BMW M73B54 engine

Production of the 12-cylinder power unit started in 1993. During the entire assembly period, 26,435 M73B54 engines were created. The 5.4-liter gasoline motor is equipped on the BMW 7 and 8 series, bodies E38 and E31, respectively. The M73B54 engine is capable of gaining up to 326 horsepower. The structure of the installation is largely similar to the previous version of the M70.

The construction of the M73B54 has been lightened due to the aluminum included in the cylinder block. The cylinder head also consists of aluminum alloy. The design of the intake manifold and valve covers is made of metal. The engine is V-shaped, equipped with a water cooling system. The cylinder block has a camber angle of 60 degrees. In the structure of the M73B54 there are 24 valves. The device of timing has not changed, there are two valves per cylinder. The drive of the timing mechanism is a roller single-row chain.

The main distinguishing characteristic of the M73B54 is the presence of a single overhead camshaft with two valves per cylinder. In addition, the unit is equipped with cylinder-by-cylinder regulation of detonation protection. According to the owners’ feedback, the engine became even more warm, which is rather a disadvantage.

Thanks to the introduction of the DME M5/2 electronic engine management system by the manufacturers, the parameters of environmental friendliness, comfort, quality and performance have been improved. A significant increase in power and torque is achieved by increasing the engine displacement to 5.4 liters. In turn, the capacity has been increased by increasing the piston stroke to 79 mm. The cylinder diameter is 79 mm.  Also, among the characteristics of the M73B54 can be noted the presence of an electronic power system with distributed fuel injection. The dry weight of the BMW M73B54 engine is 149 kg.

Gasoline consumption varies from 10.3 to 16.8 liters per 100 km of travel. The engine is susceptible to the quality of fuel, so for proper operation and to avoid malfunctions it is recommended to use premium gasoline with AI-95 or AI-98 markings.

M73B54 engine specifications

Disadvantages

According to reviews of BMW owners with M73B54 engine, the motor is characterized by reliability. Motorists often encounter valve burnouts. The cause of the problem is untimely oil change. In addition, it is important to monitor the oil level, because the consumption can reach 800 g/1000 km, which is quite a high indicator, signaling the presence of malfunctions. Replacement of the intake and exhaust valve seals will help to reduce consumption. The cause of detonation of the motor, as a rule, is the use of poor-quality gasoline with a low octane number. It is also recommended to perform a scheduled oil change every 10,000 km.

If the driver notices air intake through the throttle plate, the gaskets need to be replaced. When the engine reaches 200,000 km, the chain starts to rattle when the engine is revved up. Accordingly, a complete new chain should be installed rather than individual parts.

The BMW M73B54 sometimes exhibits unstable idle speeds. The problem may be due to air infiltration into the intake system. To prevent the M73B54 trojan, the spark plugs should be checked. In general, the engine with proper operation and timely replacement of consumables will be able to serve long enough without major repairs. It is important that all spare parts are available, but sometimes their cost hits the budget hard.

Oil

Every car owner asks the question: “What oil should be poured?”. The fact is that the M73B54 engine is unpretentious to engine oil, so the list of lubricants is quite wide. The only mandatory criterion is the use of synthetic motor oil, because of the high performance of the engine mineral grease is not suitable. As a rule, the optimal options are 5W40, 10W40.

Chip Tuning

Engine M73B54 without installation of additional devices shows decent power characteristics. For this reason, tuning of this power unit is rarely performed. Most often, the control unit is changed to a more advanced one. Cylinder liners boring gives a very small increase in power, so this option is the least effective.

The best result is observed when installing nozzles from the sport version of the BMW. As a rule, they fit together without additional modification.

This engine is installed on the following models:

BMW 7-Series (E38)

BMW 8-Series (E31)