The BMW N46 is a naturally aspirated inline-four piston engines which replaced the BMW N42 and was produced from 2004 to 2015.
The N46 serves as the basis for the smaller BMW N45 engine (which does not have Valvetronic).
In 2007, the N46's successor - the BMW N43 - was introduced. However, the direct-injected N43 was not sold in countries with high-sulfur fuel, so the N46 continued to be produced alongside the N43. The N46 continued production until 2015, when the last N46 models were replaced by the BMW N13 turbocharged four-cylinder engine.
Design.
Compared with its N42 predecessor, the N46 features a revised crankshaft, intake manifold and valvetrain. In 2007, the N46 was updated, which was known as the N46N. Changes included the intake manifold, exhaust camshaft and the engine control unit was changed from Bosch Motronic version ME9.2 to version MV17.4.6. The redline is 6,500 rpm.
Versions.
N46B18.
The N46B18 has a displacement and produces and .
Applications:
N46B20U0.
The N46B20U0 produces and .
N46B20U1.
The N46B20U1 produces and .
Applications:
N46B20U2.
The N46B20U2 produces and . It was used instead of the N43 engine in countries with high-sulfur fuel.
Applications:
N46B20A.
The N46B20A produces and .
Applications:
N46B20O1.
The N46B20O1 produces and . On models with secondary air injection, peak torque occurs at 3750 rpm instead of 3600 rpm.
Applications:
N46NB20.
The N46B20 produces and . It was used instead of the N43 engine in countries with high-sulfur fuel.
Applications:
N46B20 engine number key code: 
References.
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