BMW M50B20TU engine

M50B20TU- is a gasoline power unit from the Bavarian company, which is distinguished by a working volume of 2 liters, and provides 150 horsepower of maximum power. This motor can be found under the hood of the third generation BMW 5 series in the E34 body.

M50B20TU engine specifications

Advantages

The year 1992 was marked by a technical update of the standard M50B20 engine, which was equipped with a special Vanos system. This engine was named accordingly – M50B20TU. This system allows to provide dynamic control of camshafts, which in fact is a change of camshaft timing.

The application of such technology makes it possible to provide a more even graph of torque parameters. Traction from the engine also becomes stable regardless of the rpm range during operation. If we compare, the finalized version allows you to provide increased torque at low and high speeds, compared to the standard modification. This makes it possible to get good dynamics of the car, and also allows you to save fuel. Regardless of what the crankshaft speed will be, the motor will be more economical, more powerful and emit less harmful substances into the environment.

Bavarians use several VANOS systems – Mono and Double. The M50B20 motor uses a standard mono system, which is located on the intake, which provides a change in the opening phases of the intake valves. If you judge without special attention, you can draw certain parallels between this technology, and the well-known VTEC and i-VTEC from HONDA.

In purely technical terms, the Vanos-equipped M50B20TU is characterized by the ability to shift maximum torque to lower revs. Peak thrust is achieved at 4.2 thousand rpm. In the unmodified version, this figure is reached at 4.9 thousand rpm.

Therefore, if you have to choose between the two motor variants, you should buy the TU version. Since the torque is stabilized at low, medium and high revs, the powertrain is much more stable and economical, and the car responds better to the accelerator pedal and shows better dynamics.

Disadvantages

The BMWM50B20TU engine very often gives its owners problems with overheating. Motors are very prone to it, and also quite difficult to tolerate it. Therefore, if the engine starts to overheat, it is necessary to pay attention to what condition the water pump, thermostat and radiator are in. It is worth carefully inspecting the entire cooling system for plugs, as well as examine the integrity of the radiator cap.

The engine may be moving. It is necessary to check the condition of the ignition coils, most often the problems lie in this node. If no faults are detected, check the plugs and fuel injectors.

The engine very often shows uneven operation and floating revolutions. Most often, the idle valve failure is the cause of such problems. By cleaning the valve, you can solve the trouble. If this did not bring positive results, then you need to pay attention to the lambda probes, temperature sensor and throttle position sensor. You can also try cleaning the throttle valve.

A problem can also occur with the Vanos system. As a rule, the first sign of malfunction is loss of power and floating rpm accompanied by rumbling. The problem can be solved by purchasing and installing a repair kit.

Among other things, the engines are quite old, and taking into account their operating peculiarities, the motors are characterized by increased oil consumption – up to 1 liter per every thousand kilometers. After overhaul, this indicator is not significantly reduced.

Leaks can also be observed in the gasket area of the valve cover and sump, and leaks through the dipstick of the lubricant level cannot be ruled out. The probability of a crack in the expansion tank is also quite high, which leads to antifreeze leakage. Problems may also occasionally occur with the camshaft and crankshaft position sensors, coolant temperature and so on.

Despite the typical faults, the BMW M50B20TU engine has established itself as one of the most reliable motors produced by the Bavarian concern, and the main problems are caused by the age and peculiarities of using the power unit. The resource of the M50B20TU can exceed the figures of 400 thousand kilometers, and if it is adequately operated and serviced in a timely manner, such figures can surpass 400 thousand kilometers by large numbers.

Tuning

You can try to build a stroker based on the M50B20TU. It is no secret that a 2-liter motor can not please its owners with very high power. Therefore, many people decide to go to increase power without loss of resource. The easiest way is welding to M50B25. But you can try to increase the working volume of the standard engine to 2.6 liters, while using only parts from manufacturers.

First you will need to buy a crankshaft and mass air flow sensor from the M52B26, the connecting rods and pistons remain standard. Fuel injectors, throttle valve, and fuel pressure regulator will have to be purchased from the M50B25, as well as a customized electronic control unit. After that it will be possible to get a compression ratio of 12 to one, and the output is about 200 horsepower of maximum power. It is best to fill the tank with 98 gasoline to drive without problems.

In the case of the M50B20TU, which is equipped with a vanos, it is best to use the crankshaft and connecting rods from the M55B28. To get the most out of it you should install the intake manifold with throttle from the M50B25 motor. Also, don’t forget to port the cylinder head, align the ducts, and install an equal-length manifold equipped with the exhaust system from the M50B25. This will give more power gains, as well as increase the dynamic performance of the car with this motor under the hood.

Those who do not have enough of such indicators, you can try to build a stroker for 3 liters of working volume. To do this, you will need to bore the cylinders to 84 millimeters in diameter, as well as purchase pistons with rings, connecting rods with liners, and a crankshaft from the M54B30. The cylinder block will have to be machined to 1 millimeter. In addition to this, you will have to buy a cylinder head and liners from the M50B25 motor. Putting all the parts together, you can get a good three-liter motor.

In order to maximize output without the need for an additional supercharger, the standard camshafts will need to be replaced with Schrick 264/256 camshafts. A six-throttle intake will also have to be used, along with the injectors and MAP sensor from the S50B32 motor. The exhaust system is installed from a BMW S38. After proper tuning, you can get about 270 horsepower.

There is also the option of installing an additional supercharger in the form of a turbine. The easiest option is to buy a turbo kit based on a Garrett GT30 turbo with a turbo manifold, westgate, block-off, MAP-sensor, wideband lambda probe, boost controller, full intake, intercooler, 440 cc injectors and full exhaust. After that, proper tuning will help you get about 300 horsepower on a standard piston group.

Technical specifications

The M50B20 is the smallest inline six-cylinder power unit in the BMW M50 series. Production of the power unit began in 1990 as a replacement for the outdated M20B20 power unit.

The main innovation in this motor is the use of a new cylinder head with four valves per cylinder, which is driven by two camshafts, which also have hydraulic compensators for thermal clearances. The engines have camshafts with a 240/228 phase, 9.7/8.8 lift. The intake valves are 30 millimeters in diameter and the exhaust valves are 27 millimeters. The design is more advanced because a plastic intake manifold is used.

Siemens MS40.0 is used as the electronic control unit. Among other things, in this power unit, the belt drive of the timing mechanism has been replaced by a chain drive. The service life of the chain is about 250 thousand kilometers. The tamper switch has been replaced by a more reliable system – individual ignition coils.

The M50B20TU engine was produced from 1992 to 1996. It utilizes an inlet phase rotation system. A new connecting rod and piston group is used. The 228/228 camshafts provide a compression ratio of 11 to 1. Maximum output of 150 horsepower is reached at 5.9 thousand rpm. At 4200 rpm, a torque of 190 Nm is achieved.

This engine is installed on the following models:

BMW 5-Series (E34)