BMW M50B20 engine

The largest German manufacturer BMW AG is famous for its premium class cars. Reliable and durable engines of this brand are characterized by a very wide range and will please any sophisticated owner. Starting from the turbo 3-cylinder B38, 4-cylinder M10-M40 and N20/B48, 6-row M20/M50 and N54/N55 to the first-class V8 M60-N63 and V12 models for the leading series. Powertrains designed for the city and more sporty versions are produced, along with gasoline produced diesel, atmospheric and turbocharged. Everyone can buy a car based on the preferred modification, version and configuration of the motor.  In Russia and the CIS, Bavarian BMW models are also not neglected.

M50B20 engine specifications

Advantages

Under this modification of the engine was developed a new mechanics of the cylinder head, consisting of 24 valves, two camshafts DOHC, intake manifold made of plastic, introduced gas distribution mechanism VANOS, hydrocompensators. The ignition system was technically changed, it became fully electronic, a separate ignition coil was added for each spark plug, the timing drive was replaced by a chain drive with a long service life.

The motor is famous for the fact that, despite the short period of release, it has remained so far popular and on its basis were developed a series of 3-liter engines with an output of 240-250 horsepower, as well as it became the basis for the release of internal combustion engine brand S50 sports car models.

Disadvantages

A list of major difficulties:

1. Floating revolutions, noises in the cylinder head.
   If there are initial signs of insufficient engine traction, it is necessary to inspect the structural units. The source may be the engine decompression mechanism and air suction, ignition coil breakdown. Diagnostics of ignition coils every 100000 km, will prevent the problem of floating revolutions. And in case of damage to the oil rings, they just need to be replaced. Also to eliminate the issue of “floating revs” you need to check the serviceability of the flow meter and Vanos device. The increase in vibration when the unit’s operating temperature sets at idle causes strong jolts and prevents the continuous delivery of fuel. This is due to the individuality of the Vanos mechanism and is considered a factory defect that was eliminated later. The solution may be the purchase of its repair kit.
2. Oil Leakage.
   Timely inspection and replacement of the alternator housing gasket or crankshaft oil seal will prevent such a problem as “engine oil leakage”. If you use analogs of crankshaft oil seals, they should be replaced more often than original consumables.
3. Excessive oil consumption.
   The issue of excessive engine oil consumption is solved by changing oil caps and all components of the oil pipeline every 100000 km, otherwise you may encounter leakage failure of the main oil pipe connections and complete wear of oil caps.
   It is better to immediately put new original oil-resistant rings, as they are of higher quality and will last longer than analogs.
4. Increased fuel consumption.
   Fuel consumption increases due to the collapse of the catalytic converters. Getting the honeycomb of collapsed catalysts into the cylinders will be the consequence of all sorts of scratches. The first signs will be the scuffing of the piston, it begins to curve and hit the top point. With scuffing you can drive of course, but not for a long time, because you will have to buy a new motor, as the price of repair will be high.  Passing maintenance at the dealer, with the extension of the warranty, treatment with composition against wear and scoring NT-10 after timely diagnostics by AGC method will help to avoid it.
5. Air plugs in the cooling mechanism can cause overheating.
   To avoid overheating of the internal combustion engine, it is necessary to prevent the radiator and timely replacement of the fan thermo clutch. Changing the coolant and flushing the mechanism consistently after two years will help to avoid overheating of the engine due to the large number of moving parts of the engine.
6. Trolling is mainly caused by the failure of plugs, injectors and ignition coils and is usually solved by replacing them.

Technical specifications

The M50B20 is an atmospheric gasoline inline 6-cylinder engine with 24 valves, water-cooled and distributed injection of gasoline DME Motronic 3.1 by Bosch, in the intake manifold, DOHC. The intake and exhaust ports of the cylinder head are distributed opposite to each other. The cast iron cylinder block consists of molded cylinders, cooling jacket, crankcase top and 7 crankshaft supports.
The highest output of this 2 liter engine with a volume of 1991 cubic centimeters, counts 150 horsepower / 110 KVT at 6000 rpm. With a torque of 190 Nm and from 4700 rpm, the cylinder cross section is 80 mm and the piston stroke is 66 mm. Piston group under compression ratio is equal to 10.5 and includes 7 pieces of main bearings, there is no supercharger. The combustion chamber has a working volume of 31.6 cubic centimeters with a value of 75 horsepower per 1000 cubic centimeters.

The factory M50B20 TU engine is a gasoline inline 6-cylinder engine with 24 valves, water-cooled and with distributed injection of gasoline MS 40.1 by Siemens in the intake manifold, DOHC. To improve the environmental friendliness of the engine and within the framework of fuel economy, and most importantly to increase acceleration was installed Vanos system. New pistons and connecting rods have been installed, changes have been made in the parameters of valves and crankshaft.
The greatest performance of this 2-liter engine with a volume of 1991 cubic centimeters, has 150 horsepower / 110 KVT at 5900 rpm. With a torque of 190 Nm and from 4200 rpm, the cylinder cross section is 80 mm and the piston stroke is 66 mm. Piston group under compression ratio is equal to 11.6 and includes 7 pieces of main bearings, there is no supercharger. The combustion chamber has a working volume of 31.6 cubic centimeters with a value of 75 horsepower per 1000 cubic centimeters. There is no supercharger. The engine M50B20 TU was mounted on BMW fifth series cars.

Movement of cooling emulsion is made by a water-tight pump driven by the crankshaft and timing belt. To control the temperature of the technical fluid for cooling when the engine is not warmed up, as well as to maintain a comfortable operating temperature, a thermostat is installed in the cooling mechanism. This thermostat of the engine cooling mechanism opens at a temperature of 80-92 degrees and a pressure of 1.5 to 2 bar.

To diagnose the exhaust system, the idle speed of the M50 B20 motors for the step gearbox is 650-700 rpm. To maintain acceptable fuel and air composition and to measure exhaust gas composition, an oxygen sensor with progressive signal change is installed. The ignition module, spark plugs and wires form the microprocessor-based ignition mechanism of the engine, which is not further adjusted or serviced.

Injector engine, with rear-wheel drive and 5-speed manual, are controlled by the electronic system Motronic 3.1 by Bosch /Siemens MS 40.1 Based on lambda probe data, the system calculates the opening time of the injection valves, favorable for fuel and air matching, which is certainly not calculated when regulating manually. In the upper part of the gas distribution system there are two camshafts, just above the cylinder block, which increases the power of the unit, evenly distributes the load, reduces gasoline consumption and engine noise.  With the help of installed hydraulic compensators, engine noise is reduced, valves do not need adjustment. It is recommended to replace the timing chain belt every 250000 kilometers.

Stable idling speed is achieved by the throttle valve with the help of automatic control and correction of data on the advance of the ignition mechanism.
The throttle sensor, which regulates the throttle at idle, is coordinated by the idle solenoid valve. In the event of its failure, it should only be adjusted or replaced by the manufacturer’s service center.

BMW recommends the use of AI-95 gasoline. Original synthetic motor oil 5w-30, 5w-40 to 10w-40 and 15w-40 depending on the time of year, brake fluid DOT 4 and the original from the manufacturer of coolant or antifreeze brand “Tosol”, “Nord” will support flawless operation of the motor.
The average consumption of gasoline per 100 kilometers will be from 6.7 to 11.2 liters, engine oil with filter 1 liter, coolant 5 liters and brake fluid 1.2 liters. It is recommended to
change the engine oil every 7000 -10000 kilometers, and change the disposable filter at least once a year, but at the same time as the oil change. With a constant cycle with full oil filtration, engine lubrication is of the combined type and is controlled by a baroscope. In case of increased engine operation, the engine oil and filter should be changed according to the indications of the technical inspection. Brake fluid should be changed after one year and antifreeze every two years. Depending on the type of transmission, the manufacturer’s recommendation for use of oil for mechanics is SAE 75W-90, for automatic transmission G 052.

The power unit with proper care can increase its resource of more than 400000 kilometers.

The designers of the M50B20 power unit put in the markings of the following indicators: M – indicates the series family of the unit, the category of row and the number of cylinders – means the number 5, and 0 – notifies about the lack of changes in the basic version, well and the letter B indicates the type of fuel – gasoline and location within the family, in this case it means longitudinally or transversely.

Installation of the motor is designed on the front part of the car next to the front suspension longitudinally.
Vin code of the engine can be seen at the junction of the unit and the gearbox on the left side.
The M50B20 motor is installed on BMW third and fifth series cars, such as 320i E36 and BMW 520i E34 series, as it was produced for only five years.

Modifications

Let’s take a look at BMW’s M50 series engines.

M50 replaced the previous model of the M20 engine.
The main changes touched the engine cylinder head, the VANOS gas distribution mechanism was developed and implemented, a new control system was placed, the timing drive was replaced by its chain type. As a result, fuel costs were reduced, performance was increased, audibility and engine torque were improved. In the legendary M50 series, two varieties of power unit of different cubic capacity were produced. And although the engines of this series were considered a very successful development of the designers, they were also technically improved.

• From 1991 to 1992, the base powertrains of the first varieties were used – these were the 2-liter M50 B20 and the 2.5-liter M50 B25.
• From 1992 to 1995, their improved versions were introduced – these were the 2 liter M50 B20 TU and the 2.5 liter M50 B25 TU.

Five years later, this series was replaced by the M52 version of the internal combustion engine with an aluminum block and similar displacement.

Chip tuning and power increase

Every car owner would like to get additional power from the engine and feel instant results. At the same time, he believes that there will be no consequences from it. It is worth noting that the manufacturer does not install chip tuning because of the need to comply with strict parameters of the ecology of exhaust gases.

To increase power by 42 horsepower, you can simply replace the base model of the unit with an improved 2.5-liter M50B25.

You can increase the power of the already installed base model up to 2.6 liters and 200 horsepower by replacing a significant number of its components with new ones and parts from its more advanced brethren M50 B25 and M52B28. But, you need to be prepared for the fact that after the modernization of the engine can be used only gasoline not lower than AI-98, otherwise you can not avoid a drop in power and the occurrence of detonation.

You can also install ready-made stroker – kits or turbo – kit Garrett, in this case, the power of the native engine can be increased to 3 liters and up to 300-400 horsepower.

After a certain time after installing chip tuning, there are problems with malfunctioning injectors, burned out valves of the cylinder-head and recirculation of exhaust gases, as well as melted pistons. Everyone makes their own choice to modernize their car, but you should always keep in mind the consequences for it. After all, services to install chip tuning for some reason do not provide a warranty for cars with an impressive mileage or working with a heavy load

If you treat the car with care, change engine oil in time and only the recommended by the manufacturer, regularly undergo maintenance and change spare parts in time, you can easily increase the engine life up to 400 000 km and postpone the moment of engine overhaul.
Preventive inspection of the power unit can be carried out independently, but maintenance and repair is better to undergo in a specialized service.

This engine is installed on the following models:

BMW 3-Series (E36)

BMW 5-Series (E34)