BMW M20B20 engine

The engine began production in 1977. The cylinder block is made of cast iron. The power supply system depends on the type of motor, there are both carburetor and injector. The engine has an in-line structure, 6 cylinders with 2 valves each. The stroke of the piston is 66 millimeters. The diameter of the cylinders is 80 millimeters. The compression ratio depends on the modification of the motor, varies from 9.2 to 8.8. The exact volume of the motor is 1991 cubic centimeters. Maximum power also depends on the modification, varies from 122 to 129 horsepower. Torque is no more than 174 at 4.3 thousand rpm. It is recommended to refuel with 95 gasoline. The total weight of the engine is 115 kilograms. In the city consumes about 13 liters per 100 kilometers, on the highway 9.5, in mixed mode spends 9.5 liters. Oil consumption is up to a liter per 1 thousand kilometers. It is recommended to use 5W-30 or 5W-40. The engine contains 4.25 liters of oil. It is required to change every 7 thousand kilometers. The motor operates at a temperature of 90 degrees Celsius. The engine resource is more than 250 thousand kilometers.

M20B20 engine specifications

Advantages

The M20B20 is popularly known as the “Spider”. It began to be used as a counterpart to the inline four-cylinder motor. Became the basis of the entire wide family of M20. On top of the cylinder block, the cylinder head for 12 valves, has only one camshaft. Initially used head 200, later began to use 731, characterized by a larger diameter for the channels. There are no hydrocompensators, valves require adjustment every 15 thousand kilometers. The timing is presented in the form of a belt, which must be changed every 50 thousand kilometers. If the breakage is allowed, the valves will be bent. The first modifications of the motor were equipped with a carburetor. In 81 began to use mechanical and electronic injection.

Disadvantages

The following disadvantages of the M20B20 are highlighted.

1. The engine overheats quickly, due to a malfunction of the standard cooling system. It is necessary to make sure that there are no air plugs, get rid of dirt on the radiator.
2. The camshaft pastels become defective after 200,000 kilometers. A new cylinder head will need to be purchased.
3. Overheating causes cracking of the cylinder head, also requires replacement of the entire head.

M20B20 owner needs to monitor the position of the timing gear and change it in time. Considering the age of the engine, the owner will have to deal with age-related problems. It is recommended to purchase another type of motor.

Modifications

There are several modifications to the engine.

1. Originally there was a motor with carburetor system. It was produced until 1981. It had a power of 120 horsepower at 6 thousand rpm, compression ratio was 9.2 to 1.
2. From 1981 to 1987, a version characterized by electronic injection L Jetronic was produced. It had a power of 125 horsepower with a compression ratio of 9.8. Maximum torque was reached at 4 thousand rpm – 170 Nm.
3. From ’82 through ’84, a mechanically injected version was available. The engine output was 126 horsepower, with a compression ratio of 9.9.
4. From ’85 to ’91, a direct injection version of the M20B20 was produced. Power was 129 horsepower at 6 thousand rpm.
5. From 1987 to 1992, the M20B20 was produced, characterized by electronic direct injection from Motronic. 8 to 1 compression. Maximum output is 129 horsepower.

Chip tuning

In order to increase the power of the engine it is recommended to increase its displacement. For this purpose it is necessary to install a crankshaft and connecting rods from M20B23, install a different cylinder-head gasket and rings. In this way you will be able to achieve a power of 150 horsepower. It is also possible to increase the volume to 2.8 liters. It is required to bore the cylinders to 84 millimeters, purchase a crankshaft from M52B28. The radiator will need to be replaced. Bore cylinders will significantly reduce the life of the motor, which does not exceed 100 thousand kilometers.

It is also possible to build a turbo based on the M20B20. This requires buying a Garret T04E kit, which has a turbo collector, intercooler, piping, downpipe. Replacement of connecting rods with 8.5 to 1 compression is required. Once the turbo package is installed the power will be around 370 horsepower.

This engine is installed on the following models:

BMW 3-Series (E30)

BMW 3-Series (E21)

BMW 5-Series (E34)