BMW N52


The BMW N52 is a naturally aspirated straight-six petrol engine which was produced from 2004-2015. The N52 replaced the BMW M54 and debuted on the E90 3 Series and E63 6 Series.
The N52 was the first water-cooled engine to use magnesium/aluminium composite construction in the engine block. It was also listed as one of Ward's 10 Best Engines in 2006 and 2007.
In European markets, the N52 began to be phased out following the release of the BMW N53 in 2007. However, in markets such as the United States, Canada, Australia and Malaysia, the N53 was deemed unsuitable due to the high levels of sulfur in the fuel. From the year 2011, the N52 began to be replaced by the BMW N20 turbocharged four-cylinder engine until production of the N52 finished in 2015.
Unlike its predecessors, there is no BMW M version of the N52.

Design

Compared with its M54 predecessor, the N52 features Valvetronic, a lighter block due to the use of a magnesium alloy and an electric water pump and a variable output oil pump. The redline was increased from 6,500 rpm to 7,000 rpm.
Like the M54, the N52 uses electronic throttle control and variable valve timing. Higher output versions of the N52 use a three-stage variable length intake manifold.
The N52 engine block is made from a combination of magnesium and aluminium. Magnesium is lighter than aluminium, however it has a greater risk of corrosion from water and may creep under load at high temperatures; this makes traditional magnesium alloys not suited for withstanding the high loads to which an engine block is exposed. Therefore, BMW used a magnesium alloy for the crankcase shell, with an aluminum 'inner block' to overcome the limitations of magnesium alloys. The cylinder liners are made of Alusil and a hollow camshaft is used to reduce weight.
The engine control unit is a Siemens MSV70.

Models

EngineDisplacementPowerTorqueYears
N52B25
at 5,800 rpm
at 3,500-5,000 rpm		2005-2008
N52B25
at 6,400 rpm
at 2,750 rpm		2007-2011
N52B25
at 6,500 rpm
at 2,750-4,250 rpm		2005-2011
N52B30
at 6,100 rpm
at 2,500-4,250 rpm		2006-2010
N52B30
at 6,100 rpm
at 2,500-3,500 rpm		2010-2011
N52B30
at 6,500 rpm
at 2,750 rpm		2007-2013
N52B30
at 6,500 rpm
at 2,750 rpm		2008-2011
N52B30
at 6,600 rpm
at 2,500-4,000 rpm		2010-2011
N52B30
at 6,600 rpm
at 2,600 rpm		2009-2015
N52B30
at 6,600 rpm		 at
2,750-4,250 rpm		2005-2009
N52B30
at 6,650 rpm		 at
2,750 rpm		2006-2010

N52B25

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The models of the N52 have a bore of, a stroke of and a compression ratio of 10.7:1. Variations in power output are often due to different intake manifolds and variations of engine management software.
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The N51 engine is a SULEV version of the N52 that was sold in parts of the United States that had SULEV legislation. Differences to the N52 versions include a variable-length intake manifold with three stages instead of one, and a compression ratio lowered from 10.7:1 to 10.0:1.

Recalls

In 2017, BMW recalled 740,000 six-cylinder models, due to reports of the heater for the crankcase ventilation valve short-circuiting and causing a fire.