BMW N54B25 engine

The BMW M54 is an atmospheric inline 6 cylinder gasoline engine that was produced from 2000 to 2006.It was released in the E53 X5 and is the replacement for the M52 .

There was another version of the car, the BMW S54, which is the equivalent of the high performance engine that was used in the E46 M3, in the Z3 M coupe/roadster and the E85 Z4 M.

In 2002 and 2003, the M54 topped the top 10 best engines according to domestic and foreign magazines. Production of the N54 was gradually reduced after the introduction of the N52 in 2004

This is another 2.5-liter engine in the N52 series, which also includes the N52B30 inline-6 cylinder engine. It was introduced in 2005 as an alternative to the then popular M54B25 engine. Apart from the previous M-series version, in which each new engine reflected the evolution of the previous one, the new engine proved to be a completely new product.
The N52 engine is based on a revolutionary aluminum-magnesium cylinder block that is lighter than the previous version. It also features new lightweight connecting rods, pistons and a modified crankshaft.

Compared to the latest versions of its M52 predecessor (with the name M52TU), the M54 has a non-return fuel system, fully electronic throttle (no mechanical redundancy), electronically controlled thermostat, Siemens MS 43 for engine management, revised intake manifold, and in the North American version, the engines no longer use an iron block. Performance increased from 2.8 liters to 3.0 liters (2979 cc), due to an increase in cylinder stroke to 89.6 mm (3.53 in).

N54B25 engine specifications

Advantages

Just like the M52TU, the M54 uses an aluminum block and aluminum cylinder head with cast iron cylinder liners. The red mark remains at 6500 rpm. Variable camshaft timing is installed on both camshafts (called “dual VANOS” by BMW) and utilizes an intake manifold called “DISA” by BMW.

There was no “Technical Upgrade” (TU) version of the M54 produced, so engine specifications remained unchanged throughout the 7-year production run.
A new, improved Double-VANOS cylinder head was added to the power unit. A similar one was installed in the N52B25. At the same time, a new Valvetronic system was added to regulate intake valve levels. This allowed for more power as well as lower fuel consumption. A variable length DISA intake manifold is used on the intake. At the same time, the injectors are mounted in the cylinder head.

Later a more productive modification was developed – S54

This powertrain was touted as a high-performance equivalent to the M54, but it is actually more of an evolution of the BMW S50 and is partially similar in technical basis and overall layout to the M54.  Speaking of the S50, the engine block is made of cast iron (as opposed to the aluminum engine block used by the M54). The red line is at – 8000 rpm.

The improved version has a larger cylinder bore, up to 87 mm (3.43 inches), which immediately led to a new powertrain displacement. It reached the mark – 3,246 cc.

Revised variable valve arrangement camshafts (called “VANOS” by BMW) are now also used on the exhaust camshaft.

• Compression ratio increased from 11.3: 1 to 11.5: 1
• Engine control unit – Siemens MSS 54
• Electronic throttle control
• Cleaning the oil pump (to avoid oil starvation when cornering)

There is no direct successor to the S54, as the next generation M3 is powered by BMW’s S65 V8 engine.

The previous engine control unit was replaced by a Siemens MSV70.  This engine was used in BMW models with 23i and 25i indexes.  An alternative to the N52B25 engine was introduced after 2 years of production. It was later replaced by the N53B25 engine as well as its lighter version N53B30. Nevertheless, the N52 2.5 L was produced almost until recently. Its production was stopped only in 2011 .

Disadvantages

The most common problem in the N52B25 is high engine oil consumption. This is due to the fact that the thin oil rings char rather quickly. At the same time, valve stem seals fail quite often. Such problems can occur even after a mileage of 100,000 kilometers. The only solution to this problem is to replace the damaged components.

The new version of the N52NB25 had no such problems. It was first introduced in 2007 and has major improvements.

1. If you don’t address the oil consumption problem as soon as possible, it can contaminate the catalytic converters. This will result in additional costs to replace them. A catback can be a good alternative to a catalytic converter.
2. Constant noise. This problem can occur mainly with engines that were manufactured before 2009. However, it does not have any negative effects on the engine or ride.
3. Rough idle. This problem is mostly related to the Valvetronic, Vanos valves or the flow meter. You should look at all these components.
4. At the same time, overheating is another common problem with this engine. You should always check the cooling system and clean the radiator regularly. At the same time, the N52 engine has a not very reliable electric water pump. It requires replacement every 80,000-100,000 kilometers of mileage.
5. High oil and fuel requirements should also be added.

Chip tuning

This engine is a pretty poor choice when it comes to tuning and upgrading. That’s why the best option is to buy a more powerful BMW model. If you still want to experiment with tuning, implementing chip tuning would be a good idea to increase the power level of the N52. You’ll need a K & N exhaust system and air filter, as well as a tuned ECU to add at least 20 hp to your engine.

Owners of 23i models are advised to buy the intake manifold from the N52B25O1 found in 25i models. This will add an additional 15-20 horsepower. If you feel that you need something more over the aforementioned mods, get ready to spend some money and buy an N52B25 supercharger. The supercharger kit will allow the engine to run up to 300hp with stock internals. However, it will be cheaper to buy a BMW 35i equipped with N54 / N55.

This engine is installed on the following models:

BMW 5-Series (E61)