Concern BMW (Bayerische Motoren Werke) - one of the world's largest manufacturers of cars and motorcycles. However, the production of internal combustion engines is far from the last in the structure of its production. Suffice it to say that the line of power units manufactured by the concern includes both gasoline and diesel:
- BMW IN-LINE ENGINES (RANGE M)
In the automotive powertrain market, the most famous in-line six-cylinder engines of the BMW concern. Various engine modifications of the M model range have been installed on BMW 3 and 5 Series vehicles in different years:
m10 (1962-1988), m20 (1977-1987), m40 (1988-1994), m50 (1990-1995), m52 (1994-2001), m54 (2001-2006).
In 2005, the M engines were replaced by a new generation of BMW engines - the N series. Its first representative was the N52 engine.
- M50 SERIES ENGINES
In Soviet times, the purchase of a BMW car was a pipe dream of every motorist. However, during the times of "perestroika", many managed to realize their dream? and on domestic roads these previously inaccessible models appeared in a fairly large number.
It was at this time that the BMW concern massively produced and installed on its cars engines of the M model range, the technical characteristics of which were many times higher than the parameters of domestic automobile engines.
Specifications
M50b25 engine:
| PARAMETER | VALUE |
|---|---|
| Working volume of cylinders, cu. cm | 2494 |
| Rated power, hp from. (at 5900 rpm.) | 192 |
| Maximum torque, Nm (at 4700 rpm.) | 245 |
| Number of cylinders | 6 |
| Number of valves per cylinder, pcs. | 4 |
| The total number of valves, pcs. | 24 |
| Cylinder diameter, mm | 84 |
| Piston stroke, mm | 75 |
| Compression ratio | 10...10,5 |
| Cylinder operation diagram | 1 - 5 - 3 - 6 -2 - 4 |
| Fuel | Unleaded gasoline AI-95 |
| Fuel consumption, l / 100 km (city / mixed / highway) | 11,5/8,7/6,8 |
| Lubrication system | Combined (spraying + under pressure) |
| Engine oil type | 5W-30, 5W-40, 10w-40, 15W-40 |
| The amount of engine oil, l | 5.75 |
| Cooling system | Liquid, closed type with forced circulation |
| Coolant | Ethylene glycol based |
| Motor resource, thousand hours | 400 |
| Weight, kg | 198 |
The engine was installed on cars produced by the BMW concern: 3 series - BMW 320 E36, 325i E36; 5 series - BMW 520 E34, 525i E34.
Description
The beginning of the M lineup was laid by 4-cylinder engines of the M10 series with a volume of 1.5 ... 2.0 liters. The high technical characteristics of various modifications of these motors were largely due to the use of:
- two carburetors;
- fuel injection;
- turbocharging.
Design features of the M10 series motors:
- The cylinder diameter is greater than the piston stroke.
- The number of main bearings is 5.
- The intake and exhaust manifolds are located on opposite sides of the power unit.
- The cylinder block housing is made of cast iron and its head is made of aluminum.
NOTE: All M Series engines use a cast iron cylinder block + aluminum head combination. Only on engines of the N52 series did this pair begin to be made from a magnesium-aluminum alloy.
At the end of 1988, on the basis of the M10 engine, a new series of 4-cylinder engines was developed, which received the m40 index. Structurally, it was distinguished by the presence of:
- hydraulic valve lifters;
- of the belt drive of the gas distribution mechanism (GRM) SOHC.
The BMW m40 series engines had:
- higher power;
- increased torque in the area of \u200b\u200blow and medium rotational speeds of the crankshaft;
- less weight;
- reduced overall dimensions.
However, the power of 4-cylinder engines for heavy BMW cars was sorely lacking. Therefore, the company's management in the mid-60s decided to develop a model range of power units with 6 cylinders and seven crankshaft bearings.
It began with the M30 family of in-line engines with a cylinder volume of 2.5 to 3.5 liters. Despite the high technical parameters, these engines had a number of disadvantages, among which the main ones were heavy weight, significant dimensions and high cost.
In 1977, having begun to develop more modern, highly efficient and low-cost cars, the engineers of the concern created a number of new modifications of 6-cylinder engines based on the M30.
The first of them was a series of M20 motors with 2 valves per cylinder and a SOHC timing belt drive. The power units of this series were replaced by the m50 series motors, each of which is an in-line 6-cylinder gasoline engine, which, unlike its predecessor, has 4 valves per cylinder and two camshafts (DOHC system) with valve hydraulic lifters.
In addition, in engines of the m50 series, the timing chain is driven by a chain, the service life of which is at least 250 thousand kilometers. The presence of hydraulic valve lifters, which eliminate the need to adjust the latter, and the "unkillable" timing chain have greatly simplified the maintenance of these power units.
In addition, in 1992, the engines of this family received a new variable valve timing system Vanos (Technical Update), developed by BMW.
The system allowed:
- Increase torque at low engine speeds.
- Reduce fuel consumption.
Installation of the Vanos system required replacement:
- parts of the connecting rod and piston group;
- camshafts;
- electronic control unit (ECU).
Later the Vanos system underwent a number of changes. So, on the N52 engine, a more advanced variable valve timing system on two Double Vanos shafts was installed.
Maintenance
Regular maintenance of the m50 series motors is reduced to the timely replacement of engine oil.
The regulatory documents of the concern recommend changing the oil every 15,000 km, however, taking into account the condition of our roads and the quality of the fuel, the specialists of domestic service stations advise to carry out this procedure after 7,000 km. In this case, it is necessary to ensure that the engine oil to be filled has a BMW LL-98 or LL-01 approval.
Malfunctions
The m50b25 engines are considered one of the most reliable engines produced by the BMW concern. However, they, especially after the mileage exceeds 200 thousand km, are characterized by a number of common malfunctions.
| FAULTS | CAUSES |
|---|---|
| The engine runs unstable. | May be faulty: 1. Ignition coils. 2. Spark plugs. 3. Nozzles. 4. Idle valve. 5. Sensors for throttle position, temperature, lambda probe. |
| Loss of power. | The Vanos gas distribution system is out of order. |
| The engine is overheating. | Possible failure: Ÿ thermostat; Ÿ cooling system pump (pump); Ÿ radiator. |
| Increased consumption of engine oil. | Check the valve cover and sump gaskets for oil leaks. |
Tuning
Unlike the engines of the N52 series, which are practically not amenable to tuning, the motors of the M series can be modified independently. For example, there are several tuning options with which you can increase the power of the M50b25 engine:
- The easiest way is to install a long-stroke crankshaft (stroker), which was installed in the m54b30 engine. At the same time, it is necessary to purchase and install a number of parts of this power unit: connecting rod-piston group; nozzles; root liners. By adjusting the ECU accordingly, you can get a power of about 230 liters. from.
- The maximum power without using a turbine can be obtained by installing: Schrick 284/284 camshafts; injectors from the S50 sports engine; six-throttle inlet; equal length exhaust manifold; direct-flow exhaust system, etc. Correct adjustment of the ECU will bring the engine power up to 280 hp. from.
- If you set a goal to increase the engine power to 500 hp. with., then this can be done by installing on it: turbo kit with Garret GT 35; connecting rod and piston group for a compression ratio of 8.5; injectors 550 cc.
Engines of the M50 series were produced from 1990 to 1996. Their predecessor was the M20 engine range. Their cylinder block is made of steel and contains six straight cylinders. The cylinder head is cast from light alloy, which has two camshafts and four valves per cylinder (DOHC) compared to its single-shaft predecessor. A number of motors in the series in 1993 received the VANOS variable valve timing system, which controls the rotation of the intake camshaft.
It is noteworthy that the legendary BMW M3 in the back of the E36 was equipped with the S50 engine, built on the basis of the M50 series.
The two-liter version of the M50 engine, produced since 1990, which took its place in 1990 with the 520i and a year later with the 320i. The cylinder diameter is 80 mm and the piston stroke is 66 mm. As a result, the engineers managed to get a power equal to 150 hp.
- 1991-1992 BMW 320i (E36 body)
The same two-liter version of the engine, but received in 1993 the VANOS variable valve timing system. As a result, the maximum torque began to come 500 less than its predecessor M50b20, namely at 4200 rpm.
The engine was installed on cars:
- 1990-1992 BMW 520i (E34 body)
- 1991-1992 BMW 320i (E36 body)
This engine is quite rare, structurally similar to the M50B25, but with a reduced piston stroke. Its cylinder capacity is 2.4 liters. This unit has been specially designed for Thailand. It was only used in BMW 3 and 5 Series vehicles.
The engine was installed on cars:
- BMW 525i (E34 body)
- BMW 325i (body E36)
This engine first debuted in 1990 on BMW 525i and 525ix cars. Its working volume is 2494 cubic meters. cm. Bore 84 mm, piston stroke 75 mm. The engine develops 189 hp. at 5900 rpm, and the peak torque falls at 4700 rpm and is 245 Nm.
BMW M50B20 / M50B20TU engine
Characteristics of the M50V20 engine
| Production | Munich plant |
| Engine brand | M50 |
| Years of release | 1990-1996 |
| Cylinder block material | cast iron |
| Supply system | injector |
| A type | inline |
| Number of cylinders | 6 |
| Valves per cylinder | 4 |
| Piston stroke, mm | 66 |
| Cylinder diameter, mm | 80 |
| Compression ratio | 10.5
11 (TU) |
| Engine displacement, cubic cm | 1991 |
| Engine power, hp / rpm | 150/6000
150/5900 (TU) |
| Torque, Nm / rpm | 190/4700
190/4200 (TU) |
| Fuel | 95 |
| Environmental standards | Euro 1 |
| Engine weight, kg | - |
| Fuel consumption in l / 100 km (for E36 320i) - city - track - mixed. |
11.2 6.7 8.6 |
| Oil consumption, gr. / 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 |
| Engine operating temperature, deg. | ~90 |
| Engine resource, thousand km - according to the plant - on practice |
- 400+ |
| Tuning, hp - potential - without loss of resource |
400+ 190-200 |
| The engine was installed | |
BMW M50B20 engine reliability, problems and repair
The smallest inline-six of the BMW M50 series (the family also includes 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. Camshafts with a phase of 240/228, lift 9.7 / 8.8 are used. Diameter of inlet valves is 30 mm, outlet valves are 27 mm. The M50 has an intake manifold made of plastic, of a more perfect design.
Bosch Motronic 3.1 / Siemens MS40.0 control system.
Among other things, in the M50B20 the timing belt drive gave way to a more reliable chain drive, the service life of which is more than 250 thousand km, instead of a distributor, individual ignition coils, an electronic ignition system, new pistons, light rods 135 mm, compression piston height 42.8 mm are used. M50 nozzles - 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 engines used new connecting rods, 145 mm long, and the compression height of the piston is now 31.64 mm.
Siemens engine management system MS 40.1
These motors were used on BMW cars with a 20i index.
In 1994, the low-volume M50 was replaced by a new, more advanced one, with the same displacement.
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) - added the Vanos system (phase shifter at the inlet), replaced the ShPG, used camshafts with a phase of 228/228, lift 9/9 mm, compression ratio 11, power 150 hp at 5900 rpm, torque 190 Nm at 4200 rpm.
BMW M50B20 engine problems and malfunctions
In the area of \u200b\u200bmalfunctions, the M50B20 engine is similar to the older 2.5-liter brother M50B25, you can learn more about the problems.
BMW M50B20 engine tuning
M50B20 Stroker
It is no secret that the 2-liter engine does not impress with power and many owners of the M50B20 do not mind increasing the power without losing much in reliability. The easiest way is to buy a Swap engine. If we consider the options for modifying the native engine, then the easiest option to raise the recoil is to increase the working volume to 2.6 liters, with standard BMW parts.
For this step, we need to buy a crankshaft and an air flow sensor from, stock connecting rods, we 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 we 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 motor is with vanos, then we put the crankshaft and connecting rods from М52B28, injectors from М50B25.
To get our new M50B26 engine to its fullest, you need to buy an intake manifold and a throttle valve from an M50B25, make a head porting, align the channels and install an equal length exhaust manifold with 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 of the above tuning will be significantly higher than the usual M50B25.
The next step could be the M50B20 Stroker 3.0. To obtain 3 liters of displacement, we need to bore cylinders up to 84 mm and buy pistons with rings, connecting rods with liners and a crankshaft from. The cylinder block is ground down by 1 mm. In addition, we buy a cylinder head, main bearings from M50B25, a timing chain with a tensioner and a damper, as well as all gaskets and injectors of 250 cc. After assembling all this on the basis of the M50B20 block, we will get a full-fledged M50B30 Stroker.
To get maximum power without a turbine on the M50B30 Stroker, you need to throw out the stock camshafts and buy Schrick 264/256 (or other similar ones), 6 throttle inlets, injectors and MAP sensor from S50B32, exhaust from. After tuning, we get about 250-270 hp, and sometimes more.
M50B20 Turbo
The easiest option to turbo the 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, 440 cc injectors and full exhaust. For all this to go, it is necessary to tune the brain, the output will be about 300 hp. on the piston stock.
For more power, it is necessary to replace the turbine with a Garrett GT35, injectors for 500 cc, the stock pistons are replaced with CP Pistons with a compression ratio of 8.5, Eagle connecting rods, APR bolts, a metal cylinder head gasket, adjust and get 400 ++ hp.
At one time, the M50 engine was a true favorite of BMW. It 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 was short-lived: the production of “fifty” was discontinued in 1996, when a new modification with an aluminum block appeared - it was assigned the M52 index.
M50 device
The M50 engine was installed on the e34 and e36 models. In 1992, BMW engineers presented the M50 with 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 losses at high speeds.
The design is a standard 6-cylinder engine, which turned out to be a cast iron block with an aluminum head. Compared to its predecessor, the M20, however, the BMW M50 was a pretty impressive step forward: a 24-valve timing system with two chain-driven camshafts and valve actuation via 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 spark plug.
The M50 became the most successful and reliable engines from BMW, so they got further life - on the basis of the M50, modifications such as the 3-liter M3e36 with a capacity of 240 hp were assembled. and Alpina B3 with 250 hp. The latter option was intended for the American market. The engine weight was about 136 kg.
Modifications M50
| Engine modification | Cylinder diameter, mm | Piston stroke, mm | Volume, cm3 | Compression ratio | Power, h.p. | Torque, Nm | Max. rpm |
|---|---|---|---|---|---|---|---|
| M50V20 | 80 | 66 | 1991 | 10,5:1 | 150 at 6000 rpm | 190 at 4700 rpm, min | 6500 |
| М50В20TU VANOS | 80 | 66 | 1991 | 11:1 | 150 at 5900 rpm | 190 at 4200 rpm, min | 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 |
disadvantages
Despite all the “luck” of the M50, it turned out to be not ideal, like all “long” engines: with strong 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 observed after 300-400 thousand km of run. The consequences are sad - the exhaust valves burn out, and in some cases cracks form between them due to local overheating.
Many aftermarket manufacturers install plastic parts in the water pump, which causes damage to the bearings and pump impeller. Often, with low qualifications of the craftsmen, the result of repairs is incorrectly installed camshafts. Motors of the first years of production suffer from ignition coil failures and cases of burnout of the power keys that control the ignition. But the erosion of the liners is less common than that of the 40 series motors. Many engines of the 50 series 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 required not only to eliminate the malfunction, but also to clear the memory. But, at least, these systems do not suffer too much from breakdowns associated with the lambda probe - the 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 "explosive" engines of the German auto giant, which has survived to this day.
The M50 was the last unit to use a cast iron block and aluminum cylinder head combination, which was a truly reliable and reliable design.
The M50 also set the popular standard “1 Nm per 10 cm 3 cylinders”, which was unattainable in the older series engines. 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. As a result, despite its inherent shortcomings, the BMW M50 became the best in the history of the concern, both in terms of technical and consumer data.
BMW M50 engine operation (video)
In 1990, the popular inline-six BMW M20B25 was replaced by a new, much more advanced and powerful, called BMW M50B25 (popularly nicknamed "Stove"), from the new M50 family (the series also included M50B20, M50B24, S50B30, S50B32 ). The main difference between the M20 and M50 engines is the cylinder head; in the new engine, the head was replaced with a more advanced two-shaft, 24-valve with hydraulic compensators (valve adjustment is not threatened). The diameter of the intake valves is 33 mm, the exhaust valves are 30.5 mm. Camshafts with a phase of 240/228 are used, a lift of 9.7 / 8.8 mm. And also an improved lightweight intake manifold is used.
Bosch Motronic engine management system 3.1.
The timing drive in the new M50 engines has also changed, now instead of a belt, a chain is used, the service life of which is 250 thousand km (as a rule, it runs more). In addition, individual ignition coils, an electronic ignition system, other pistons, lightweight connecting rods with a length of 135 mm are used. The size of the M50B25 nozzles is 190 cc.
Since 1992, M50 engines have received the well-known Vanos intake camshaft timing system, and such engines have become known as the M50B25TU (Technical Update). In addition, these engines use new 140mm connecting rods and pistons with a compression height of 32.55mm (38.2mm on the M50B25).
The control system is replaced by Bosch Motronic 3.3.1.
These power units were used on BMW cars with an index of 25i.
Since 1995, the М50В25 engine began to be replaced by a new improved М52В25 engine, and in 1996 the production of the М50 series was completed.
Feature of the BMW M50 TU engine
The technical redesign of the M50 engine has led to the following improvements: improved behavior of torque changes, especially in the mid-speed range, reduced fuel consumption, improved idle performance with a simultaneous decrease in idle speed, improved exhaust characteristics (reduced emissions), improved acceleration, better engine acoustics, engine improvements M50TU (M50TU) relative to the M50 engine were achieved by the following design changes and measures: the use of digital motor electronics DME3.3.1 with anti-knock control in the 2.5-liter engine (M50TUB25) the use of the Siemens MS 40.1 engine controller in all E36 and E34 models with the M50TUB20 engine by increasing the compression ratio using the VANOS system by changing the crank mechanism (new pistons and connecting rods) by a new idle speed regulator in a 2.5-liter M50TUB25 (ZWD-5) engine using a thermofilm air flow meter m of valve stem diameter and the use of one valve spring using disc pushers and spring plates, optimized for masses by changing the valve acceleration characteristics by changing the crankshaft vibration damper
Characteristics of the M50V25 engine
| Production | Munich plant |
| Engine brand | M50 |
| Years of release | 1990-1996 |
| Cylinder block material | cast iron |
| Supply system | injector |
| A type | inline |
| Number of cylinders | 6 |
| Valves per cylinder | 4 |
| Piston stroke, mm | 75 |
| Cylinder diameter, mm | 84 |
| Compression ratio | 10.0 10.5 (TU) |
| Engine displacement, cubic cm | 2494 |
| Engine power, hp / rpm | 192/5900 192/5900 (TU) |
| Torque, Nm / rpm | 245/4700 245/4200 (TU) |
| Fuel | 95 |
| Environmental standards | Euro 1 |
| Engine weight, kg | ~198 |
| Fuel consumption in l / 100 km (for E36 325i) - city - track - mixed. | 11.5 6.8 8.7 |
| Oil consumption, gr. / 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 |
| Engine operating temperature, deg. | ~90 |
| Engine resource, thousand km - according to the plant - on practice | - 400+ |
| Tuning, hp - potential - without loss of resource | 1000+ 200-220 |
| The engine was installed | BMW 325i E36 BMW 525i E34 |
VANOS system
Both the power and exhaust characteristics and the driving behavior of the 4-stroke gasoline engine while driving can be significantly improved by the variable intake camshaft angle. VANOS in M50 engine The opening angle of the intake camshaft of the M50TU engine can be changed, i.e. taking into account the specific operating conditions, switch from late opening to earlier or vice versa. The advantages of the VANOS system are: high power and improved torque in certain speed ranges; reduced NOX and CH emissions in the partial load range; low residual gas at idle; due to this, on the one hand, an improved idle speed due to a more favorable mixture, and on the other hand, a lower fuel consumption due to a decrease in the idle speed. Improved idle acoustics Better engine response High functional safety Extensive self-diagnosis and trouble-free troubleshooting The VANOS shift system is controlled by the control unit of the corresponding digital motor electronics. In a 2-liter engine, a Siemens MS401 control unit, in a 2.5-liter engine, a Bosch M3.3.1 Motronic control unit.
VANOS design
For both the M50TU20 and M50TU25 engines, many tests were carried out with various variants of camshafts and opening angles to identify in each case the most advantageous variable opening angles of the intake camshaft. As a result, the following opening angles were selected: M50TU20 105º (late changeover) 80º (early changeover) M50TU25 110º (late changeover) 85º (early changeover) This implies for both engine variants the maximum changeover angle of the variable intake camshaft opening angle of 25º KW (crankshaft angle). Components: front helical intake camshaft; chain sprocket with an internal helical rim; a hydraulic-mechanical device for changing the camshaft with one hydraulic piston and a helical gear; solenoid 4/2-way changeover valve; connecting oil pressure line from the cylinder block to the 4/2-way valve; control and diagnostic electronics of the controller;
Modifications
1. M50B25 (1990-1992) - base engine. Compression ratio 10, power 192 HP at 5900 rpm, torque 245 Nm at 4700 rpm.
2. M50B25TU (1992 - 1996 onwards) - added a variable valve timing system at the Vanos intake, changed the connecting rod-piston group, installed other camshafts (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
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 plugs in the cooling system and the radiator cap.
2. Troitus. Check the ignition coils, most often the problem is in them, as well as the spark plugs and injectors.
3. Float turns. Often the malfunction is caused by a failed idle valve (KXX). Cleaning will help revive the motor. If the problem persists, then look at the throttle position sensor (TPS), temperature sensor, lambda probe, clean the throttle valve.
4. M50 Vanos. The problem is expressed in rattling, loss of power, swimming revs. 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 and pan gaskets may leak, leaks through the oil dipstick are not excluded. The expansion tank also likes to crack, after which we get antifreeze leakage. At the same time, the sensors of the M50 camshaft, crankshaft (DPKV), coolant temperature, etc., cause problems from time to time.
Despite everything, the BMW M50B25 engine is one of the most reliable power units of the Bavarian manufacturer, and the bulk of the problems are caused by the age and style of operation of the engine. And even such engines roll over 300-400 thousand km, and if the engine was used in a sparing mode and was adequately maintained, then its resource can go far beyond 400 thousand km, because it is not in vain that they have received a reputation of millionaires.
Buying an M50B25 engine is a good choice for swap and subsequent revision with a turbocharger. Let's talk about such decisions further.
Diagnostics M50TUB25 with DME M3.3.1
If there are no error messages in the memory, then the control signal is sent to the VANOS system when the M50TUB25 engine with DME M3.3.1 is running at idle speed. For this, two adapters are used - special BMW tools No. 61 2 050 and 61 1 467. If, at the same time, close the solenoid valve to ground, an engine with a working VANOS system will work extremely unevenly or completely stall.
Diagnostics M50TUB20 with MS40.1
The VANOS system is fully verified by self-diagnostics. The absence of error messages in the memory on the M50TUB20 engine with MS40.1 is a sign of complete serviceability of the VANOS system. Before checking the function of the MS40.1, the data from the fault memory must also be read. If there are no such messages, the VANOS system controlled by this controller can be checked with the tester. If the camshaft is switched to an early position while the engine is idling, then the power unit with a working VANOS system will operate extremely unevenly or completely stall (similar to the function test on an engine with DME M3.3.1).
BMW M50B25 engine tuning
Stroker. Camshafts
The easiest and fastest way to increase power using factory components is to install a long-stroke crankshaft (stroker). In M50B25 (Without vanos), a knee rises from M54B30 with a stroke of 89.6 mm. From the same engine, you need to buy connecting rods, connecting rod bearings, repair pistons, injectors, and main bearings from M50.
We collect (you can leave the firmware, 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 power can be obtained by purchasing Schrick 264/256 camshafts and adjusting the Motronic stock. As a result, we get 220-230 hp. Let's buy a cold air intake, 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, six-throttle intake, BMW S50 injectors, a light flywheel, make cylinder head porting, buy an equal-length exhaust manifold and direct-flow exhaust. After tuning, this M50B30 develops about 270-280 hp.
If this is not enough, you can bore a block for 86.4 mm pistons from S50B32 and get a displacement of 3.2. Buy S52B32 camshafts and get about 260 hp.
The vanos M50B25 can be converted into a 2.8 liter engine by installing a crankshaft with 84 mm travel and connecting rods from M52B28. Together with the SIEMENS MS41 firmware, this will give +/- 220 hp, compression ratio ~ 11. 
VANOS system control
The solenoid valve of the VANOS system is controlled by a controller and depends on the coolant temperature, load and engine speed. At the moment of switching the system for changing the angle of opening of the valves, the settings for the start of injection and ignition are changed. To avoid frequent, repeated switching of the VANOS system, the control is carried out in the hysteresis mode.
M50B25 Turbo
In the case when the atmospheric engine is small or the costs for its implementation are too high, you can organize a turbo version on a 2.5-liter engine. If tuning is supposed to be budgetary, 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 the manifold, assemble all the piping, clamps, boost controller, intercooler, etc. Put everything on the stock piston, after installing a thick Cometic cylinder head gasket, 440 cc injectors, a Bosch 044 fuel pump, an exhaust on a 3 ″ pipe, an EFIS 3.1 brain (or Megasquirt), adjust it and get about 300 hp at 0.6 bar. At 1 bar ~ 400 HP
Something similar can be built by buying a compressor kit M50 and installing it on a piston stock. The compressor output will be noticeably lower than that of the turbine.
Even more power can be obtained by purchasing and installing a turbo kit on the original Garrett GT35, CP Pistons 8.5 compression, Eagle connecting rods, ARP bolts, performance injectors (~ 550 cc). With kits like this, you can increase the power up to 500 ++ HP. Similar projects can be built on a 3-liter stroker.
Functioning of the VANOS system
The VANOS system in the M50 is controlled by the engine-specific digital electronics. The controller switches the 4/2-way valve by means of an electromagnet and thus acts on the hydraulic piston by means of engine oil pressure. The hydraulic piston is held in one of two possible positions by mechanical stops and the oil pressure acting on it (black-and-white switching mode). There is a movable gear inside the hydraulic piston. This gear, by means of helical gearing, converts the translational movement of the piston into a rotation of the camshaft - relative to the drive sprocket. The hydraulic piston with gear is mounted coaxially with the intake camshaft in a die-cast aluminum housing located on the front of the cylinder head. The 4/2-way changeover valve is designed in such a way that if there is pressure in one chamber, there is no pressure in the other (backflow). When current is applied to the valve magnet, the piston moves through the armature against the spring force to the previous position. The helical spring provides reverse movement to the late position. Thus, in the event of a malfunction of the solenoid or a failure of the control signal, the camshaft automatically returns to a late position. With this emergency function, the engine can be started even if the VANOS is defective. If the camshaft is in an early position during starting, the engine will not start.
