Absolutely everyone has heard of such a brand as BMW. A rather capacious history of this company deserves respect from motorists. The corporation has been and remains a leader in the automotive industry. The quality and level of development of its products are measured by many machine manufacturers.

Features of the German-made M20 engine

In the first half of the 20th century, the company's engineers were actively engaged in fine-tuning in-line units. One of the successful designs was the 6-cylinder M20 engine from BMW, which became the starting point for subsequent units.

"Twenty" has taken root well in the model ranges of the third and fifth series, as evidenced by the presence of this unit in:

• E12 (1972 - 1981);
• E21 (1977 - 1983);
• E28 (1982 - 1987);
• E34 (1987 - 1990).

Stable operation is provided by 12 valves receiving commands from a rotating camshaft. The layout of the cylinder head is organized according to the SOHC type. The power plant was produced in 4 types:

• M20B20;
• M20B23;
• M20B25;
• M20B27.

The number after the letter B indicates the volume of the product. Owners of old "triples" talk about frequently occurring malfunctions of this kind:

• the formation of a crack in the cylinder head (often between 4 and 5 cylinders) connecting the cooling and crankcase cavities;
• valve damage when the timing belt breaks;
• violation of the position of the tension roller, which causes severe wear of the timing gear.

Reliability above all: the M50 engine from the German concern BMW

The employees of the company did not stop there. The desire to increase dynamics and at the same time not change the overall configuration of the unit resulted in the creation of a new generation engine marked M50.

Key Features:

• four valves per cylinder;
• two camshafts (this made it possible to somewhat disconnect the connection between the intake and exhaust);
• timing chain drive.

This power plant replaced the M20 on the conveyor of the plant, the performance of which at the beginning of the 90s was far from ideal. Two years later, the "fifty" was equipped with a proprietary know-how - an active variable valve timing system VANOS.

At the command emanating from the ECU, with the help of a fluid coupling, the intake camshaft was rotated to a certain angle. As a result of the modernization, the operation of the motor has become effective throughout the entire range of rotation of the crankshaft.

The innovative in-line six-cylinder M50 engine had the following modifications:

• M50B20;
• M50B20TU VANOS;
• M50B25;
• M50B25TU VANOS.

The reliability and durability of this series has been repeatedly noted by many fans of the Bavarian car industry. Malfunctions often occur as a result of unskilled repairs. With high mileage, there were burnouts of the intake valves. Prolonged overheating leads to cracks in the cylinder head.

In pursuit of efficiency: M54 engine under the BMW brand

The corporation decided to celebrate the beginning of the 21st century with a new six-cylinder in-line engine. The motor received such innovations:

• cylinder block cast from aluminum alloy with cast iron inserts;
• Double VANOS system (a breakthrough in the filling compared to the M52);
• optimized oil ring design.

When creating this product, engineers stepped even further, forcing both camshafts to obey the computer. As a result, better throttle response and excellent traction at any speed.

The reliability of BMW M54 engines in E36, E39, E46 bodies has suffered somewhat. Owners note the following problems:

• failure of camshaft position sensors;
• tendency to coking due to the small thickness of the piston rings;
• unstable operation of a cold engine (misfire);
• blown exhaust valves.

M40 four-cylinder engine and BMW's desire for economy

To replace the obsolete M10 in the late 80s, a new line-up for four rubbing pairs (cylinder-piston) came. From the category of new technologies, the M40 got hydraulic lifters and an aluminum cylinder head housing. The chain drive was also replaced with a belt drive. This made it possible to reduce the tone of the power unit.

The series included two modifications:

• M40B16;
• M40B18.

The fuel supply process began to obey electronics thanks to the Bosch M1.3 injection power system. The operational features of the unit are as follows:

• increased sensitivity to the condition of the belts (they are quite thin here);
• rapid wear of a pair of rocker cams due to the instability of the camshaft lubrication process;
• capricious nozzles provoke the occurrence of failures when the car is moving;
• instability of idling (there is a high probability of suction and jamming of the throttle).

The history of the development of the potential of BMW vehicles reflects the constant progress in dynamics and power. Painstaking attention to detail and a high level of ingenuity of the staff contributed to the creation of innovative in-line engines discussed above.

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Engine BMW М20B20 2.0i 206KA

The M20 engines were first introduced to the general public in 1977 and were, in fact, a modification of the M30 power units, which has a much smaller displacement. They were created primarily in order to provide the very first car of the fifth series (E12) with an inexpensive, economical and modern engine. They were also used to equip machines of the third series, since there was simply not enough space for them for the M30. M20 is an in-line power unit with 6 cylinders and 12 valves in its design, as well as a timing belt drive. Its cylinder block is made of cast iron, but is equipped with an aluminum head. Interestingly, until 1982, this engine was produced under the M60 marking, which in 1983 was assigned to a completely different motor of the Bavarian company. The cost is 35,000 rubles.

Engine Specifications M20B20 (206KA)

Engine model: M20B20 (206KA)

Volume: 1990 cm3

Power: 129 HP

Number of cylinders: 6

In total, there are four modifications of the M20 power unit: M20V20, M20V23, M20V25, M20V27. Between themselves, they differ in volume (from 2.0 to 2.7 liters), power and some design features. A distinctive feature of these engines is the absence of a fuel pump in the cylinder block, as well as the use of various types of gas distribution mechanisms. In addition, there are modifications of the M20 power units with different intake valves (both in size and geometric configuration). It should also be taken into account that the M20V27 engine was heavily derated by the designers, although it has a high torque.

At our disassembly you can buy such

BMW M20B20 engine

Characteristics of the M20V20 engine

Production	Munich Plant
Engine brand	M20
Release years	1977-1992
Block material	cast iron
Supply system	carburetor/injector
Type	in-line
Number of cylinders	6
Valves per cylinder	2
Piston stroke, mm	66
Cylinder diameter, mm	80
Compression ratio	9.2 9.8 9.9 9.8 8.8 (see modifications)
Engine volume, cc	1991
Engine power, hp / rpm	122/6000 125/5800 126/5800 129/6000 129/6000 (see modifications)
Torque, Nm/rpm	160/4000 170/4000 170/4000 174/4000 174/4300 (see modifications)
Fuel	92-95
Environmental regulations	-
Engine weight, kg	~113 (dry)
Fuel consumption, l/100 km (for E30 320i) - city - track - mixed.	13.0 7.5 9.5
Oil consumption, g/1000 km	up to 1000
Engine oil	5W-30 5W-40 10W-30 10W-40 10W-50 15W-50
How much oil is in the engine, l	4.25
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	- ~250-300
Tuning, HP - potential - no loss of resource	400+ n.a.
The engine was installed

Reliability, problems and repair of the BMW M20B20 engine

The inline six-cylinder BMW M20B20 engine ("Spider") appeared in 1977 as a replacement for inline fours and is the ancestor of the M20 family, which also includes the 2.3-liter M20B23, 2.5-liter and M20B27 working volume of 2.7 liters. The M20B20 motor was used on cars with the 20i index.
The engine is based on a cast-iron cylinder block, on top is an aluminum 12-valve cylinder head with a single SOHC 12V camshaft. At first, a head known as 200 was used, later it was replaced by 731, which was distinguished by a large diameter inlet ports. The diameter of the intake valves is 40 mm, exhaust 34 mm. There are no hydraulic lifters, valve adjustment is required every 10-20 thousand km, valve clearances inlet 0.25 mm, outlet 0.3 mm. The timing drive uses a belt, the replacement of which is required every 50 thousand km, when the belt breaks, the engine bends the valve.
The power supply system on the first variations of the engine is carburetor; since 1981, carburetors have given way to mechanical and electronic injection.
In 1990, the 2-liter representative of the M20 series was replaced by a new engine -.

BMW M20B20 engine modifications

1. M20B20 (1977 - 1981 onwards) - the first version of the engine with a carburetor fuel supply system. Compression ratio 9.2, power 120 hp at 6000 rpm, torque 160 Nm at 4000 rpm.
2. M20B20 (1981 - 1987) - version with L-Jetronic electronic multi-point injection, compression ratio 9.8, power 125 hp at 5800 rpm, torque 170 Nm at 4000 rpm.
3. M20B20 (1982 - 1984) - modification with mechanical multi-point injection K-Jetronic, compression ratio 9.9, power 126 hp at 5800 rpm, torque 170 Nm at 4000 rpm.
4. M20B20 (1985 - 1991) - engine with LE-Jetronic electronic direct injection, compression ratio 9.8, power 129 hp at 6000 rpm, torque 174 Nm at 4000 rpm.
5. M20B20 (1987 - 1992) - version with Motronic electronic direct injection, compression ratio 8.8, power 129 hp at 5800 rpm, torque 174 Nm at 4300 rpm.

Problems and disadvantages of BMW M20B20 engines

The cons and malfunctions of the M20B20 engine are completely similar to the older 2.5-liter counterpart M20B25, you can find out about them. Among other things, if we are talking about the BMW five, this power unit is also too weak, so for the E34 it is better to buy the M50B25 engine.

BMW M20B20 engine tuning

M20B20 Stroker

Over the long years of the existence of the M20 series, many options have been developed to increase the working volume of the M20B20. The simplest and most effective option is a stroker up to 2.3 L, since the height of the cylinder block of both engines is the same. To convert M20B20 to M20B23, it is enough to buy a crankshaft, pistons, connecting rods and flywheel from M20B23, a new cylinder head gasket, bolts, liners and rings. By building such an engine, you will get approximately 150 hp.
An interesting option is to convert the M20B20 to M20B25, but we will go further and increase the displacement from 2.0 L to 2.8 L. For these purposes, we need to bore the cylinders to 84 mm, buy an M52B28 crankshaft, leave the connecting rods stock, M20B25 Kat pistons (cut by 3 mm ), flywheel M20B20 Carb. Plus, replace the radiator, the standard one will not cope. As a result, we get a more powerful M20B28.
Then everything is like : shafts, porting, inlet, outlet ...
You need to understand that when boring cylinders up to 84 mm, the block walls will become very thin and the engine life will be significantly reduced. Similar motors drive about 10,000-20,000 km.

M20B20 Turbo

The construction of the M20 turbo on the weakest engine of the series is a dubious decision, but it has the right to life. To implement the project, you need to buy a turbo kit based on a Garrett T04E or Garrett GT30 turbine, with a turbo manifold, blow-off, intercooler, piping, oil supply and oil drain, oil cooler, boost controller, wastegate, downpipe and a full 2.5” exhaust. In addition, it is necessary to replace the pistons and connecting rods with forged ones, the compression ratio is ~ 8.5, and also buy a metal cylinder head gasket. Added to this are 440 cc injectors, Walbro 255 lph fuel pump, boost pressure sensor, oxygen sensor, oil pressure sensor, exhaust gas temperature sensor, Megasquirt ECU.
When building such a turbo project on the M20B28 Stroker, the engine power will be about 350-400 hp.

!!

The BMW M20 engine is a 6-cylinder engine with 12 valves, small (as for BMW cars) and having a camshaft belt drive. The unit was developed in 1977 and entered the conveyor with the M60 marking.

The engine was mainly intended for the new and first car of the 5 series in the back of the E12, which appeared in the same year. It was intended to create economical, cheap and modern versions of cars. In addition, a more powerful engine was also needed for the BMW 3 series, but there was extremely little space under the hood of these cars for (M89).

Specifications BMW M20

Compared to its older brother M30, this unit had a lighter design and a camshaft belt drive. But, despite this, it remained with a cast iron cylinder block and an aluminum head. An important innovation in the M60 was the appearance of a camshaft belt drive instead of a chain.

In 1982, it was slightly modernized and received the M20 marking. Also, previous releases began to be called the M20, and the name M60 in 1993 was assigned to a completely different model. There were minor differences between the M20 and M60: the M20 did not have a gas pump in the cylinder block, and the number of teeth on the timing belt also changed, the M60 had 111 teeth, and the M20 had 128 teeth, and since 1985 - 127. Thus, they changed belt tensioner pulley and timing gear.
Further improvement of the M20 gave a version of 2.5 liters and 170 horsepower, as well as its high-torque derated version with a volume of 2.7 liters.

A feature of the M20 B27 engine with a 2.7 liter volume was that the unit was very heavily deformed. It showed only 125 horses at 4800 rpm, but nevertheless it had a fairly large torque of 241 Nm at 3200 rpm. For this, he was awarded the nickname "gasoline diesel". Cars with such engines were marked 325e and 525e, and in America - 328e and 528e.

It was put on cars 3rd and 5th series.

Vehicles with BMW M20 engine

Third series:

• E21, model 320 with a 2-liter unit, carbureted, models 323 and 323i with a 2.3-liter engine, carburetor or K-Jetronic mechanical injection.

• E30, models 320i and 323i, engines with a volume of 2 and 2.3 liters, had a K-Jetronic or similar L (E) -Jetronic injection system, models 325i and 325e with engines of 2.5 and 2.7 liters and having Motronic 1.0 injection system.

Fifth series:

• E12, model 520 with a volume of 2 liters, carburetor only.

• E28, 520i model equipped with K or L(E)-Jetronic system, 525e with 2.7 liter engine and Motronic 1.0 system.

• E34, 520i and 525i models with 2.5 liter engine and Motronic 1.0.

BMW M20 firmly occupied its niche in the engine market, located exactly between the M10 and M30. He also lived a very long production life and became widespread, including in Russia, where he was actively sold out in a complete set with a body number 34.

Historical reference

This engine first came off the assembly line in 1977 and was produced until 1993.
It was intended primarily for the new and first BMW 5 Series - E12, which left the stocks in the same 1977.

It was the M20 that subsequently served as the basis for the development of such engines as the M21, M70 and V12.

Specifications

The M20 is a six-cylinder, twelve-valve engine that is fairly small by BMW standards. Relative to its predecessor, the M30, the motor has a lighter design and a camshaft belt drive. However, the M20 retained its cast iron cylinder block and aluminum head.
The volume of the engine upon completion of all improvements was 2.5 liters, and the power was 170 hp.
Weight M20 - 113 kg.

M20 Modifications on BMW 5 Series Models

M20B20

M20B25

M20V27

The most common faults

When operating the M20 engine, the following problems often occur:

• the formation of a crack in the cylinder head connecting the cooling and crankcase cavities;
• valve damage when the timing belt breaks;
• violation of the position of the tension roller, which leads to severe wear of the transmission of the gas distribution mechanism.