BMW N43B20 Engine


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

N43B20 Specs

Manufacturer BMW Plant Hams Hall
Also called BMW N43
Production 2007-2011
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 12
Displacement 1995 cc (121.7 cu in)
Power output 90 kW (122 HP) at 6,000 rpm
105 kW (143 HP) at 6,000 rpm
125 kW (170 HP) at 6,700 rpm
Torque output 185 Nm (136 lb·ft) at 3,000 rpm
190 Nm (140 lb·ft) at 4,250 rpm
210 Nm (155 lb·ft) at 4,250 rpm
Redline 7,300 rpm
HP per liter 61.2
71.7
85.2
Fuel type Gasoline
Fuel system Siemens MSD 81.2
Weight, kg (lbs)
Fuel consumption, L/100 km (mpg)
-City

-Highway
-Combined
for E90 320i
8.3 (28.3)
5.3 (44.4)

6.4 (36.8)
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
5W-40
Engine oil capacity, L (qt.) 4.25 (4.5)
Oil change interval, km (miles) 7,000-10,000
(4,500-6,000)
Normal engine operating temperature, °C (F)
Engine lifespan, km (miles)
-Official information
-Real


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

180+

The engine is installed in BMW 116i E81/E87
BMW 118i E81/E87/E88
BMW 120i E81/E82/E87/E88
BMW 318i E90/E91/E92/E93
BMW 320i E90/E91/E92/E93
BMW 520i E60

BMW N43B20 engine reliability, problems and repair

N43B20 is a new 2-liter version of N42B20 which was produced with several modifications. N43 was equipped with direct injection system. Variable valve lift system Valvetronic was finally removed. New pistons were installed to increase compression ratio up to 12.
Engine had Siemens MSD 81.2. control unit.
It was available in several modifications:
1. N43B20K0 is basic version with 122 HP at 6,000 rpm and 185 Nm at 3,000 rpm. ECU firmware made it possible to decrease the rate of HP. This engine could be found under the bonnet of BMW 16i models.
2. N43B20U0 version produced for BMW 18i models. It produced 143 HP at 6,000 rpm and 190 Nm at 4,250 rpm.
3. N43B20O0 is the most powerful version from this series. It was used in BMW 20i models and produced 170 HP at 6,700 rpm and 210 Nm at 4,250 rpm.
At the same time N43B16 with lower powerful characteristics was produced on base of the engine. N42 – N45B20S and N46B20 4-cylinder successors were constructed along with N43.
In 2011 year of turbocharged BMW engines started. And N43B20 was replaced by N13B16 turbo engines.

BMW N43B20 disadvantages and problems

1. Engine vibration. This problem is one of the most common in N43. You need to change injectors.
2. Misfire and rough idling on N43. The problem is mainly connected with ignition coils. You should check them and replace in case of necessity.
Vacuum pump starts leaking after 40,000-50,000 miles (60,000-80,000 km) of mileage. The only way to solve this problem is to change pump.
Don’t forget to check conditions of your cooling system in order to prevent it from overheating.

N43 is rather demanding when it comes to motor oil and its quality. Operating temperature of the engine is rather high. It means that low quality oil may lead negative consequences for the engine. That is why you need to use motor oil that is recommended by BMW brand.
If you take care of N43B20 engine and proceed with all necessary changed and maintenance, it will serve you for a long time with minimum problems.

BMW N43B20 engine tuning

N43B20 Chip

As well as with previous version of the engine, you will not find any performance parts and details to proceed with N43 upgrade. The only way to increase power in N43 is the same as with N42. You need to buy cold air intake, performance exhaust and complete engine management tuning. It will add extra 10-15 HP. True power fans are not recommended buying N43. You’d better get yourself BMW 335i with N54 or N55.

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