The first car with an M20 engine was the BMW E12 520/6, which was fitted with a 2-liter M20B20 modification. The cylinder diameter is 80 mm, the piston stroke is 66 mm. The M20B20 engine was first equipped with a Bosch L-Jetronic injector in 1982 on a BMW 520i. In 1987 it was updated using a Bosch Motronic catalytic converter system.
M20 family: M20B20, M20B25.
Specifications
| Production years | 1977-1992 |
| Displacement, cc | 1991 |
| Fuel system | carburetor/injector |
| Power output, hp | 122/6000 125/5800 126/5800 129/6000 129/6000 |
| Torque output, Nm | 160/4000 170/4000 170/4000 174/4000 174/4300 |
| Cylinder block | cast iron R6 |
| Block head | aluminum 12v |
| Cylinder bore, mm | 80 |
| Piston stroke, mm | 66 |
| Compression ratio | 9.2 9.8 9.9 9.8 8.8 |
| Hydraulic lifters | no |
| Timing drive | belt |
| Turbocharging | no |
| Recommended engine oil | 5W-30 / 5W-40 / 10W-30 / 10W-40 / 10W-50 / 15W-50 |
| Engine oil capacity, liter | 4.25 |
| Fuel type | petrol |
| Fuel consumption, L/100 km (for E30 320i) — city — highway — combined |
13.0 7.5 9.5 |
| Engine lifespan, km | ~300 000 |
| Weight, kg | ~113 (dry) |
| Family | M20 |
| Oil consumption, gr/1000 km | up to 1000 |
The engine was installed on:
- BMW 3-Series E21 in 1977 – 1982, 3-Series E30 in 1982 – 1992;
- BMW 5-Series E12 in 1977 – 1981, 5-Series E28 in 1981 – 1987, 5-Series E34 in 1988 – 1990;
- Bertone Freeclimber 1 in 1989 – 1992.
Disadvantages of the BMW M20B20 engine
When using M20B20 engines, they face wear on the camshaft, overheating, and violation of the integrity of the cylinder head.
The cylinder head can move when overheated. To avoid cylinder head failure, at the first sign of overheating, you need to check the health of the cooling system. The system is checked for air pockets, which are removed by blowing. It is also necessary to assess the condition of the thermostat, pump and radiator.
Cylinder head may crack due to engine overheating. Often a crack occurs in the area of the 4-5 cylinder; the problem can be eliminated by replacing the part.
The condition of the timing belt and the location of the tensioner roller should be carefully monitored in order to avoid belt breakage, valve bending, piston breakage.
For motors with a range of 200 thousand kilometers or more, camshaft wear is characteristic, which is determined by a knock. To solve the problem, a new cylinder head is installed.
Frequently asked questions about the BMW M20B20
How much power does the BMW M20B20 make?
Power output of the BMW M20B20, hp: 122/6000; 125/5800; 126/5800; 129/6000; 129/6000. Torque, Nm: 160/4000; 170/4000; 170/4000; 174/4000; 174/4300.
How much oil does the BMW M20B20 take and which one?
Engine oil capacity: 4.25 liters. Recommended oil: 5W-30 / 5W-40 / 10W-30 / 10W-40 / 10W-50 / 15W-50.
Does the BMW M20B20 have a timing belt or chain?
The BMW M20B20 uses a timing belt.
Is the BMW M20B20 turbocharged?
No, the BMW M20B20 is naturally aspirated.
Does the BMW M20B20 need valve clearance adjustment?
Yes, there are no hydraulic lifters, so the valve clearances have to be checked and adjusted periodically.
How long does the BMW M20B20 last?
The typical lifespan of the BMW M20B20 is ~300 000 km with proper maintenance.
What is the fuel consumption of the BMW M20B20?
E30 320i: city 13.0, highway 7.5, combined 9.5 L/100 km.
What cars was the BMW M20B20 installed on?
BMW 3-Series E21 in 1977 - 1982, 3-Series E30 in 1982 - 1992; BMW 5-Series E12 in 1977 - 1981, 5-Series E28 in 1981 - 1987, 5-Series E34 in 1988 - 1990; Bertone Freeclimber 1 in 1989 - 1992.
What engines are related to the BMW M20B20?
M20 family: M20B25.
