BMW M50B20 / M50B20TU engine

Characteristics of the M50V20 engine

Production	Munich Plant
Engine brand	M50
Release years	1990-1996
Block material	cast iron
Supply system	injector
Type	in-line
Number of cylinders	6
Valves per cylinder	4
Piston stroke, mm	66
Cylinder diameter, mm	80
Compression ratio	10.5 11(TU)
Engine volume, cc	1991
Engine power, hp / rpm	150/6000 150/5900(TU)
Torque, Nm/rpm	190/4700 190/4200(TU)
Fuel	95
Environmental regulations	Euro 1
Engine weight, kg	-
Fuel consumption, l/100 km (for E36 320i) - city - track - mixed.	11.2 6.7 8.6
Oil consumption, g/1000 km	up to 1000
Engine oil	5W-30 5W-40 10W-40 15W-40
How much oil is in the engine, l	5.75
Oil change is carried out, km	7000-10000
Operating temperature of the engine, hail.	~90
Engine resource, thousand km - according to the plant - on practice	- 400+
Tuning, HP - potential - no loss of resource	400+ 190-200
The engine was installed

Reliability, problems and repair of the BMW M50B20 engine

The smallest straight-six of the BMW M50 series (the family also included the M50B24,) was released in 1990 as a replacement for the outdated one. The main innovation here is the use of a new cylinder head with 4 valves per cylinder and two camshafts, as well as hydraulic lifters. Used camshafts with phase 240/228, lift 9.7/8.8. The diameter of the intake valves is 30 mm, exhaust 27 mm. The M50 used an intake manifold made of plastic, a more advanced design.
Bosch Motronic 3.1/Siemens MS40.0 control system.
Among other things, in the M50B20, the timing belt drive has given way to a more reliable chain drive, the service life of which is more than 250 thousand km, individual ignition coils, an electronic ignition system, new pistons, lightweight connecting rods 135 mm, piston compression height 42.8 mm are used instead of a distributor. Nozzles M50 - 154 cc.

In 1992, these M50 engines began to be equipped with a phase shifter on the intake shaft (Vanos) and the name of the new engines was changed to M50B20TU. These motors used new connecting rods, 145 mm long, and the piston compression height is now 31.64 mm.
Siemens MS 40.1 engine management system
These motors were used on BMW cars with the 20i index.
In 1994, the low-volume M50 was replaced by a new, more advanced one, with the same working volume.

BMW M50B20 engine modifications

1. M50B20 (1990 - 1992 onwards) - basic engine variation. Compression ratio 10.5, power 150 hp at 6000 rpm, torque 190 Nm at 4700 rpm.
2. M50B20TU (1992 - 1996 onwards) - Vanos system (inlet phase shifter) added, SHPG replaced, camshafts with phase 228/228, lift 9/9 mm, compression ratio 11, power 150 hp are used. at 5900 rpm, torque 190 Nm at 4200 rpm.

Problems and disadvantages of BMW M50B20 engines

In the area of ​​​​faults, the M50B20 engine is similar to the older 2.5-liter brother M50B25, you can find out more about the problems.

BMW M50B20 engine tuning

M50B20 Stroker

It's no secret that the 2.0-litre engine doesn't amaze with power, and many M50B20 owners don't mind adding more power without sacrificing much in terms of reliability. The easiest way would be to buy an engine for Swap. If we consider options for modifying the native engine, then the easiest option to increase the output is to increase the working volume to 2.6 liters, moreover, with standard BMW parts.
For this step, we need to buy a crankshaft and an air flow sensor from, stock connecting rods, buy pistons from M50TUB20. The injectors, throttle body, fuel pressure regulator and tuned ECU are taken from the M50B25. After these transformations, we get a compression ratio of ~ 12 and a power of about 200 hp, pour 98 gasoline and drive without problems, or put a thick cylinder head gasket and pour 95, as an option, you can remove 0.3 mm from the bottom of the piston and get by with a standard gasket.
If the engine is with vanos, then we put the crankshaft and connecting rods from M52B28, nozzles from M50B25.
In order for our new M50B26 engine to open up to its full potential, you need to buy an intake manifold and throttle from an M50B25, make a porting of the head, align the channels and install an equal-length exhaust manifold with a full exhaust from an M50B25 or a sports one. These modifications will allow the engine to breathe freely and the maximum power will increase significantly. The dynamic characteristics of a car with an M50B26 engine and all the above tuning will be significantly higher than a regular M50B25.
The next step could be the M50B20 Stroker 3.0. To get 3 liters of displacement, we need to bore the cylinders to 84 mm and buy pistons with rings, connecting rods with liners and a crankshaft from. The cylinder block is ground off by 1 mm. To this we buy a cylinder head, main bearings from M50B25, a timing chain with a tensioner and damper, as well as all gaskets and 250 cc injectors. After assembling all this on the basis of the M50B20 block, we will get a full-fledged M50B30 Stroker.
For maximum power without a turbo on an M50B30 Stroker, you need to ditch stock cams and buy Schrick 264/256 (or similar), 6 throttle intake, injectors and MAP sensor from S50B32, exhaust from . After tuning, we get about 250-270 hp, and sometimes more.

M50B20 Turbo

The easiest way to turbo an M50 is to buy a Garrett GT30 based turbo kit with a turbo manifold, wastegate, blow-off, MAP sensor, broadband lambda probe, boost controller, full intake, intercooler, 440cc injectors and full exhaust. In order for all this to go, it is necessary to tune the brain, at the output we will get about 300 hp. to the stock piston.
For more power, you need to replace the turbine with a Garrett GT35, injectors for 500 cc, stock pistons for CP Pistons with a compression ratio of 8.5, Eagle connecting rods, APR bolts, metal cylinder head gasket, tune up and get 400++ hp.

At one time, the M50 engine was a real favorite of BMW. He replaced the M20 engine in 1991. The new engine was developed in two variations - 2.0 and 2.5 liters. However, its “life” on the market turned out to be short-lived: the production of “fifties” was discontinued already in 1996, when a new modification with an aluminum block appeared - it was assigned the M52 index.

Device M50

The M50 engine was installed on the E34 and E36 models. In 1992, BMW engineers gave the M50 a new gas distribution system called VANOS. The main “feature” of the innovation was the intake camshaft, which made it possible to increase engine thrust at low and medium speeds without loss at high ones.

The design is a standard 6-cylinder engine, which turned out to be a cast-iron block with an aluminum head. However, compared to its predecessor, the M20, the BMW M50 was a rather impressive step forward: a 24-valve gas distribution system with two camshafts driven by a chain and valve actuation through hydraulic lifters. The ignition system has also undergone changes - it has become entirely electronic, the distributor was removed as unnecessary and an ignition coil was added to each candle.

The M50 became the most successful and reliable engines from BMW, so they got a further life - based on the M50, modifications such as the 3-liter M3e36 with a power of 240 hp were assembled. and Alpina B3 with 250 hp The last option was intended for the American market. The weight of the engine was about 136 kg.

M50 modifications

Engine modification	Cylinder diameter, mm	Piston stroke, mm	Volume, cm3	Compression ratio	Power, hp	Torque, Nm	Max. rpm
М50В20	80	66	1991	10,5:1	150 at 6000 rpm	190 at 4700 rpm	6500
М50В20TU VANOS	80	66	1991	11:1	150 at 5900 rpm	190 at 4200 rpm	6500
M50B25	84	75	2494	10:1	192 at 6000 rpm	245 at 4700 rpm	6500
M50B25TU VANOS	84	75	2494	10,5:1	192 at 5900 rpm	245 at 4200 rpm	6500

Flaws

Despite all the “luck” of the M50, it still turned out to be not ideal, like all “long” engines: with severe overheating, the gas joint loses its tightness, as a result of which cracks form on the cylinder head. Excessive oil consumption, which in normal operation is 1 liter per 1000 km, is already observed after 300-400 thousand kilometers. The consequences are sad - exhaust valves burn out, and in some cases, cracks form between them due to local overheating.

Many parts manufacturers install plastic parts in the water pump, which causes damage to the bearings and the pump impeller. Often, with low qualifications of the craftsmen, the result of the repair is incorrectly installed camshafts. The motors of the first years of production suffer from failures of the ignition coils and cases of burnout of the power keys that control the ignition. But the erosion of the liners is less common than in the 40 series motors. Many 50 series engines have oil leaks - under the gaskets of the pan, valve and front covers, at the connection of the cylinder block with the oil filter and the dipstick ring.

Some M50s suffer from cylinder shutdown, which in turn cuts off the fuel supply. To turn them on, it is often necessary not only to eliminate the malfunction, but also to clean the memory. But, at least, these systems do not suffer too much from breakdowns associated with a lambda probe - an oxygen sensor.

Advantages

The M50 has a number of differences from the first generation engines, which, of course, was a big step forward for BMW. It was this engine with its 4 valves per cylinder that founded the fashion for the “explosive” engines of the German auto giant, which has survived to this day.

The M50 was the last unit to use the “cast iron block and aluminum cylinder head” combination, which was a truly faithful and reliable design.

The M50 also set the popular standard of “1 Nm per 10 cm 3 cylinders”, which was unattainable in the engines of the old series. The engine perfectly adapted to 95 gasoline, which, however, cannot be said about the 2-liter versions - even such an octane number is not enough for them. But this problem is solved to some extent with the help of knock sensors. According to the results, despite its inherent shortcomings, the BMW M50 became the best in the history of the concern, both in terms of technical and consumer data.

The work of the BMW M50 engine (video)

Diesel engines type M-50 F-3 (12ChSPN 18/20)

Diesel M-50 F-3 (M-400) - four-stroke, V-shaped, twelve-cylinder, mechanically supercharged, high-speed marine engine with jet fuel spraying. Right hand and left hand models are available. A right-hand rotation diesel engine differs from a left-hand rotation diesel engine in the appearance of the reversing clutch, supercharger, sea water pump, exhaust system, as well as in the location of the fresh water pump units and the oil injection pump with a centrifuge. The arrangement of units on diesel engines of left and right rotation is mirror.

The M-50 F-3 diesel engine is designed to operate on high-speed hydrofoils. On the ship of the "rocket" type, one engine is installed, the "meteor" type - two and the "satellite" type - four engines. The diesel engine is equipped with reversible clutches, consisting of friction and gear clutches and ensuring the transmission of rotation from the diesel crankshaft to the propeller shaft (forward), disengagement of these shafts (idle) and change in the direction of rotation of the propeller shaft (reverse).

The operating power of the forward stroke can vary depending on the purpose within 368-736 kW with a corresponding change in the number of revolutions of the shaft within 1200 - 1640 rpm, the maximum reverse power is 184 kW at 750 rpm and the duration of operation is not more than 1 hour .

The diesel crankcase is cast from aluminum alloy and consists of two parts. In the upper bearing part there are seven seats of main bearings with liners in which the crankshaft rotates. Split steel liners are filled with lead bronze and bored along the shaft necks. The working surface of the liners is covered with a lead-tin alloy. The 60° angled flats on the top of the crankcase accommodate two six-cylinder blocks.

The crankshaft is made of alloy steel subjected to nitriding. It has six knees

in pairs in three planes at an angle of 120° to each other. The connecting rod and main journals are connected by round cheeks. A spring damper is attached to the rear flange of the crankshaft, which reduces the unevenness of the torque under variable loads. Six main and six trailer connecting rods are hung on the diesel crankshaft.

I-section connecting rods are made of alloy steel.

The upper heads of the main and trailer connecting rods are the same and have tin bronze bushings pressed into them. The lower head of the main connecting rod is detachable: the cover is attached to the main connecting rod with a wedge with two conical pins. A steel, lead-bronze-filled liner, consisting of two halves, is installed in the lower head of the main connecting rod. The trailer connecting rod is connected to the main connecting rod by means of a pin pressed into the eye of the main connecting rod.

Piston - stamped aluminum alloy. The piston crown is shaped like a Hesselmann combustion chamber. The piston has grooves in which four piston rings are installed, of which two (upper) are compression rings, and the rest are oil scraper rings. Gas distribution valves are located in the four recesses of the piston bottom. The piston pin is made of alloy steel, hollow, with a hardened outer surface, pressed into the piston bosses.

The cylinder blocks are six-cylinder, mounted on the upper crankcase of the diesel engine and attached to it with anchor studs. Each cylinder block consists of a jacket, six cylinder liners and a head. In the upper part, the bushing has a shoulder, with which it rests on the surface of the undercut in the block jacket. The lower belt of the cylinder sleeve is sealed with five rubber rings: four serve to seal the water cavity, and the fifth (lower) prevents oil from seeping out of the cavity of the upper crankcase.

Rice. 1. Diesel M-50F-3

Diesel engines of the M-400 type have two six-cylinder monoblocks (the head is cast integrally with the cylinder block). Six cylinder bushings are pressed into the monoblocks, each of which is a connection of two pipes: the inner one is made of alloy steel and the outer one is made of carbon steel. The working surface of the inner tube is nitrided.

The gas distribution mechanism is driven from the crankshaft by means of an inclined gear located in front of the diesel engine. Each cylinder has four valves - two intake and two exhaust. The valve is pressed against the seat by three coil springs. On each head of the block there are two camshafts, the cams of which directly act on the valve plates, interconnected by cylindrical gears.

The order of operation of the cylinders on a right-hand rotation diesel engine: 1l-6pr-5l-2pr-3l-4pr-6l-1pr-2l-5pr-4l-3pr; on diesel engine of left rotation: 1pr-6l-4pr-3l-2pr-5l-6pr-1l-3pr-4l-5pr-2l.

Fuel system. From the supply tank, through the filter, the fuel enters the fuel priming pump, from which, under a pressure of 2-4 bar, it is supplied through two parallel-connected fuel filters to the high-pressure fuel pump and to the injectors.

The fuel pump is twelve-plunger, with a double-sided cut-off and with separate suction and cut-off. Plunger diameter - 13 mm, plunger stroke - 12 mm. Fuel supply pressure 700-1000 bar. The order of operation of the pump plungers, counting from the end of the shaft on the drive side, is as follows: 2-11-10-3-6-7-12-1-4-9-8-5.

The diesel regulator is all-mode, indirect action, with an elastically connected cataract. Provides stability of speeds in the range from 500 to 1850 rpm.

Nozzle - closed type, with a hydraulically controlled needle. The nozzle atomizer has eight atomizing holes with a diameter of 0.35 mm, located so that when the fuel is sprayed, a cone with an angle at the top of 140 ° is formed. The fuel injection pressure of 200 bar ensures that the fuel is atomized into tiny particles evenly distributed throughout the entire volume of compressed air in the combustion chamber.

From the very beginning, the BMW M50 engine was produced in two types: 2.0 liters and 2.5.

In the 91st year, the M50 replaced the . It was produced for a relatively short time, somewhere before 96, because thanks to the modification with an aluminum block, which was introduced in 1994, it received the M52 brand.

BMW M50 engine device

The M50 was installed from 1991 on the e34 model until the end of its release in this body, as well as on the e36 from the beginning to the 94th year. On the M50, in 92, a gas distribution system was installed, which was called VANOS. The novelty was equipped only with an intake camshaft, which increased the engine thrust at medium and low speeds, while not losing them at high ones.

The design is nothing special, a six-cylinder engine with a cast-iron block and an aluminum block head. Compared to the M20, from a technical point of view, it has stepped far ahead. The variable valve timing system was 24-valve with two camshafts and driven directly through hydraulic lifters. The camshafts drove the chain. And this means a fully electronic ignition system without a distributor (each spark plug has an ignition coil).

On the basis of the M50, engines for the M3e36 with a capacity of 240 horses and a volume of 3.0 liters were assembled. and for Alpina B3 - 250 "horses" from 3.0 liters. (model for the American market). The motor weighs approximately 136 kg (average weight).

Malfunctions of BMW M50 and M50tu engines

BMW M50 and M50tu engines proved to be the most reliable and successful motors of the automaker. However, with strong overheating, it is distorted, the tightness of the gas joint is broken, and cracks form on the cylinder head. Excessive oil consumption, which is approximately 1 liter. per 1000 km (with proper operation), starts after 300-400 thousand km. mileage, and is often the cause of exhaust valve burnout, which, in some cases, may be accompanied by cracks formed between the valve seats.

There are manufacturers producing water pumps with an impeller made of plastic, which often leads to the destruction of bearings and seal failure, as well as the destruction of the impeller itself. Also during the repair - incorrect installation of camshafts, as a result of illiterate actions of the staff. On older engines, you can often find failure of the ignition coils, burnt out power ignition keys. When compared with the 40 series, the destruction of the liners is an order of magnitude lower. A very common phenomenon is considered to be the connection of the cylinder block with the oil filter glass, from under the pan gaskets, valve cover, front cover, as well as along the dipstick ring.

For BMW M50 and M50TU engines with a DME electronic control unit and for MS 40 and MS 40.1, it happens that the fuel supply is turned off, i.e. cylinders are deactivated. In addition to repair, to turn on the cylinders, it is also necessary to clean the memory. Usually these systems easily withstand breakdowns associated with.

Compared to systems such as Motronic 3.1 and 3.3 (manufactured by Bosch), which are sensitive to DC malfunctions, SIEMENS ECUs are generally difficult to repair. BOSCH 413 (M 3.3.1) is also not very maintainable. In copies of the M50TU, which were produced before the 94th year, there is a rumble of the BMW VANOS system. It is eliminated by simply replacing parts of the system with similar, but narrower designs, which were released after the 94th year.

E34, they are looking at instances with m50 series engines, but why are these engines so good and how do they fundamentally differ from the engines of the previous series - m20? Like the m20, the m50 engines are in-line "sixes", but the new engines received two camshafts and a 24-valve cylinder head, in addition, the timing drive of the m50 engine is chain, not belt. The new gas distribution mechanism in the case of c made it possible to increase engine power by 22hp, but this is not the only thing, the modified intake and better purge of the combustion chamber allowed the engines of the new series to spin up faster than the engines of the previous series did. In addition, the fiftieth motors do not require adjustment of thermal gaps - they are equipped with hydraulic compensators. The new engines have a fully electronic ignition system, without a distributor and with six ignition coils - one coil for each cylinder.

On the E34, the m50 engine is known from the 520 and 525 models, on which the "fiftieth" engines were installed from 1991 until the E34 was discontinued in 1995. In 1993, the engines of the fiftieth series were modified, they received the Vanos system, which, by shifting the intake camshaft, made it possible to reach maximum torque 500 rpm earlier than was possible with a non-vanos engine. Which motor is better - with or without Vanos? There is a lot of controversy on this topic, but in most cases people agree that those are not so significant advantages that this system gives, does not justify all the problems that occur during its operation, and in fact the power and thrust of these engines are the same, I repeat - the whole difference is that the m50tu (this is how the engine with Vanos is designated) reaches maximum torque 500 rpm earlier, it reaches maximum traction at 4,200 rpm, while the driver of a car without Vanos gets maximum traction under the pedal at 4 700 rpm - this also applies to the 520th and 525th models. It is quite simple to visually distinguish between a Vanos and a non-Vanos unit: if a Vanos-free installation does not have any protrusion in the intake camshaft area, then on a car with Vanos there is a certain rounding in that place, which indicates the presence of a gas distribution mechanism under it - pay attention to the photo, the m50 without Vanos is shown on top .

Let's compare the characteristics of vaned and non-vaned engines.

The M50b20 engine with a cylinder diameter of 80mm and a piston stroke of 66mm has a volume of 2.0 liters. The compression ratio of the non-vanous b20 is 10.5: 1, the compression ratio of the vaned unit is 11.1: 1, that is, this engine is more picky about the quality of gasoline. The power of both units is 150hp, the maximum torque is 190N.M, in the vaned version it is achieved at 4,200, in the non-vaned version at 4,700 rpm.

The larger m50 b25 engine with a cylinder diameter of 84mm and a piston stroke of 75mm has a volume of 2.5 liters. In addition to the volume from the b20 installation, it differs in a more developed intake. The compression ratio of the non-vaned b25 is 10:1, in the vaned version, the b25 is 10.5:1 - in both cases, the compression ratio is not too high, so the car runs normally on 95th gasoline. Power - 192hp, torque - 245N.M - the same for both modifications. As with the b20, maximum torque is reached at 4,700 and 4,200 rpm, respectively.

The engine block is made of cast iron, and the cylinder head is made of aluminum. When overheated, the m50 head not only leads, but cracks between the valve seats are also possible.

The fiftieth motor was replaced by the M52 series unit, the main difference of which was the aluminum block, but this motor was no longer as reliable as its predecessor.

If you have owned a BMW with a 50 series engine, below you can leave your review about this power unit.