BMW M50B25 / M50B25TU engine
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 M50B25 engine reliability, problems and repair
In 1990, the popular in-line six 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, M50B24). The main difference between the M20 and M50 engines lies in the cylinder head; in the new engine, the head was replaced by 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 140 mm connecting rods and pistons with a compression height of 32.55 mm (38.2 mm on the M50B25).
The control system is replaced by Bosch Motronic 3.3.1.
These power units were used onbMW cars with index 25i.
Since 1995, the М50В25 engine began to be replaced by a new improved engine, and in 1996 the production of the М50 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 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.
BMW M50B25 engine problems and malfunctions
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. Troit. 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. The gaskets of the valve cover and sump may leak, and 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.
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 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 М50Б30, 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. If we 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. Once tuned, this M50B30 develops around 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 camshafts and get about 260 hp.
The vanos M50B25 can be converted into a 2.8 liter engine by installing a crankshaft with an 84 mm stroke 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 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.
1950s. There is a rearmament of the air defense forces of the world leaders with the latest air defense systems and the adoption of supersonic fighter aircraft capable of flying up to 20 kilometers into service. So, at once the Soviet strategic bombers Tu-95, M-4/6 become obsolete. Supersonic bombers were urgently needed, capable of overcoming the opposition of the new air defense missile systems and enemy air force fighters.
Experienced design bureau under the leadership of V. Myasishchev, in accordance with the resolution of the Council of Ministers of the USSR of 1954, which provided for the creation of a split long-range bomber, consisting of a strike bomber and a carrier with 4 turbojet engines, begins the development of a supersonic strategic intercontinental bomber called the M-50. It was intended to be a quick replacement for the M-6 (3M) jet bomber.
According to the assignment received, the new strategic bomber was required to:
- develop a maximum speed of at least 1.5 M;
- have a cruising speed of 1500 ± 100 km / h;
- climb to a height of at least 14 kilometers;
- Deliver a bomb load to a range of 13 thousand kilometers.
By 1955, the preliminary design of the "carrier + bomber" was ready. But in mid-1955, the task was changed - now the developers were required to create a standard intercontinental bomber flying at supersonic speed. The new aircraft received 4 turbojet bypass engines NK-6 or VD-9. In 1956, the designers were given the task of installing the M16 - 17 turbojet engines on the aircraft. The designers at this time were busy looking for the best aerodynamics of the aircraft. Four dozen different models were enumerated. As a result, the models created according to the "duck" scheme were recognized as the best. It takes designers about a year to create an aerodynamic structure. The engines were placed as follows - two engines on pylons were suspended under the wing, two engines were installed on the wing end switches.
Due to the fact that a supersonic bomber is a new aircraft that has not yet been created by anyone, they demanded the almost impossible from the designers - to provide a speed of more than 1.5 M and a flight range of more than 10,000 kilometers, and this with a high fuel consumption of turbojet engines.
To begin with, the crew is reduced, the M-50 receives only a navigator and a pilot. They are placed one after another (tandem scheme). The control of the aircraft and equipment is automated as much as possible, thereby ensuring the ability of the reduced crew to fully control the aircraft. Reserve control - hydromechanical. Switching to manual control mode is possible at any part of the flight.
Motor control - fly-by-wire with 3-fold redundancy. To ensure automatic control, a task was given to Soviet developers of radio electronics to accelerate miniaturization of the existing element base (otherwise the advantages of automation were nullified by the weight characteristics of radio electronics). The proposal to use alternating 3-phase current generators is associated with the reduction in weight.
On board the M-50, the equipment of the flight and navigation complex is installed. It included: radio communication station "Planet", fighter radio station ultra-shortwave RSIU-3M and emergency radio station "Kedr-S". In addition, the on-board equipment includes a device for conversations SPU-6, radio altimeters RV-5/25, a request-response station, an irradiation notification station "Sirena-2", etc.
Flight performance increases:
- speed range - 270-2000 km / h;
- flight altitude up to 16 kilometers;
- takeoff maximum weight up to 250 tons (170 of which are fuel);
- the possibility of refueling in the air (two refueling on the route of maximum range).
- the aircraft received an all-moving tail.
To ensure a safe transition to supersonic, a floating center of gravity is provided, which is adjusted by driving the fuel in the desired direction. The on-board automatic control system "ABSU-50" is of classic design. A special analog simulator was created to train pilots to fly a new aircraft.
However, not everything went smoothly with the center of gravity. To reduce instability, the horizontal tail is almost doubled. The installed all-revolving keel helped the designers to reduce its overall area, weight and aerodynamic drag, which contributed to the stability of the aircraft during takeoff / landing, especially in a crosswind. But the airframe design still remained quite heavy and did not fit into the specified parameters. The manufacture of some structural elements was carried out in the USSR for the first time, as an example - one of the elements weighing 4 tons was created from a workpiece weighing more than 40 tons.
To reduce weight, the wing and fuselage pressurized compartments served as fuel tanks. To accelerate takeoff, the front landing gear by turning the wheel bogie lifted the front of the aircraft. To reduce the mileage during landing, brake skis were used. In the design of the aircraft, equipment and units from M-4/6 (3M) jet bombers were widely used. The intercontinental supersonic bomber was created as a strategic means of delivering bombs to enemy territory, but already in 1958 it was proposed to install 45B-type ballistic gliding missiles on it. By the end of the spring of 1956, the designers built a prototype and presented the commission to the customer. For a month of work, the commission came to disappointing conclusions:
- the designers are not able to achieve a given range at cruising speed by an aircraft without refueling;
- the maximum range (two refueling) is provided, but the refueling of the aircraft is carried out at low speeds and altitudes, which is unacceptable (the aircraft may be intercepted or destroyed by the enemy);
- the length of the takeoff roll (3 kilometers) is not maintained without additional accelerators;
- the requirements for self-defense of the aircraft are not fully met;
- Conclusion: the draft design and layout cannot be approved.
The designers, after a series of meetings with specialists from some research institutes, turn to the customer, represented by the Air Force Commander-in-Chief, with a request to revise some of the requirements of the terms of reference:
- mandatory installation of additional boosters on the aircraft;
- the minimum number of weapons for the defense of the aircraft;
- reducing the range without refueling.
By the fall of 1956, the layout of the aircraft was approved, but the engines for installation on board the aircraft were not yet ready. The prototype is equipped with VD-7 turbojet engines. Running engines and systems on the ground began in 1959, after which the M-50A prototype was sent to the OKB base for fine-tuning.
In 1958, the OKB under the leadership of V. Myasishchev was exempted from state tests on the M-50 aircraft. Two aircraft under construction with installed M16 - 17 and VD-7 engines are being transferred for testing a modification of the M-50 aircraft - the improved M-52.
The designers proposed several projects for the development of the M-50 aircraft:
- refueling tanker for refueling super-high-speed aircraft in the air at high speeds and altitudes;
- M-50LL - flying laboratory for research of propulsion systems;
- M-51 - unmanned aircraft carrier of nuclear weapons.
In 1959, prototype testing began. 10/27/1959 M-50A first rises into the sky. Installed turbojet engine VD-7. To achieve the required thrust, the underwing engines received afterburners. The prototype was unable to overcome the speed of 1M (0.99M). In total, the prototype made two dozen sorties, after which, in 1960, work on the M-50 ceased in favor of the M-52, an improved version of the M-50.
In 1961, it was decided to demonstrate the M-50 at the Tushino military parade. The plane took off 4 more times for training purposes, after which it took off for the last time at the parade in Tushino. After the plane was transferred to the Air Force Museum (Monino), where it remains to this day.
Modifications:
- M-50A - prototype. The only one flying of all the aircraft created. Board number 023, after the parade was assigned number 12;
- M-50 - the basic version of a strategic bomber:
- M-52 - an improved version of the M-50. Some of the aircraft were built, but it never took off;
- M-53 - aircraft project. Features - placement of all engines in underwing gondolas;
- M-54 - aircraft project. Features - a wing with a small sweep along the trailing edge;
- M-56 - further development of the M-50. The technical project started in 1959. Features - 6 engines are housed in 2 packages. Fixing the horizontal tail and refusal to pump fuel to level the center of gravity. Estimated maximum speed up to 3.2 M;
- M-55 - civilian version of the M-56. There were sub-variants of the M-55 A / B / V. Differences - the number of installed engines and passenger seats;
- M-70 - modification in favor of the Navy. Features - for takeoff / landing, a hydro-ski was used, an arrow-shaped wing.
The main characteristics of the flying M-50A:
- wing - 27.3 meters;
- length - 58.4 meters;
- height - 8.3 meters;
- empty weight / fuel / max - 78.8 / 66/118 thousand kilograms;
- engines used - two turbojet engines VD-7M and two turbojet engines VD-7B;
- speed - 0.99 M;
- flight range - 3.1 thousand kilometers (without refueling);
- high-rise ceiling - 5 kilometers;
- crew - pilot and navigator;
Sources of information:
http://www.dogswar.ru/oryjeinaia-ekzotika/aviaciia/4439-strategicheskii-bomb.html
http://www.airwar.ru/enc/bomber/m50.html
http://ru.wikipedia.org/wiki/%D0%9C-50
The BMW M50 engine is available in two versions, with a volume of 2.0 and 2.5 liters and was produced at the Steyer plant. Until 1996, a total of 943 795 engines were produced.
The BMW M50 differs from the M20 in many design features, including lower CO2 emissions and fuel consumption, higher efficiency and power, as well as stability and performance.
The main difference compared to the M20 is the 24-valve cylinder head and two overhead camshafts (DOHC), which are driven by two timing chains (the timing belt in the M20), the tappets are low maintenance, the hydraulic compensator, all parts of the ignition system are under plastic valve cover, forged connecting rods (C45), lightweight pistons, high compression ratio, full sequential fuel injection, the intake manifold has completely smooth inner walls and is 50% lighter than the aluminum intake manifold from the M20.
Based on the M50 motor, it was created, which was installed on.
To meet the power targets set for the M50 engine, a completely new DOCH (double overhead camshaft) cylinder head with 4-valve technology has been developed, the feature of which is low gas exchange rate, ideal spark plug position and reduced movable mass of each valve ...
BMW M50B20 engine
This version of the power unit was installed on,
BMW M50B24 engine
2.4-liter version of the BMW M50 engine with a volume of 2.4 liters (2394 cc) which was produced for cars 3 and 5 series of Thai specification. Its maximum power is 188 hp. (138 kW) at 5900 rpm, and the torque is 235 Nm at 4700 rpm. Piston diameter 84 mm and 72 mm stroke.
BMW M50B25 engine
BMW M50 engine characteristics
| M50B20 | M50B25 | ||
| engine's type | inline 6-cylinder | ||
| mounting position | in front | 30º to the outlet side | |
| sideways | 2.28º back | ||
| effective engine displacement | dm³ | 1990 | 2494 |
| piston stroke | mm | 66 | 75 |
| cylinder diameter | mm | 80 | 84 |
| 0,825 | 0,893 | ||
| power | kW / hp | 110/150 | 140/190 |
| at speed | rpm | 5900 | 5900 |
| torque | Nm | 190 | 245 |
| at speed | rpm | 4700 | 4700 |
| specific power | kW / dm³ | 55,3 | 56,1 |
| compression ratio | :1 | 10,5 | 10,0 |
| cylinder working order | 1-5-3-6-2-4 | ||
| maximum piston speed | m / s | 14,3 | 16,25 |
| valve diameter | mm | ||
|
30 | 33 | |
|
27 | 30,5 | |
| valve stroke | mm | ||
|
9,7/8,8 | 9,7/8,8 | |
| flow area | vp / issue | 240º / 228º | 240º / 228º |
| valve opening angle | vp / issue | 96º / 104º | 101º / 101º |
| fuel | high octane unleaded gasoline | ||
BMW M50 engine structure / mechanics
M50 engine: 1 - Oil pump; 2 - Drive belt; 3 - coolant pump; 4 - Thermostat; 5 - Oil filter; 6 - Chains; 7 - Inlet
collector; 8 - Plugs and ignition coils; 9 - Camshafts; 10 - Hydraulic pusher;
Crankcase / crank mechanism
Feature:
- new development - torsionally rigid crankcase, optimized by weight;
- distance between cylinders: 91 mm, cylinder diameter (2.0 liters): 80 mm, cylinder diameter (2.5 liters): 84 mm;
- nodular cast iron crankshaft with 7 main bearings and 12 counterweights;
- cast flywheel;
- torsional vibration damper with integrated incremental gearing;
Cylinder block technical parameters, mm:
M50 engine crankcase block: 1 - Cylinder block with pistons; 2 - Bolt with a hexagon head M10X75; 3 - Oil nozzle; 4 - Plug D \u003d 12.0MM; 5 - Bolt of the bearing cover; 6 - Oil nozzle; 7 - Cover D \u003d 45MM; 8 - Threaded plug; 9 - O-ring; 10 - Centering sleeve D \u003d 13.5MM; 11 - Centering sleeve D \u003d 10.5MM; 12 - Centering sleeve D \u003d 14.5MM; 13 - Seal. asbestos-free block crankcase kit;
Crankshaft with bearing shells of the engine M50: 1 - Revolving crankshaft with bearing shells; 2 and 3 - Thrust bearing shells; 4, 5, 6 and 7 - bearing shell;
Pistons
The M50 engine is equipped with aluminum pistons with thermostatic inserts. There are four valve pockets in the piston crown, two for the intake and exhaust valves.
The piston crown of a 2.5-liter engine additionally has a segmented recess (there is no segment recess in a 2-liter engine). The piston crowns are spray-cooled with oil. The spray arms are located in the crankcase in the area of \u200b\u200bthe crankshaft main bearings.
Motor piston M50: 1 - Piston; 2 - the piston pin; 3 - a spring retaining ring; 4 - Repair kit of piston rings;
Piston of the M50 engine: on the left side is the piston of a 2.0-liter engine, on the right - a 2.5-liter power unit;
Piston rings:
- upper compression ring: cylindrical ring plated with chrome, height 1.5mm
- lower compression ring: tapered ring with a groove on the working surface, 1.75 mm high
- oil scraper ring: so-called slotted box-type with coil spring expander, 3 mm high
Camshaft drive
The drive is carried out by two single-row roller chains:
- Main drive (primary circuit):
- from the crankshaft to the exhaust camshaft with a guide bar on the driven chain
- hydraulically damped tension bar
- Auxiliary drive (secondary circuit):
- from exhaust to intake camshaft
- guide bar and hydraulically damped tensioner
Both chains are sprayed with oil where they leave the sprockets. The primary drive chain is supplied with a sprinkler located above the first main crankshaft bearing. The secondary drive chain is supplied with a spray gun in the upper chain tensioner housing.
The valves are driven by two semi-bearing overhead, cast hollow camshafts.
Camshafts and poppet followers are assembled with bearing housing to facilitate maintenance.
The head of the cylinder block of the M50 engine: 1 - the head of the cylinder block with support bars; 2 - Support bar, outlet side; 3 - Centering sleeve D \u003d 9.5MM; 4 - Hex nut with washer; 5 - Valve guide sleeve; 6 - the inlet valve seat ring; 7 - Exhaust valve seat ring; 8 - Centering sleeve D \u003d 9.5MM; 9 - Dowel pin M7X95; 10 - Dowel pin M7 / 6X29.5; 11 - Dowel pin M7X42; 12 - Dowel pin M7X55; 13 - Dowel pin M6X30-ZN; 14 - Dowel pin M6X45; 15 - Dowel pin M6X35-ZN; 16 - Centering sleeve D \u003d 8,5X9MM; 17 - Dowel pin M8X50; 18 - Centering sleeve D \u003d 10.5MM; 19 - Cover D \u003d 28MM; 20 - Screw plug M24X1.5; 21 - Screw plug M18X1.5; 22 - Screw plug M8X1; 23 - Screw plug M12X1.5; 24 - O-ring; 25 - Cover 22.0MM;
Valve seat characteristics
| Parameter |  Valve seat |
|||
| inlet | graduation | inlet | graduation | |
| M50V20 | M50V25 | |||
| The diameter of the bore of the seats in the block head, mm: | ||||
|
34 | 28 | 34 | 31,5 |
|
34,2 | 28,2 | 34,2 | 31,7 |
|
34,4 | 28,4 | 34,4 | 31,9 |
| with tolerance, mm | 0.00 to +0.025 | 0.00 to +0.025 | ||
| Working chamfer angle, degrees | 45 | 45 | 45 | 45 |
| External correction angle | 15 | 15 | 15 | 15 |
| Internal correction angle | 60 | 60 | 60 | 60 |
| Working chamfer width, mm | 1,40-1,90 | 1,40-1,90 | ||
| Outside diameter, mm | ||||
|
34,1 | 28,1 | 31.6 (nominal 34.1) | |
|
34,3 | 28,3 | 31.8 (1st repair 34.3) | |
|
34,5 | 28,5 | 32.0 (2nd repair 34.5) | |
| with tolerance, mm | 0.00 to -0.025 | 0.00 to -0.025 | ||
| Saddle height, mm | ||||
|
7,3 | 7,3 | ||
|
7,5 | 7,5 | ||
|
7,7 | 7,7 | ||
| with tolerance, mm | 0.00 to -0.01 | 0.00 to -0.01 | ||
M50 engine valves
| Parameters | Inlet valves | Exhaust valves | ||
| M50B20 | M50B25 | M50B20 | M50B25 | |
| Head diameter, mm | 30,00 | 33,00 | 27,00 | 30,50 |
| Head diameter tolerance, mm | 0.0 to -0.016 | 0.0 to -0.016 | ||
| Rod diameter, mm | ||||
|
6,975 | 6,975 | ||
|
7,10 | 7,10 | ||
|
7,20 | 7,20 | ||
|
0.00 to -0.015 | 0.0 to -0.015 | ||
| Clearance between guides and valve stems | 0,5 | 0,5 | ||
| Guide bush parameters, mm | |
| total length | 43,5 |
| Outside diameter: | |
|
12,5 |
|
12,6 |
|
12,7 |
| Manufacturing tolerance | +0.033 to +0.044 |
| Inner diameter: | |
|
7,0 |
|
7,1 |
|
7,2 |
| Manufacturing tolerance | 0.0 to +0.015 |
| Diameter of holes for guide bushings: | |
|
12,5 |
|
12,6 |
|
12,7 |
| Manufacturing tolerance | 0.00 to -0.018 |
Cylinder head
The cylinder head of the M50 engine with diametrically opposed inlet and outlet channels with
- four valves per cylinder
- two camshafts
- disc pushers with hydraulic clearance adjustment (HVA)
The very small valve angles flatten the combustion chamber and concentrate the fuel mixture around the centrally located spark plug.
Sectional view of BMW M50 cylinder head
Hydraulic clearance and valve drive control
(HVA) integrated in the poppet follower. This reduces noise generation and makes maintenance easier:
- No need to install and check valve drive clearance
- The valve timing is clearly observed for a long time
The hydraulic pusher is mainly composed of two moving parts, the pusher and the cylinder.
The force of the spring moves both parts apart until there is no gap between the camshaft and the valve stem.
The check valve serves to fill and close the high pressure chamber.
Oil circulation
The oil is supplied via a duocentric pump with an internal rotor and an integrated oil pressure regulation system (similar to c).
The pump is located in the oil pan and bolted to the cylinder block. It is driven by a single-row roller chain directly from the crankshaft.
The oil filter is installed vertically on the intake side. The paper filter cartridge can be replaced from the top. To replace the filter, unscrew the central fixing bolt of the oil filter cover.
Sectional M50 Engine - Front View
Cooling system
The water pump is integrated in the chain case. The mechanical seal ring has a ceramic surface, the impeller is made of plastic, the body is made of aluminum.
The hot water is drawn off for heating from the cylinder head.
The crankcase and cylinder head are cooled primarily in the longitudinal direction. The main stream of water flows from front to back, rises through the connecting channels to the cylinder head and flows from back to front there.
Auxiliary units
The auxiliary units are driven by a maintenance-free V-belt.
The power steering pump and generator are located on the left in the direction of travel, the air conditioning compressor (SA) is on the right, close to the engine and mounted rigidly, not elastic.
Auxiliary units are driven on two levels:
- Level 1 (main drive):
- crankshaft - water pump (fan) - generator - power steering pump or tandem pump, respectively (level control)
- Level 2 (additional drive):
- crankshaft - air conditioning compressor
An external spring booster, a belt tensioner located on the driven belt strand, is hydraulically damped in one direction. The tensioner roller is made of plastic.
Spark plug
A separate plastic deflection roller near the generator increases its wrap angle. In the ignition system of the M50 (RZV) engine, a spark plug is also used - an "F" spark plug with an SAE contact and a three-pointed side electrode.
The side electrode was developed by BMW in cooperation with suppliers especially for 4-valve engines. The combustion in these engines is tougher and faster and places higher demands on the spark plug.
The side electrode is welded to the candle body at three points (on 3 legs) and has the shape of a triangle relative to the central electrode.
The gap between the electrodes on a new plug is 0.9 mm +/- 0.1 mm. The candle has resistance< 1 кОм.
Ignition coil
Each spark plug has its own ignition coil. The coil is screwed onto the iron bag thus providing electrical contact with the ground.
The high voltage is supplied to the spark plug by means of a silicone funnel, a contact rod with an interference suppression resistor and a cone-shaped contact spring that presses against the SAE contact of the plug. This design provides the highest secondary voltage to the ignition system, since there are no high voltage wires and losses associated with voltage distribution.
Engine ignition coil M50: 1 and 2 - Ignition coil; 3 - the tip of the wire to the spark plug; 4 - Hex nut; 5 - Shield; 6 - Hexagon head bolt; 7 - Connector plug housing; 8 - Spark plug;
The ignition coil is galvanically isolated, i.e. the end of the secondary winding is pulled out of the coil. It is designated "4A" and is the middle contact of the three-pole plug connection:
- on the primary side of terminals 1 and 15
- contact "4A"
Its contact tongue is longer. Thus, for safety reasons, when the plug is disconnected, this contact is disconnected last.
BMW M50TU engine
From September 1992 (PU92), the BMW M50 engine installed up to this point in the BMW E36 and E34 is being replaced by a revised version M50 TU (TU - Technically Reworked).
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 medium speed range
- reduced fuel consumption
- improved idling performance while reducing idle speed
- improved exhaust characteristics (reduced emission toxicity)
- improved throttle response
- best engine acoustics
Improvements to the M50TU (M50TU) engine 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 a 2.5-liter engine ( M50TUB25)
- application of the Siemens MS 40.1 engine controller in all E36 and E34 models with an engine M50TUB20
- increasing the compression ratio
- using the VANOS system
- changes in the crank mechanism (new pistons and connecting rods)
- a new idle speed control in the 2.5-liter M50TUB25 (ZWD-5) engine
- using a thermofilm air flow meter
- by reducing the diameter of the valve stem and using one valve spring
- the use of disc pushers and spring plates, optimized for weight
- changes in valve acceleration characteristics
- by changing the crankshaft vibration damper
BMW M50 TU engine characteristics
| technical specifications | M50TUB20 | M50TUB25 | |
| engine's type | inline 6-cylinder | ||
| mounting position | in front | 30º to the outlet side | |
| sideways | 2.28º back | ||
| effective engine displacement | dm³ | 1990 | 2494 |
| piston stroke | mm | 66 | 75 |
| cylinder diameter | mm | 80 | 84 |
| piston stroke / bore ratio | 0,825 | 0,893 | |
| power | kW / hp | 110/150 | 140/190 |
| at speed | rpm | 5900 | 5900 |
| torque | Nm | 190 | 245 |
| at speed | rpm | 4200 | 4200 |
| specific power | kW / dm³ | 55,3 | 56,1 |
| compression ratio | :1 | 11,0 | 10,5 |
| cylinder working order | 1-5-3-6-2-4 | ||
| maximum piston speed | m / s | 14,3 | 16,25 |
| valve diameter | mm | ||
|
30 | 33 | |
|
27 | 30,5 | |
| valve stroke | mm | ||
|
9,0/9,0 | 9,0/9,0 | |
| flow area | vp / issue | 228º / 228º | 228º / 228º |
| valve opening angle | vp / issue | 105-80º (VANOS / 105º) | 110-85º (VANOS / 101º) |
| fuel | high octane unleaded gasoline (Super) | ||
The M50TUB25 was used on the E36 325i / 325is and E34 525i / 525ix.
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.
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:
- more power and improved torque in certain speed ranges
- reduced content of NOX and CH content of exhaust gases in partial load range
- insignificant residual gas content at idle speed; due to this, on the one hand, an improved idle speed due to a more favorable mixture, and on the other hand, lower fuel consumption due to a decrease in idle speed. Improved idle acoustics
- better engine response
- high functional safety
- extensive self-diagnosis and trouble-free troubleshooting
The VANOS shifting 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 chosen:
- M50TU20
- 105º (late switching)
- 80º (early switch)
- M50TU25
- 110º (late switching)
- 85º (early switch)
This results in a maximum switching angle of the variable intake camshaft opening angle of 25º KW (crankshaft angle) for both engine variants.
Components:
- front helical intake camshaft;
- chain sprocket with an internal helical rim;
- hydraulically-mechanically camshaft adjustment device with one hydraulic piston and 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;
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 when 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.
VANOS system control
The VANOS system solenoid valve 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 hysteresis mode.
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 operating 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 functional check the MS40.1 should also read the data from the fault memory.
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 M50 engine problems
The M50 engine is considered one of the most. Possible engine malfunctions are listed below, but it is worth considering the correct maintenance of the motor, because with proper operation, the power unit will show itself in a completely different way:
- overheating: advice - check the condition of the radiator, pump, thermostat, the presence of air locks in the cooling system and the radiator cap;
- troit: recheck ignition coils, spark plugs and injectors;
- rpm float: possible causes of a malfunction - failure of the idle valve or throttle position sensor;
- antifreeze leakage - the expansion tank is cracked;
- failure of individual ignition coils;
- burnout of power keys of ignition control;
- oil flow along the junction of the oil filter cup, valve cover gasket, pan and front cover;
- the fuel supply is turned off;
The power unit of the BMW M50 has been replaced with a.
Diesels 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 atomization. Available in right and left rotation models. A diesel engine of right rotation differs from a diesel engine of a left rotation in the appearance of the reversing clutch, supercharger, seawater pump, exhaust system, “as well as in the location of the fresh water pump and oil injection pump with a centrifuge. The arrangement of the units on diesel engines of left and right rotation is mirror-like.
Diesel M-50 F-3 is designed to operate on high-speed hydrofoils. The rocket-type motor ship has one engine, the meteor-type - two and the "satellite" -type - four engines. The diesel is equipped with reversible clutches, consisting of friction and gear clutches and providing rotation transfer from the diesel crankshaft to the propeller shaft (forward motion), dissociation of these shafts (idling) and changing the direction of rotation of the propeller shaft (reverse).
The forward operating power may vary depending on the purpose within the range of 368-736 kW with a corresponding change in the number of shaft revolutions within 1200 - 1640 rpm, the maximum reverse power is 184 kW at 750 rpm and the operating time is not more than 1 hour ...
The diesel crankcase is cast from an aluminum alloy and consists of two parts. In the upper bearing part there are seven main bearing seats with liners in which the crankshaft rotates. The split steel liners are cast in lead bronze and bored along the shaft journals. The working surface of the liners is coated with a lead-tin alloy. The platforms of the upper part of the crankcase located at an angle of 60 ° serve for the installation of two six-cylinder blocks.
The crankshaft is made of nitrided alloy steel. It has six knees located
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 shock absorber is attached to the rear flange of the crankshaft, which reduces the unevenness of torque under variable loads. Six main and six trailed connecting rods are mounted on the diesel crankshaft.
The I-section connecting rods are made of alloy steel.
The upper heads of the main and trailed connecting rods are the same and have tin bronze bushings pressed into them. The lower head of the main connecting rod is split: the cover is attached to the main connecting rod by means of a wedge with two tapered pins. In the lower head of the main connecting rod, a steel liner filled with lead bronze, consisting of two halves, is installed. The trailed connecting rod is connected to the main connecting rod by means of a pin pressed into the eye of the main connecting rod.
The piston is a stamped aluminum alloy. The piston crown is shaped like a Gesselmann 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 four recesses of the piston crown. The piston pin is made of alloy steel, hollow, with a hardened outer surface, pressed into the piston bosses.
Cylinder blocks - six-cylinder, are installed on the upper crankcase of the diesel engine and are attached to it with anchor pins. Each cylinder block consists of a jacket, six cylinder liners and a head. In the upper part, the sleeve has a collar, with which it rests on the surface of the groove in the block jacket. The lower belt of the cylinder bushing is sealed by five rubber rings: four serve to seal the water cavity, and the fifth (lower) prevents oil from leaking out of the upper crankcase cavity.
Figure: 1. Diesel M-50F-3
Diesel engines of the M-400 type have two six-cylinder monoblocks (the head is molded together with the cylinder block). In monoblocks, six cylinder liners are pressed in, each of which is a connection of two pipes: an inner one made of alloy steel and an outer one 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 at the front of the diesel engine. Each cylinder has four valves - two inlet and two outlet. The valve is pressed against the seat by three coil springs. Each head of the block has two camshafts, the cams of which directly act on the valve discs, which are interconnected by cylindrical gears.
The order of operation of cylinders on a diesel engine of right rotation: 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, at a pressure of 2-4 bar, it is fed through two parallel-connected fuel filters to the high-pressure fuel pump and to the injectors.
The fuel pump is a twelve-plunger pump with two-way cut-off and with separate suction and cut-off. The plunger diameter is 13 mm, the plunger stroke is 12 mm. Fuel supply pressure 700-1000 bar. The order of operation of the pump plungers, counting from the drive end of the roller, is as follows: 2-11-10-3-6-7-12-1-4-9-8-5.
Diesel regulator - all-mode, indirect action, with an elastically connected cataract. Provides speed stability in the range from 500 to 1850 rpm.
The nozzle is of a closed type, with a hydraulically controlled needle. The injector nozzle has eight spray holes with a diameter of 0.35 mm, located so that when the fuel is sprayed, a cone with an apex angle of 140 ° is formed. The fuel injection pressure of 200 bar ensures that the smallest particles are atomized evenly throughout the compressed air volume in the combustion chamber.
Its predecessor was the sensational E28. Even today, this is a really noteworthy car that is very popular. It is safe to say that this is a kind of masterpiece. Let's take a look at the technical characteristics of this model, find strengths and weaknesses.
Salon and equipment
Today, not every car is as comfortable as the E34. The fact is that the center console here is made in such a way that the driver can not only quickly, but also comfortably access all the necessary controls. As for the sensors, they are also installed in the "torpedo" very successfully. While driving, they are clearly visible. In the dark, you do not need to look closely, since the illumination of the devices is at a level. To exclude freezing and fogging of the windows, air ducts are provided, which are not only on the front panel, but also on the doors, which together gives a good result. By the 90s, vehicles were equipped with air conditioning and an airbag for the driver. In addition, it was possible to order a complete set with a cassette recorder, there were no disks at that time. In the maximum configuration, an electric sunroof and a leather interior were installed.
Installed engines on E34
Until the car was discontinued, 13 engines were proposed, 11 of which are gasoline. As for the power, the spread is quite large. The minimum is 115 horses for a gasoline engine and the same for a diesel one. It was also possible to purchase a car with a 340-horsepower engine, but it was exclusive. At the very beginning, it was planned to install the M20 and M30 series with a volume of 2.0 / 2.5 and 3.0 / 3.5 liters. All these motors can be considered native, they have a belt drive, as well as two valves for each cylinder. The lack of hydraulic lifters led to the fact that periodically it was necessary to adjust the thermal clearances, but this was not a problem, since this kind of adjustment had to be performed every 35,000-40,000 kilometers. The belt had to be changed even less often, every 50,000-60,000 kilometers. It is difficult to say what serious flaws the M20 and M30 had, since the assembly was really high quality.
BMW E34 engines: M50 and M60
By 1990, Munich decided to install modified versions of the motors. In almost all respects, they outperformed their predecessors. One of the significant advantages was the presence of the Vanos gas distribution system. The M50 had a displacement of 2.0 and 2.5 liters with a capacity of 150 and 192 horsepower, respectively. The main task of the designers was to increase power, torque and improve efficiency. To achieve all this, 4 valves were installed for each cylinder, various modifications accelerated their filling. The resource of the motors was also at the level. If all operating requirements were met, the engine could travel about 600,000 kilometers. The main drawback is the high sensitivity to overheating, which is why the owners had to constantly monitor the condition of the pump, thermostat and pipes. It is recommended not to wait for the complete failure of any particular BMW E34 spare part, but to replace it before an emergency condition occurs.
Car modifications
An all-wheel drive model was released in 1991. The new modification of the "five" was produced with one 2.5-liter gasoline engine. The priority of torque was given to the rear wheels, as they accounted for about 64%, the remaining 36% on the front. Almost all cars had a five-speed manual gearbox, where an automatic 5-speed gearbox was less common. As for the service life, for example, silent blocks, they are recommended to be changed every 55-60 thousand kilometers. change every 40 thousand kilometers. It is impossible not to mention the power steering, which drivers immediately fell in love with. The steering wheel could become heavier or lighter depending on the speed of the vehicle. This, of course, did not solve the problems with the worm pair, which quickly broke down, nevertheless, on the road, the driver had a feeling of safety and comfort. In principle, even in 2014, it is safe to say that the E34 is a difficult car, but the level of reliability is at its best. If you go through MOT on time, change consumables and take care of the vehicle, then there will be no problems with it.
Technical data with manual transmission
The vehicle is powered by a 2.5-liter engine that produces 192 horsepower. In about 8.5 seconds, the car can accelerate to 100 kilometers, and the maximum speed is 230 km / h. When it comes to fuel consumption, the car is not that gluttonous when you look at its power. On average, this is 9 liters per 100 km. The trunk is also quite roomy, its volume is 460 liters. I must also say that the fuel tank, which can be filled with 80 liters of fuel, will also please. The ground clearance is 120 millimeters. Popular today and which includes the installation of a sports crankshaft and more. All this allows you to get a high-speed car, but at the same time it is very economical. As for the cost, it depends on the condition of the body, as well as under the hood. Most often, there are options from 4 to 9 thousand dollars.
Conclusion
So we did a short overview of the E34. If you are faced with a choice, then do not rush to make a decision. Do not pay attention to the volume of the engine, it is better to look at how the interior has been preserved and in what condition the components and assemblies of the vehicle. First, evaluate the appearance of the BMW E34. In this case, it is advisable not to believe the photographs, but to view them yourself, preferably with a specialist. So you can get an objective assessment, ride and draw conclusions for yourself. That, in principle, is all that can be said about the legendary E34. Expensive repairs more than pay off with the durability and reliability of the vehicle, so you don't have to worry. You need to fill only high-quality oil and gasoline, since any engine, be it M2 or M5, requires careful attitude and good care.
