BMW N55B30 engine specifications, problems and reliability

A representative of one of the generations of BMW’s turbocharged inline six-cylinder power units, production of which began in 2009. This engine was intended to replace the somewhat outdated best-selling N54B30, as well as the less popular N62B40.

The engine is based on an aluminum cylinder block with cast iron liners borrowed from the N54. The unit received a lighter weight crankshaft, modernized pistons and connecting rods. The length of the latter is 144.35 mm.

Developers have changed the cylinder-head, improved the system of changing the cam timing, in addition to which they installed the Valvetronic system of the third generation, the function of which is to adjust the valve lift height. The intake units used are 32 mm in diameter, while the exhaust units are 28 mm in diameter. The intake phase is 255 degrees, the exhaust phase is 361 degrees, and the valve lift heights are 9.9 mm and 9.7 mm, respectively. The intake/exhaust systems have been redesigned. Instead of two turbochargers it was decided to use one such device of Twin Scroll type, one of the advantages of which is to provide an even torque band starting from 1200 rpm. The supercharging pressure in the stock version is 0.65 bar. The engine is controlled by Bosch’s MEVD17.2 system.

The motor is intended for installation on BMW cars with 35i and 40i indexes. The S55 unit for the M4 and M5 sports cars was created on the basis of this unit.

N55B30 engine specifications

Power, hp.	300 – 360
Fuel type	Gasoline AI-92 AI-95 AI-98
Volume, cm*3	2979
Maximum torque, Nm (kgm) at rpm.	300 (31) / 5000; 400 (41) / 1200; 400 (41) / 1300; 400 (41) / 5000; 450 (46) / 1300
Fuel consumption, l/100 km	7.9 – 12.1
Engine type	In-line, 4-cylinder
Additional information about the engine	High-precision fuel injection, Valvetronic valve control, Double VANOS timing control
CO2 emission, g/km	163 – 236
Cylinder diameter, mm	84
Number of valves per cylinder	4
Maximum power, hp (kW) at rpm.	300 (221) / 5800; 300 (221) / 6250; 306 (225) / 5800; 306 (225) / 6000; 306 (225) / 6250
Blower	Turbine
Start-stop system	optionally
Compression ratio	10.2
Piston stroke, mm	89.6

Disadvantages

The most obvious negative traits faced by owners of autos with N55 engine are as follows:

Increased oil consumption. Most often, excessive consumption of lubricant is caused by failure of the crankcase gas vent valve.
Ignition misses. This is usually caused by excessive caking of the hydrocompensators. The problem can be avoided by using only high quality oil.
Engine vibration. The culprits of this malfunction are most often worn out injectors, which should be replaced every 80-100 thousand kilometers of mileage.

It is also important to keep an eye on the condition of the fuel pump, which will serve for a long time only when using high-quality fuels and lubricants. In general, this engine model has proved itself mostly on the positive side, as it combines high power, excellent reliability and stability in operation. Also, the manufacturer laid a significant reserve, allowing tuning enthusiasts to refine the installation to their liking.

Modifications

N55B30M0 is the base 306 hp variant with torque at 400 Nm between 1,200 and 5,000 rpm. It is installed on the BMW 35i. It is produced since 2009. N55 – 320-horsepower version with a maximum torque of 450 Nm. It is installed on cars with 35i and 40i index. It is distinguished by a more advanced cooling system and updated firmware for controlling electronics. Produced since 2010.

N55B30O0 is an analog of N55, which has a slightly higher power (326 hp) with the same torque figures. It is oriented on BMW 35i. It is produced since 2011. N55HP – 340-horsepower model with torque of 450 Nm or 500 Nm (in Overboost series). It is installed on 35i model. It is produced since 2011.

The N55B30T0 is a 360 hp motor with an impressive 465 Nm of torque, which is kept between 1,350 and 5,250 rpm. It has been fitted to the BMW 40i since 2015. N55B30O0 – 370 hp unit with a torque figure of 365 Nm (or 500 in the Overboost version). Starting from 2015, this motor is used in the BMW M2.

Chip – Tuning

This power unit, as well as N54, is perfectly suitable for chip tuning. Simple enough manipulations, consisting mainly in the use of downpipes and JB4 Stage 2 firmware, allow you to get from it the output of more than 360 hp. By installing a cold intake, the 380 hp mark can be surpassed without any problems, which will ensure that the quarter mile is completed in about 12 seconds, which is 1.5 seconds faster than the stock time.