Engine - M42 Description: Overview
90bmw09 GROUP 11 EngineBulletin Number 11 03 90 (2100)
Woodcliff Lake, NJ April 1990 Service Engineering
SUBJECT: 1.8 Liter Four Cylinder Engine (M42)
MODELS: 318i and 318is
BMW has developed a completely new 16 valve, four cylinder engine which is ideally suited for the E30 vehicle. The new M42 engine will be found in two new 3-Series models designated the 318i and 318is.
This engine follows the tradition of other BMW multi-valve engines in that it provides high performance characteristics with excellent routine driveability.
The principle features of the new engine concept are a very flexible power band and excellent torque in relation to the engine displacement of 1.8 liters. Despite the high compression ratio of 10:1 and a power output of 134 bhp, the M42 is a refined, easy-to-drive unit which is especially compatible with everyday use.
Satisfactory acoustic levels are maintained with the use of new technologies and sound insulation techniques.
Low speed vibrations are eliminated with the use of a dual mass flywheel. Refer to TRI # 11 02 81 (2088) for complete dual mass flywheel information.
Optimum thermal efficiency enables the M42 to provide high power output with minimal exhaust emissions and excellent overall economy.
The new M42 engine exhibits the typical neat appearance and pipe and cable layouts which are found on all present day BMW engines. M42 maintenance requirements are reduced and access to existing service points (spark plugs, oil service) has been simplified.
Cylinder head porting and the inlet and exhaust pipes are designed with adequately large cross sections to provide optimum volumetric efficiency.
The precise cross section and length of the intake manifold runners ensure effective cylinder filling.
Combustion chamber type and design with the centrally located spark plug result in much shorter flame paths and a more uniform combustion process.
The heart of the new M42 engine is a new crankcase manufactured of pearlitic gray cast iron.
The new crankcase features siamesed cylinder bores and integral oil spray jets for piston cooling. The engine is installed with a 300 inclination to the right.
The predominant feature of the M42 engine is the chilled cast aluminum cylinder head, which uses the crossflow principle. The intake and exhaust parts are computer designed and are machined with special cutters for optimum gas flow.