BMW M20B27 Engine
This page lists the M20B27 specifications for the engine built by BMW.
| Fuel Type | Petrol |
|---|---|
| Configuration | I6 |
| Combustion Type | Naturally Aspirated |
| Displacement (cc) | 2,693 cc |
| Cylinders | 6 |
| Cylinder Bore (mm) | 84 mm |
| Cylinder Stroke (mm) | 81 mm |
| Valves | 12 |
| Valves Per Cylinder | 2 |
| Valvetrain | SOHC |
| Compression Ratio | 10.3:1 |
| Power (kW) | 95 kW @ 4,250 RPM |
| Torque (N⋅m) | 240 N⋅m @ 3,250 RPM |
| Redline (RPM) | 5,200 RPM |
| Weight (kg) | |
| Production | 1982 - 1988 |
| Cars Using Engine | 3 |
Where listed, power output figures are based on the most powerful production variant of that engine, because some manufacturers use different engine maps to tune the same engine for better fuel economy, performance or to differentiate models in the range.
The M20B27 was designed for efficiency (thus the e for the Greek letter eta in 325e) and low-rev torque. This was an unusual design strategy at the time for a BMW straight-six engine, which were usually designed for power at high RPM. The M20B27 used a 84 mm bore with a 81 mm stroke, resulting in a capacity of 2,693 cc. To reduce friction and improve efficiency, the M20B27 used the 200 version of the cylinder head with softer valve springs. Due to these changes, redline was reduced to 4,800 RPM. A compression ratio of 9.0:1 was used on the US 528e, and 11:1 on Euro 525e and 325e cars, which was reduced to 10.3:1 in 1985. The initial M20B27 produced 92 kW power at 4,250 RPM and 240 N⋅m torque at 3,250 RPM for models without a catalytic converter. Models with a catalytic converter produced 90 kW and 230 N⋅m of torque.
Since many markets tax cars based on engine displacement, the eta's larger displacement meant that it was not suitable for all markets. It was expressly developed with the American market in mind. BMW's corporate average fuel economy was at risk of not meeting requirements by 1984, primarily due to higher sales of their bigger, more expensive cars in the early 1980s. The first car to use the M20B27 was the US market 528e in 1982.
In late 1987, the fuel injection was upgraded to use Bosch Motronic 1.3 Engine Management. The cylinder head changed to the 885 design, the compression ratio was reduced to 8.5:1 and the redline increased to 5,200 RPM. Power output increased to 95 kW at 4,250 RPM, with torque remaining the same, 240 N⋅m at 3,250 RPM.
Cars using the BMW M20B27 Engine
There are 3 cars using this engine:
- BMW - 3 Series - E30 - 325e Saloon
- BMW - 3 Series - E30 - 325e Saloon
- BMW - 3 Series - E30 - 325e (94 kW) Saloon
Last Updated: 19th October 2020 at 20:57:43