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)

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.

BMW M50B25 / M50B25TU engine

Characteristics of the M50V25 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	75
Cylinder diameter, mm	84
Compression ratio	10.0 10.5(TU)
Engine volume, cc	2494
Engine power, hp / rpm	192/5900 192/5900(TU)
Torque, Nm/rpm	245/4700 245/4200(TU)
Fuel	95
Environmental regulations	Euro 1
Engine weight, kg	~198
Fuel consumption, l/100 km (for E36 325i) - city - track - mixed.	11.5 6.8 8.7
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	1000+ 200-220
The engine was installed

Reliability, problems and repair of the BMW M50B25 engine

In 1990, the popular straight-six was replaced by a new, much more advanced and powerful one, called the BMW M50B25 (popularly nicknamed "Stove"), from the new M50 family (the series also included, M50B24,). The main difference between the M20 and M50 engines lies in the cylinder head, in the new engine the head was replaced with a more advanced two-shaft, 24-valve with hydraulic compensators (valve adjustment does not threaten). The diameter of the intake valves is 33 mm, exhaust 30.5 mm. Used camshafts with phase 240/228, lift 9.7/8.8 mm. And also used an improved lightweight intake manifold.
Bosch Motronic 3.1 engine management system.
The timing drive in the new M50 engines has also changed, now a chain is used instead of a belt, the service life of which is 250 thousand km (usually it runs longer). In addition, individual ignition coils, an electronic ignition system, other pistons, lightweight connecting rods 135 mm long are used. Nozzle size M50B25 - 190 cc.
Since 1992, M50 engines have received the well-known variable valve timing system on the Vanos intake shaft, and such engines have become known as M50B25TU (Technical Update). In addition, these engines use new connecting rods with a length of 140 mm and pistons with a compression height of 32.55 mm (38.2 mm on the M50B25).
The control system has been replaced with Bosch Motronic 3.3.1.
These power units were used onBMW cars with index 25i.
Since 1995, the M50V25 engine has been replaced by a new improved engine, and in 1996 the production of the M50 series was completed.

BMW M50B25 engine modifications

1. M50B25 (1990 - 1992 onwards) - base engine. Compression ratio 10, power 192 hp at 5900 rpm, torque 245 Nm at 4700 rpm.
2. M50B25TU (1992 - 1996) - a system for changing the valve timing on the Vanos inlet has been added, the connecting rod and piston group has been changed, other camshafts have been installed (phase 228/228, lift 9/9 mm). Compression ratio 10.5, power 192 hp at 5900 rpm, torque 245 Nm at 4200 rpm.

Problems and disadvantages of BMW M50B25 engines

1. Overheating. The M50 engine is prone to overheating and tolerates it quite hard, so if the engine starts to warm up, check the condition of the radiator, as well as the pump and thermostat, the presence of air pockets in the cooling system and the radiator cap.
2. Troit. Check the ignition coils, most often the problem is in them, as well as candles and nozzles.
3. Swim speed. Often the malfunction is caused by a failed idle valve (IAC). Cleaning will help bring the motor to life. If the problem persists, then look at the throttle position sensor (TPS), temperature sensor, lambda probe, clean the throttle.
4. M50 Vanos. The problem is expressed in rattling, loss of power, swimming speed. Repair: purchase of a vanos M50 repair kit.
In addition, due to their age and operating characteristics, BMW M50 engines suffer from high oil consumption (up to 1 liter per 1000 km), which does not decrease too much after overhaul. Valve cover gaskets and pan gaskets may leak, and leaks through the oil dipstick are not ruled out. The expansion tank also likes to crack, after which we get an antifreeze leak. At the same time, sensors of the M50 camshaft, crankshaft (DPKV), coolant temperature, and so on, periodically cause problems.
Despite everything, the BMW M50B25 engine is one of the most reliable power units of the Bavarian manufacturer, and most of the problems are caused by the age and style of operation of the motor. And even such engines roll over 300-400 thousand km, and if the motor was used sparingly and adequately maintained, then its resource can far exceed 400 thousand km, because it is not in vain that they received a reputation of millionaires.
Buying an M50B25 engine is a good choice for a swap and subsequent refinement with a turbocharger. Let's talk about these solutions next.

BMW M50B25 engine tuning

Stroker. camshafts

The easiest and fastest option to increase power using factory components is to install a long-stroke crankshaft (stroker). In M50B25 (Without vanos), the knee rises from with a stroke of 89.6 mm. From the same motor, you need to buy connecting rods, connecting rod bearings, repair pistons, injectors, and main bearings from the M50.
We assemble (you can leave the firmware stock, but it’s better to tune in) and drive a 3-liter M50B30, with a capacity of about 230 hp and a compression ratio of 10.
The same horsepower can be obtained by buying Schrick 264/256 camshafts and adjusting the Motronic stock. As a result, we get 220-230 hp. Let's buy a cold air intake, a sports exhaust and get 230+ hp.
The same camshafts on the M50B25 3.0 stroker will give about 250-260 hp.
To get maximum power from the M50B30, you need to buy Schrick 284/284 camshafts, a six-throttle intake, injectors from a BMW S50, a lightweight flywheel, make a cylinder head porting, buy an equal-length exhaust manifold and a straight-through exhaust. After tuning, such an M50B30 develops about 270-280 hp.
If this is not enough, you can bore the block for pistons 86.4 mm from S50B32 and get a displacement of 3.2. We buy camshafts and get about 260 hp.
Vanosny M50B25 can be converted into a 2.8 liter engine by installing a crankshaft with a stroke of 84 mm and connecting rods from M52B28. Together with the SIEMENS MS41 firmware, this will give +/- 220 hp, compression ratio ~11.

M50B25 Turbo

In the case when there is little atmospheric engine or the cost of its implementation is too high, you can organize a turbo version on a 2.5-liter engine. If tuning is supposed to be budget, then a Chinese turbo kit based on the Garrett GT35 (or another, with brains included) is your choice. Alternatively, you can find a used TD05 turbine (or another), weld a manifold, assemble all the piping, clamps, boost controller, intercooler, and so on. Put everything on the stock piston, pre-installing a thick Cometic cylinder head gasket, 440 cc injectors, Bosch 044 fuel pump, exhaust on a 3″ pipe, EFIS 3.1 brain (or Megasquirt), adjust and at 0.6 bar we get about 300 hp. At 1 bar ~400 hp
Something similar can be built by purchasing an M50 kit compressor and installing it on a piston drain. The output from the compressor will be noticeably lower than that of the turbine.
Even more power can be obtained by buying and installing a turbo kit on the original Garrett GT35, CP Pistons for 8.5 compression, Eagle connecting rods, ARP bolts, performance injectors (~550 cc). With such kits, you can increase the power to 500++ hp. Similar projects can be built on a 3-liter stroker.

Reliability, problems and repair of the BMW M50B25 engine

In 1990, the popular straight-six BMW M20B25 was replaced by a new, much more advanced and powerful one, called the BMW M50B25 (popularly nicknamed the “Slab”), from the new M50 family (the series also included M50B20, M50B24, S50B30, S50B32 ). The main difference between the M20 and M50 engines lies in the cylinder head, in the new engine the head was replaced with a more advanced two-shaft, 24-valve with hydraulic compensators (valve adjustment does not threaten).

The diameter of the intake valves is 33 mm, exhaust 30.5 mm. Used camshafts with phase 240/228, lift 9.7/8.8 mm. And also used an improved lightweight intake manifold. Bosch Motronic 3.1 engine management system. The timing drive in the new M50 engines has also changed, now a chain is used instead of a belt, the service life of which is 250 thousand km (usually it runs longer). In addition, individual ignition coils, an electronic ignition system, other pistons, lightweight connecting rods 135 mm long are used. Nozzle size M50B25 - 190 cc.

Since 1992, M50 engines have received the well-known variable valve timing system on the Vanos intake shaft, and such engines have become known as M50B25TU (Technical Update). In addition, these engines use new connecting rods with a length of 140 mm and pistons with a compression height of 32.55 mm (38.2 mm on the M50B25).

The control system has been replaced with Bosch Motronic 3.3.1. These power units were used on BMW cars with the 25i index. Since 1995, the M50V25 engine has been replaced by a new improved M52V25 engine, and in 1996 the production of the M50 series was completed.

BMW M50B25 engine modifications

• M50B25 (1990 - 1992 onwards) - base engine. Compression ratio 10, power 192 hp at 5900 rpm, torque 245 Nm at 4700 rpm.
• M50B25TU (1992 - 1996 onwards) - a system for changing the valve timing on the Vanos intake was added, the connecting rod and piston group was changed, other camshafts were installed (phase 228/228, lift 9/9 mm). Compression ratio 10.5, power 192 hp at 5900 rpm, torque 245 Nm at 4200 rpm.

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	75
Cylinder diameter, mm	84
Compression ratio	10.0 10.5(TU)
Engine volume, cc	2494
Engine power, hp / rpm	192/5900
Torque, Nm/rpm	245/4700 245/4200(TU)
Fuel	95
Environmental regulations	Euro 1
Engine weight, kg	198
Fuel consumption, l/100 km (for 320i F30) - city - track - mixed.	11.5 6.8 8.7
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
When replacing pour, l	4
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	1000+ 200-220 -
The engine was installed	BMW 325i E36 BMW 525i E34

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.