BMW M42
Encyclopedia
The BMW
M42 is a DOHC 16-valve I4
piston engine first built for the E30
318is and 318i 1991 year model. The engine block is based on the BMW M40
, used on the 318i, but had distinctive features such as double overhead cams driven by a timing chain, hydraulic valve lifters, and an increased 10:1 compression ratio. The USA version of the 1991 318i only came with the M42 engine.
Profile gaskets on M42s are known to fail prematurely.
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, a two stage intake manifold 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 Bosch
M1.7 fuel injection
.
The M42 is a popular engine swap for 2002s and E21s
. It is a relatively inexpensive swap which gives more usable power than the M10s
, utilizing a more modern cylinder head and EFI
, also distributor-less ignition and later knock sensors.
Applications:
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:
In the last evolution step the engine puts out an amazing 158 hp/L. Compared to a modern racing engine it was a big achievement.
BMW
Bayerische Motoren Werke AG is a German automobile, motorcycle and engine manufacturing company founded in 1916. It also owns and produces the Mini marque, and is the parent company of Rolls-Royce Motor Cars. BMW produces motorcycles under BMW Motorrad and Husqvarna brands...
M42 is a DOHC 16-valve I4
Straight-4
The inline-four engine or straight-four engine is an internal combustion engine with all four cylinders mounted in a straight line, or plane along the crankcase. The single bank of cylinders may be oriented in either a vertical or an inclined plane with all the pistons driving a common crankshaft....
piston engine first built for the E30
BMW E30
The BMW E30 was a compact executive car produced by BMW. It was replaced by the BMW E36 in 1990. BMW continued to produce the cabriolet E30 well into 1993. The Touring remained in production until 1994 when the E36 touring replaced it...
318is and 318i 1991 year model. The engine block is based on the BMW M40
BMW M40
The BMW M40 is an I4 piston engine. Engine displacement ranges from 1600 cc to 1800 cc.-M40B16:The M40B16 is a 1.6 L version of the M40 producing 102 hp of mechanical power and lbf of torque using Bosch M1.3 fuel injection...
, used on the 318i, but had distinctive features such as double overhead cams driven by a timing chain, hydraulic valve lifters, and an increased 10:1 compression ratio. The USA version of the 1991 318i only came with the M42 engine.
Profile gaskets on M42s are known to fail prematurely.
| Engine | Displacement | Power | Torque | Redline | Year |
|---|---|---|---|---|---|
| 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 |
M42B18
Displacement for the M42B18 was 1.8 L (1796 cc); cylinder bore was 84 mm; and stroke was 81 mm. E30BMW E30
The BMW E30 was a compact executive car produced by BMW. It was replaced by the BMW E36 in 1990. BMW continued to produce the cabriolet E30 well into 1993. The Touring remained in production until 1994 when the E36 touring replaced it...
318iS, 318i (in the U.S.; European versions of the 318i were fitted with the M40 engine
BMW M40
The BMW M40 is an I4 piston engine. Engine displacement ranges from 1600 cc to 1800 cc.-M40B16:The M40B16 is a 1.6 L version of the M40 producing 102 hp of mechanical power and lbf of torque using Bosch M1.3 fuel injection...
), and early E36
BMW E36
The BMW E36 is the third generation of the 3 Series compact executive cars produced by BMW. It was introduced in late 1990 for Europe and in late 1991 for US and Canada. It was the successor to the E30 3 Series and was eventually replaced by the E90 3 Series in 2005, though E36 coupes were still...
318iS/318ti (prior to 1992) models were fitted with versions producing 100 kW (134 hp) and 172 N·m (127 ft·lbf). Later, a two stage intake manifold helped to achieve 103 kW (138 hp) and 175 N·m (129 ft·lbf), coping with the increased weight of the E36
BMW E36
The BMW E36 is the third generation of the 3 Series compact executive cars produced by BMW. It was introduced in late 1990 for Europe and in late 1991 for US and Canada. It was the successor to the E30 3 Series and was eventually replaced by the E90 3 Series in 2005, though E36 coupes were still...
models. The engine uses Bosch
Robert Bosch GmbH
Robert Bosch GmbH is a multinational engineering and electronics company headquartered in Gerlingen, near Stuttgart, Germany. It is the world's largest supplier of automotive components...
M1.7 fuel injection
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
.
The M42 is a popular engine swap for 2002s and E21s
BMW E21
BMW E21 is the body designation for the first BMW 3 Series compact executive car, produced by the German automaker BMW from 1975 to 1983. This series was the immediate successor to the BMW 2002 and was superseded by the BMW E30 platform....
. It is a relatively inexpensive swap which gives more usable power than the M10s
BMW M10
The BMW M10/M12 was a straight-4 piston engine produced from 1961 to 1987. Displacement ranged from 1499 cc to 1990 cc.The engine was designed by noted engineer and race driver Baron Alex von Falkenhausen. He was asked to design a small-displacement engine, but felt that this would be...
, utilizing a more modern cylinder head and EFI
Fuel injection
Fuel injection is a system for admitting fuel into an internal combustion engine. It has become the primary fuel delivery system used in automotive petrol engines, having almost completely replaced carburetors in the late 1980s....
, also distributor-less ignition and later knock sensors.
Applications:
- 1989–1991 E30BMW E30The BMW E30 was a compact executive car produced by BMW. It was replaced by the BMW E36 in 1990. BMW continued to produce the cabriolet E30 well into 1993. The Touring remained in production until 1994 when the E36 touring replaced it...
318iS/U.S. model 318i - 1992–1996 E36BMW E36The BMW E36 is the third generation of the 3 Series compact executive cars produced by BMW. It was introduced in late 1990 for Europe and in late 1991 for US and Canada. It was the successor to the E30 3 Series and was eventually replaced by the E90 3 Series in 2005, though E36 coupes were still...
318i/318iS/318ti - 1993–1995 E36BMW E36The BMW E36 is the third generation of the 3 Series compact executive cars produced by BMW. It was introduced in late 1990 for Europe and in late 1991 for US and Canada. It was the successor to the E30 3 Series and was eventually replaced by the E90 3 Series in 2005, though E36 coupes were still...
318i — (Produced in South Africa for South African market only.)
S42B20
Airbox
Motorcyclists and car enthusiasts use the term airbox for what might more properly be described as an air intake chamber. Older engines drew air directly from the surroundings into each individual carburetor...
were entirely made of carbon fiber. Lubrication was provided by a dry sump
Dry sump
A dry sump is a lubricating motor oil management method for four-stroke and large two-stroke piston internal combustion engines that uses external pumps and a secondary external reservoir for oil, as compared to a conventional wet sump system....
system. Compression ratio
Compression ratio
The 'compression ratio' of an internal-combustion engine or external combustion engine is a value that represents the ratio of the volume of its combustion chamber from its largest capacity to its smallest capacity...
was increased and a lightweight head was installed.
Horsepower evolution steps of the S42 Engine:
| Year | 1995 | 1996 | 1997 |
|---|---|---|---|
| 300 hp | 308 hp | 315 hp |
In the last evolution step the engine puts out an amazing 158 hp/L. Compared to a modern racing engine it was a big achievement.