BMW

On a BMW, it is the engine code — not the engine capacity — that determines which part is compatible.

A 2.0d may come with a M47D20, a N47D20 or a B47D20 depending on the generation and model: three distinct engine families, three different turbos, three gearboxes that cannot be swapped for one another. The same logic applies to the 3.0d, where the M57D30, N57D30 and B57D30 families coexist — and the suffixes (A, B, C…) are not trivial: an N57D30A and an N57D30C do not share the same characteristics. The engine code, visible on the block itself or in the manufacturer's documentation, is the only reliable starting point before searching for any part.

Turbos, engines, gearboxes: what the BMW collection covers

The collection spans sixteen models from the Série 1 to the M5, X1 to X6, Z4 and Série 2 Gran Tourer, covering model years from 1999 to 2024. It is divided into four families: turbo (the largest family), bare engine, gearbox and transfer case (the latter applies to xDrive and 4-wheel drive versions — X3, X4, X5 and X6 in particular). The Série 3 is the most represented model, followed by the Série 1 and the Série 5. Parts are available on an exchange basis or, for certain references, as a rebuild of your own unit.

Diesel and petrol: the engine code families you need to know

On the diesel side, the N47D20x (Série 1, 3, 5, X1, X3 — 2.0d) and N57D30x (X3, X5, Série 5 and 7 — 3.0d) codes account for the vast majority of reconditioned turbo and engine references. M47 blocks feature on earlier generations (E46, early E90). On the petrol side, the 2.0i and 3.0i draw on several families: N20B20, B48B20, N54B30, N55B30A, B58B30 — each tied to a specific generation and its own set of parts. The 335i and 335xi are a good illustration of the risk of confusion: depending on the year, the engine may be an N54B30A, N54B30B or N55B30A. Always identify your engine code before browsing the sub-categories.