BMW N42

The BMW N42 is a DOHC four-cylinder petrol engine which replaced the BMW M43 and was produced from 2001-2004.
The N42 serves as the basis for the smaller N40 engine.
The N42B18 won the 1.4-1.8 L category of the International Engine of the Year awards for 2001.
In 2004, the N42 was replaced by the BMW N46 four-cylinder engine.

Design

Compared with its M43 predecessor, the N42 features a Overhead camshaft#Dual [overhead camshaft|DOHC] valvetrain, VANOS and an aluminium engine block. It was the first BMW engine to have Valvetronic.

N42B18

The N42B18 has a displacement of, uses Bosch Motronic ME9.2 engine management and
Applications:

2001-2004 E46 316i and 316ti

N42B20

The N42B20 has a displacement of, The N42B20 redlines at 6,600 rpm.
The N42B20 replaced older engines like the M43TU and M44B19, and was succeeded by the N46 and N45 series.
Key Technologies:

Double VANOS: Adjusts both intake and exhaust camshaft timing for better torque and efficiency across engine speeds.
Valvetronic: BMW's variable valve lift system, which eliminates the need for a traditional throttle body and improves fuel economy.
DISA Manifold: A variable-length intake system that optimizes airflow for low-end torque and high-end power.
Aluminum Block: Lighter than its cast-iron predecessors, improving weight distribution and fuel economy.

Applications:

2001-2004 E46 318i/318Ci/318ti

N40

The BMW N40 is a DOHC four-cylinder petrol engine which replaced the 1.6 litre versions of the BMW M43. It was produced from 2001-2004 and only sold in several countries, where taxes favoured cars with smaller displacement engines. The N40 was replaced by the BMW N45.

Design

The N40 is based on the BMW N42 engine and uses the same crankcase, pistons and bore size of. The redline is 6,500 rpm.
Unlike the N42, the N40 does not have Valvetronic. The other major difference is a reduction in stroke to, which results in a smaller displacement than the N42.

Versions

Applications:

2001-2005 E46 316i/316ci/316ti