BMW N46B20 Engine

  1. Specifications
  2. Overview, problems
  3. Performance tuning

N46B20 Specs

Manufacturer BMW Plant Hams Hall
Also called BMW N46
Production 2004-2012
Cylinder block alloy Aluminum
Configuration Straight-4
Valvetrain DOHC
4 valves per cylinder
Piston stroke, mm (inch) 90 (3.54)
Cylinder bore, mm (inch) 84 (3.3)
Compression ratio 10.5
Displacement 1995 cc (121.7 cu in)
Power output 95 kW (129 HP) at 5,750 rpm
100 kW (136 HP) at 5,750 rpm
105 kW (143 HP) at 6,000 rpm
110 kW (150 HP) at 6,200 rpm
125 kW (170 HP) at 6,400 rpm
Torque output 180 Nm (133 lb·ft) at 3,250 rpm
180 Nm (133 lb·ft) at 3,250 rpm
200 Nm (148 lb·ft) at 3,750 rpm
200 Nm (148 lb·ft) at 3,600 rpm
210 Nm (155 lb·ft) at 4,100 rpm
Redline 6,500 rpm
HP per liter 64.7
Fuel type Gasoline
Fuel system Bosch ME 9.2
Bosch MV17.4.6
Weight, kg (lbs)
Fuel consumption, L/100 km (mpg)

for E90 320i
10.7 (23.5)
5.6 (42.8)

7.4 (32.7)
Turbocharger Naturally aspirated
Oil consumption , L/1000 km
(qt. per miles)
up to 0.7
(1 qt. per 850 miles)
Recommended engine oil 5W-30
Engine oil capacity, L (qt.) 4.25 (4.5)
Oil change interval, km (miles) 7,000-10,000
Normal engine operating temperature, °C (F)
Engine lifespan, km (miles)
-Official information

250+ (155)
Tuning, HP
-Max HP
-No life span loss


The engine is installed in BMW 118i E87
BMW 120i E87
BMW 318i E46
BMW 318i E90
BMW 320i E90
BMW 520i E60
BMW X1 E84
BMW X3 E83
BMW Z4 E85

BMW N46B20 engine reliability, problems and repair

N46 is next generation of 4-cylinder inline engines appeared after N42B20. 2-liter N46B20 version turned out to be the most powerful motor among all N46 engines. It was produced on base of N42B20 and seems to have actually no differences in comparison with its predecessor from the first sight. However there are till some differences between BMW N42 and N46 which include new crankshaft, balance shafts and cylinder head cover. Intake manifold was also renewed and timing chain tensioner was changed. New generators and spark plugs appeared. Valvetronic control block have been additionally integrated into ECU as well as several other slight modifications.
New engine used Bosch ME 9.2 control unit.
In 2007 this engine was modernized. Changed included new intake manifold and exhaust camshaft. Previous engine control system was replaced by Bosch MV17.4.6. Such engines differ with letter N in their name, for example, N46N.
This motor was used in BMW 18i and 20i models.
At the same time N46B20 turned out to be a base for designing N46B18 version.
At the same time it has several related models including N45B20S and N43B20.
This engine was replaced in 2012 by new 4-cylinder turbocharged N13B16.

BMW N46 engine modifications and differences

1. N46B20O0 (2004 – 2007) is base modification of engine with 143 HP at 6,000 rpm and 200 Nm at 3,750 rpm.
2. N46B20U2 (2004 – 2007) is lighter version with another non-DISA intake manifold and another exhaust camshaft. Engine produces 136 HP at 5,750 rpm and 180 Nm at 3,250 rpm.
3. N46B20U1 (2004 – 2007) is equal to N46B20U2 producing 129 HP at 5,750 rpm and 189 Nm at 3,250 rpm.
4. N46B20O1 (2004 – 2007) is another version of engine with 150 HP at 6,200 rpm and 200 Nm at 3,600 rpm.
5. N46B20O1 (2004 – 2007) is equal to abovementioned version with secondary air injection system. It produces 150 HP at 6,200 rpm and 200 Nm at 3,750rpm.
6. N46NB20 (2007 – 2012) is actually the same as 150 HP engine version with new cylinder head cover and exhaust system. At the same time it is equipped by Bosch MV17.4.6 control system producing 170 HP at 6,400 rpm and 210 Nm at 4,100rpm.

BMW N46B20 common problems

1. High oil consumption. Reasons for this problem are the same as in BMW N42 and it is mainly connected with usage of low quality motor oil. Drivers need to use oil that is recommended by BMW brand. Otherwise it can lead to malfunctions in valve stem seals and later pistons rings can also go out of order. Such problem occurs every 30,000 miles (50,000 km) of mileage.
2. Vibration. You can get rid of this problem after you have your Vanos variable valve timing system cleaned.
3. Noise. Reasons are the same as in N42. They are connected with timing chain tensioner or stretching timing chain. It happens after every 60,000 miles (100,000 km) of mileage.
Pay attention that valve cover gasket may leak every 30,000 miles (50,000 km). In this case you need to change it. In some case replacement of vacuum pump may be necessary.
If you want to prevent any kinds of problems and malfunctions you only need to use high quality motor oil which is recommended by BMW specialists. At the same time you need to proceed with regular maintenance and examinations of your N46B20 engine. If you follow these easy tips you are very unlikely to face any problems for a long time.

BMW N46 engine tuning

N46B20 Chiptuning

The easiest way to add some extra HP to your N46B20 is to use aggressive ECU firmware. If you want your upgrade to be as efficient as possible you can also buy cold air intake and cat-back performance exhaust system. It will add extra 10 HP.

N46B20 Supercharger

Apart from firmware supercharger kits are also available on the market. They will let your engine produced 200-230 HP. ARMA is among producers who offer such type of kits. All you need is to purchase supercharger kit and install it on your N46 stock internals. You should note that such modifications are rather expensive. It will cost you almost half price of our BMW auto. This is why it is better to buy BMW M3 E90/E92 or 335i E90/E92.