Engine BMW N45B20S

Engine BMW N45B20S

In 2006, the N45 engine received a new modification – N45B20S with a displacement of 1997 cc. The updated inline 4-cylinder engine differs from its predecessor in terms of power – 126 kW (173 hp). In addition to improving technical characteristics, the main technological improvement of the engine was undoubtedly the use of the innovative Valvetronic system, which significantly increases the efficiency of the entire engine as a whole.


Manufacturer BMW Plant Hams Hall
Also called N45
Production years 2006-2007
Cylinder block alloy aluminum
Fuel system injector
Configuration inline
Number of cylinders 4
Valves per cylinder 4
Piston stroke, mm 88
Cylinder bore, mm 85
Compression ratio 11
Displacement, cc 1997
Power output, hp 177/7000
Torque output, Nm / rpm 210/4250
Fuel type 95
Euro standards Euro 4-5
Weight, kg
Fuel consumption, L/100 km (for 320si E90)
— city
— highway
— combined
Oil consumption, gr/1000 km up to 700
Recommended engine oil 5W-30 / 5W-40
Engine oil capacity, liter 4.5
Oil change interval, km 10000
Normal engine operating temperature, °C
Engine lifespan, km
— official information
— real


Engine BMW N45B20S under the hood

Frequent problems

  1. Knocks inside the motor. The main reason for this, as a rule, is a damaged timing chain tensioner. Moreover, the latter often quickly relax and become unusable after 100 thousand km of run.
  2. Vibrates at idle speed. In this case, the most common cause is the Vanos system. It is cleaned as a repair measure.

Units of the N45 series also have another obvious drawback – the detonation of the fuel mixture. The problem arises from poor quality fuel or oil. The BMW manufacturer strongly discourages the use of any alternative engine oil, since the consequences can be very serious – it may be necessary to carry out major repairs to restore it.

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