BMW Engine Designations Explained

BMW M760Li xDrive V12 N74B66TU

S63B44T3, N55B30T0, M10B18, S65B40, M20B27. Gibberish internal engineering codes never intended for public consumption, right? Not so. For the well-versed among us, the aforementioned list of BMW engine codes or designations conjures up distinct images of different cars and their power plants. But what does it all really mean? Most of us have the basics down, like the first two numbers being the overarching series of the engine, followed by a B for some reason, and then the displacement. TU, or simply T these days, stands for technical update, but what about all of those other numbers? And where do they derive the meanings for the engine series number and the various letters to begin with? If you’ve ever pondered these questions, read on.

BMW M10 Twin Solex

For what we estimate to be roughly the previous four decades, BMW has used the same basic naming scheme. A number of resources provide visual breakdowns with legends and keys that explain what each character in the sequence means, but it’s easy to get lost in the details. Here’s a quick breakdown of the TwinPower six-cylinder engine used in the last generation of -35i suffix models:

N55B30M0

N Engine Family, N — New Generation BMW Engines from approximately 2001 until 2014
5 Cylinder Count, 5 = 6
5 Technical Highlight, 5 — Turbocharged and Direct Injection with Valvetronic
B Fuel Type, B — Benzine (gasoline)
30 Displacement, 30 = 3.0 Liters
M Power Level, M — Mittel (Middle)
0 Revision Number, 0 — Original Design

BMW N55 3.0 Liter TwinPower Turbo Inline Six

And here’s the broader explanation of what could fill each select space in the sequence of a BMW engine code. Things are always changing in the automotive world with new technologies succeeding old ones, and as such, BMW has had to update how they name engines over the years slightly as well. We’ve included all the details below:

Engine Family

B Modular Engines, beginning in 2014 with B48
N New Generation BMW Engines from approximately 2001 (with N40) until 2014
M Conventional BMW Engine From 1970’s until early-2000’s
S M Engine for road car application
P M Engine for Motorsport racing application
W Engine shared with another manufacturer.

Cylinder Count

(Used since approximately the late 1980’s with more recent changes noted within table)

1 Inline Four Cylinder
2 Inline Four Cylinder (Since approximately 2011)
3 Inline Three Cylinder (Since approximately 2014)
4 Inline Four Cylinder
5 Inline Six Cylinder
6 V8
7 V12
8 V10

Engine Update Number / Technical Highlight Digit

Previous Meaning:

0 Original Engine design
1 First Major Update
2 Second Major Update
3 Third Major Update
4 Fourth Major Update

Intermediate Meaning:

0 Original Engine Design
1 SULEV with Valvetronic
2 Valvetronic
3 Valvetronic with Direct Injection
4 Turbocharged Direct Injection with Double VANOS
5 Turbocharged Direct Injection with Valvetronic
6 SULEV with Valvetronic (four cylinder)
7 Turbodiesel Direct Injection

Current Meaning:

6 SULEV Turbocharged with Valvetronic and Direct Injection
7 Turbodiesel Direct Injection
8 Turbocharged with Valvetronic and Direct Injection

Fuel Type / Engine Layout

Previous Meaning:

B Benzine (gasoline)
D Diesel
E Electric
G Natural Gas
H Hydrogen

Current Meaning

A Gasoline, Transverse Mounting
B Gasoline, Longitudinal Mounting
C Diesel, Transverse Mounting
D Diesel, Longitudinal Mounting
K Gasoline, Mid-Mounted

Displacement Examples

18 1.8 Liters
27 2.7 Liters
30 3.0 Liters
32 3.2 Liters
40 4.0 Liters
44 4.4 Liters
48 4.8 Liters
66 6.6 Liters

Power Level

S Super
T Top
O Obere (Upper)
M Mittel (Medium)
U Unterste (lower)
K Kleiner (Reduced)
0 New Development

Revision

0 Original Engine design
1 First Major Update
2 Second Major Update
3 Third Major Update
4 Fourth Major Update

BMW F90 M5 S64B44T4

Confused? That’s understandable at first, but given some time, the language really does make sense. Take an older design like the M10B18 found in the E21 320i or early E30 318i. Decoding this one is pretty simple:

M10B18

M Standard Engine Family, pre early-2000’s
1 Inline Four Cylinder
0 Original Design
B Fuel Type, B — Benzine (gasoline)
18 Displacement, 18 = 1.8 Liters

 

But how about something more complex and difficult, like comparing the N63 of the M850i to the S63 of the F90 M5? Note that things have been updated since the N63 and S63 were initially released, and the technical highlight digit lacks a rather important detail relating to the engine being turbocharged.

G15 M850i, N63B44T3

N New Generation BMW Engines from approximately 2001 until 2014
6 Cylinder Count, 6 = V8
3 Valvetronic With Direct Injection
B Fuel Type, B — Benzine (gasoline)
44 Displacement, 44 = 4.4 Liters
T Power Level, T — Top
3 Revision Number, 3 — Third since N63 was released in 2008

F90 M5, S63B44T3

S M Engine for road car application
6 Cylinder Count, 6 = V8
3 Valvetronic With Direct Injection
B Fuel Type, B — Benzine (gasoline)
44 Displacement, 44 = 4.4 Liters
T Power Level, T — Top
4 Revision Number, 4 — 4th since release

And for one final comparison, we’ll look at the difference between the initial B58 release, and the most potent version that’s going to be used in the upcoming Z4 M40i and M340i.

B5830M0 (F32 440i, F30 340i)

B Engine Family, B — Modular Engines, beginning in 2014
5 Cylinder Count, 5 = 6
8 Technical Highlight, 8 — Turbocharged with Valvetronic and Direct Injection
B Fuel Type, Mouting, B — Gasoline, Longitudinal Mounting
30 Displacement, 30 = 3.0 Liters
M Power Level, M — Mittel (middle)
0 Revision Number, 0 — Original Design

B5830O1 (G29 Z4 M40i US-Spec)

B Engine Family, B — Modular Engines, beginning in 2014
5 Cylinder Count, 5 = 6
8 Technical Highlight, 8 — Turbocharged with Valvetronic and Direct Injection
B Fuel Type, Mouting, B — Gasoline, Longitudinal Mounting
30 Displacement, 30 = 3.0 Liters
O Power Level, O — Obere (upper)
1 Revision Number, 1 — First Revision

But it wasn’t always this way. The M20 was originally internally referred to as the M60 before the quad-cam V8 arrived in 1992, and the M30 was initially called the M06. The M10 is another story on its own, as before it entered to the Bosch fuel-injected era, it was designated under a variety of different codes like M05, M115, M118 and so on.—Alex Tock

[Photos courtesy BMW AG, Alex Tock.]

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