For decades, BMW has used a unique naming convention for their BMW engines, which can be quite confusing to non-BMW insiders. BMW labels codes their engines under the B, M, N, P or S. In the past, the BMW Engine Codes Naming Convention was certainly simpler than it is today. The M10 was reserved for the four-cylinder unit, the M20 for a low-powered six-cylinder and M30 for high-powered straight sixes.
But over the years, their fleet has expanded, as well as the engine offerings. Yet, some things remained consistent. The M Division labels their engines under the “S” code, while standard engines are categorized under the “M”, “N”, or “B” code. The Motorsport Racing division develops their units under the “P” code. Today, typical BMW engine codes are represented by a carefully ordered numbered and letters, which can be extremely useful for current and future BMW owners. You won’t only learn about your car’s specific power output and displacement, but it can also help you find replacement parts.
To simplify the decoding process, we put together a BMW Engine Naming Convention guide:
BMW M Engine Code
| M52B20TU | Engine Family |
| M | Standard Engines 1991 - 2005 |
| N | Standard Engines 2006 - 2016 |
| B | Standard Engines 2016 onward |
| S | BMW M Engines |
| P | BMW Motorsport racing engines |
| M52B20TU | Cylinders Count |
| 3 | Inline 3-cylinder |
| 4 | Inline 4-cylinder |
| 5 | Inline 6-cylinder |
| 6 | V8 |
| 7 | V12 |
| 8 | V10 |
| M52B20TU | Engine Variation |
| 0 | Original engine design |
| 1-9 | Major Updates |
| M52B20TU | Fuel Type |
| A | Benzine (gasoline), transverse mounted. Found in front-wheel drive based |
| B | Benzine (gasoline), longitudinally mounted. Found in rear-wheel drive |
| C | Diesel, transverse mounted. Found in front-wheel drive |
| D | Diesel, longitudinally mounted. Found in rear-wheel drive |
| E | Electric |
| G | Natural Gas |
| H | Hydrogen |
| M52B20TU | Displacement |
| 20 | 2.0 liter |
| 25 | 2.5 liter |
| 30 | 3.0 liter |
| 44 | 4.4 liter |
| M52B20TU | Technical Update |
| A revision to an existing engine design variant. "TU" stands for Technical Update |
The “N” Family of BMW Engines strayed from the initial logic and features some variations:
BMW N Engine Code
| N55B30T0 | Power Level |
| S | Super |
| T | Top |
| O | Obere (Upper) |
| M | Mittel (Medium) |
| U | Unterste (Lower) |
| K | Kleiner (Reduced) |
| 0 | New Development |
| N55B30T0 | Technical Update |
| 0 | Original engine design |
| 1-9 | Minor update to the original design |
BMW B Engine Code
It follows the same logic at the “N” BMW Engine Family it replaced.
BMW S Engine Code
Some of the previous BMW “S” engines had a simpler naming convention, like the famous S54B32. The S engine codes initially used the format of the M engine up to the S63 engine. But the latest units, such as the S55B30O0 in the current M3/M4, follows in the steps of the BMW “B” engines naming convention. Therefore, the same logic applies. There is also another exception: the W engine codes. If you see a BMW engine with a “W,” that means it was built by an external supplier.
