From BMW Tech
|Car classification||DOHC Straight-4|
|Internal combustion engine||1.8 L (1796 cc/109 in³)|
The BMW M42 is a DOHC 16-valve Straight-4 Piston engine first built for the E30 318is 1989 year model. The engine block is based on the BMW M40, used on the 318i, but had distinctive features such as Double overhead cam driven by a timing chain, hydraulic valve lifters, and an increased 10:1 compression ratio.
Profile gaskets on M42s built before 1993 are known to fail prematurely.
|M42B18||1.8 L (1796 cc/109 in³)||100 kW (136 PS) @ 6000||172 N·m (127 ft·lbf) @ 4600||6500||1989|
|103 kW (140 PS) @ 6000||175 N·m (129 ft·lbf) @ 4500||6300||1992|
Displacement for the M42B18 was 1.8 L (1796 cc); cylinder bore was 84 mm; and stroke was 81 mm. E30 318iS, 318i (in the U.S.; European versions of the 318i were fitted with the M40 engine), and early E36 318iS/318ti (prior to 1992) models were fitted with versions producing 100 kW (134 hp) and 172 N·m (127 ft·lbf). Later, change in the overhead cam design helped to achieve 103 kW (138 hp) and 175 N·m (129 ft·lbf) coping with the increased weight of the E36 models. The engine uses Robert Bosch GmbH M1.7 Fuel injection.
The M42 is a popular engine swap for 2002s and E21s. It is a relatively inexpensive swap, and produces more usable power than the M10s, while still being lighter, plus utilizing modern Fuel injection and Distributor and a much improved valvetrain.
Further, the long-stroke forged crankshaft from the M47 motor coupled with an overbore of +2 mm will make for a 2.1 L Stroker M42. The 86 mm pistons from a European 3.0 L S50 will produce a high compression, stroker M42 when coupled with the M47 crank. The addition of a MAF conversion from an M50 engine and properly setup cams, valvetrain, and tuning will yield potent output from the "lowly" M42.
- 1989-1991 E30 318iS/U.S. model 318i
- 1992-1996 E36 318i/318iS/318ti
- 1993-1995 E36 318i - (Produced in South Africa for South African market only).
A racing version of the M42 Engine, called the S42 is known. It was used in BMW´s 320 4-door touring car, participating in the German racing series called STW (Super Tourenwagen Cup). It differed by having individual throttle bodies (ITB) for each cylinder and its capacity was enlarged to 1999 cc. It had eight fuel injectors instead of the standard four. Valve cover and Airbox were entirely made of carbon fiber. Lubrication was provided by a Dry sump system. Compression ratio was increased and a lightweight head was installed.
Horsepower evolution steps of the S42 Engine:
|300 hp||308 hp||315 hp|
In the last evolution step the engine puts out an amazing 158hp/ltr. Compared to a modern racing engine it was a big achievement.