important to note. Most of the changes to the N52 were made as a response to cold weather performance and lifter noise that was concerning to quite a few N52 owners. While BMW attempted to fix the noisy lifter tick noise with the N52K update, it only partially alleviated the issue.
The main updates to the N52KP include a revised crankcase ventilation system integrated into the cylinder head cover, larger 6mm sten diameter exhaust valves carried over from 6/06+ N52s, and a second-generation electric coolant pump. Additionally, small changes were made to the N52K’s camshafts, crankshaft, torsional vibration dampener, and throttle valve. The N52K also received a new DME with the MSV80 designation.
General BMW N52 Information & Resources
N52 Engine Specs
|Displacement||2,497cc (2.5L) – 2,996cc (3.0L)|
|Fuel System||Port Injection|
|Engine Block||Magnesium/Aluminum, Open Deck|
|Valvetrain||DOHC, Valvetronic, Dual VANOS|
|Bore x Stroke||(2.5L) 82mm x 78mm (3.0L) 85mm x 88mm|
|Torque (lb-ft)||170lb-ft – 232 lb-ft|
The BMW N52 was used in a wide array of BMW vehicles ranging from some of BMW’s sportiest models including the Z4, to some of BMW’s family-hauling workhorses like the E70 X5. Here are the BMWs that utilized the BMW N52 engine:
The BMW N52B25 is the 2.5L variant of the N52 engine, which was used in 3-Series, 5-Series, Z4s, and X3s with the 23i designations and some 2.5i designations. As the lowest output variant of the N52, the N52B25 does not receive a DISA variable length intake manifold.
174 Horsepower Variant
- 2006 E90 323i — Canada and Australia
- 2004-2007 E60/E61 523i
- 2006-2008 E85 Z4 2.5i
201 Horsepower Variant
- 2007-2011 E90 323i — Canada and Australia
- 2010-2011 F10 523i
- 2009-2011 E89 Z4 sDrive23i
215 Horsepower Variant
- 2005-2010 E83 X3 2.5si, xDrive25i
- 2005-2010 E60/E61 525i, 525xi — except U.S. and Canada
- 2004-2013 E90/E91/E92/E93 325i, 325xi — except U.S. and Canada
- 2005-2008 E85 Z4 2.5si
The BMW N52B30 is the 3.0L variant of the N52 engine, which was used in a wide number of vehicle applications with 25i, 28i, 30i, and 3.0i designations. The lower tier N52B30 engines are designated as “UL” or “lower output,” and do not receive DISA. However, the more powerful N52B30 variants are designated as N52B30 “OL,” or “high output” engines and receive a three-stage DISA intake manifold.
215 Horsepower Variant
- 2006-2007 E90/E92/E93 325i, 325xi — U.S. and Canada only
- 2006-2007 E60/E61 525i, 525xi — U.S. and Canada only
- 2006-2008 E85 Z4 3.0i — U.S. and Canada only
- 2008-2011 E82/E88 125i
- 2008-2010 E60/E61 528i, 528xi — U.S. and Canada only
- 2009-2010 E84 X1 xDrive25i
228 Horsepower Variant
- 2007-2013 E90/E91/E92/E93 328i, 328xi — U.S. and Canada only
- 2008-2013 E82/E88 128i — U.S. and Canada only
241 Horsepower Variant
- 2010-2011 F10 528i
255 Horsepower Variant
- 2004-2007 E63/E64 630i
- 2005-2007 E90/E92/E93 330i, 330xi
- 2005-2008 E65/E66 730i
- 2005-2009 E60/E61 530i, 530xi
- 2009-2015 F01 730i
- 2008-2011 E89 Z4 sDrive30i
- 2009-2011 E84 X1 xDrive28i
- 2009-2012 E87 130i
- 2010-2011 F25 X3 28i
261 Horsepower Variant
- 2005-2008 E85/E86 Z4 3.0si
- 2006-2009 E87 130i
268 Horsepower Variant
- 2006–2010 E83 X3 3.0si
- 2006-2010 E70 X5 3.0si, xDrive30i
- 2007-2010 E63/E64 630i
- 2007-2013 E90/E92/E93 330i, 330xi
We have compiled some of the most commonly cited BMW N52 engine problems. While the N52 has a very solid reputation for reliability in the BMW community, there are still some problem areas with the 2.5L-3.0L inline-6. N52 lifter tick, valve cover gasket leaks, water pump failures, and oil filter housing gasket leaks are all common issues with the N52 and are good to know about if you drive an N52-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.
N52 Problems & Maintenance Guides
We have the most comprehensive resources for N52 performance upgrades. This section includes some of the most popular, cost-effective, and value-focused modifications for the BMW N52 engine. While the N52 might not be as receptive to modifications as some of the modern turbo engines, there are still plenty of worthwhile engine mods for the naturally aspirated BMW inline-6. From tuning information to performance parts suggestions, we have you covered as far as BMW N52 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 a dedicated BMW N52 Bolt-On Performance Guide if you are looking for more detail on the subjects covered below.
Additional N52 Performance Guides
This engine page covers quite a bit of information about the BMW N52 engine and the various performance upgrades, power levels, general maintenance, problems, and reliability associated with it. If you are looking for a quick answer to a quick question about the BMW N52, take a look at the FAQs listed below.
How much power can the N52 handle?
The N52 is capable of handling upwards of 400whp on the stock block and internals. While there are instances where the N52’s stock internals have supported more than that, reliability has suffered as a result.
Is the BMW N52 the same as the N54?
No, the BMW N52 is not the same engine as the N54. Despite both being a part of the BMW N5X engine series, they are very different engines. The most significant difference between the N52 and N54 is the N54’s use of twin turbochargers while the N52 is naturally aspirated. While the N52 uses a magnesium/aluminum block, the N54 is entirely aluminum. The N54 is also a direct injection engine compared to port injection on the N52. Ultimately, the N52 and N54 share very few components, the main ones being the electric water pump and alternator.
How reliable is the BMW N52?
The BMW N52 is widely considered to be one of the most reliable BMW engines of all time. The N52 has almost no critical common problems, with most of the problems that the N52 does have being typical wear and tear issues that affect a number of other BMW engines. The N52’s most common problems include lifter tick, valve cover leaks, oil filter housing gasket leaks, VANOS solenoid problems, and water pump failure.
8020 Media N52 Videos
Other Helpful N52 Videos
We have a number of guides on specific BMW N52 topics – check out all of our N52 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 N52. Check out a few of our favorites here: