Updated November 17, 2023

Are you a BMW enthusiast looking to upgrade your car or order the right parts? Understanding the different specifications of the B58 engine is crucial. BMW introduced the B-series of modular engines in 2016, but it went through major updates in 2018 and 2020. In this article, we will focus mostly on the B58 engine as it had the most changes and breakdown the different versions. So, let’s dive in and uncover the secrets of the B58 engine!

TL;DR – Which B58 Do You Have?

Knowing the specific B58 version you have can make all the difference when ordering parts or upgrades. Here’s a quick breakdown of the different B58 engine specs and the BMW models they are used in:

• B58A: “F” chassis BMW models – F22 M240i, F30 340i, F32 440i, G01 X3 M40i (2019), G02 X4 M40i (2019), and “early” models of 540i/740i/840i.
• B58C: “G” chassis BMW models that are not “M Sport” models – 2020+ G30 540i, G12 740i, G15 840i, G05 X5 40i, G06 X6 40i, G07 X7 40i. It is also used in the 2019-2020 Supra.
• B58D: “G” chassis BMW “M Sport” models – G42 M240i, G20 M340i, G22 M440i, G29 Z4 M40i, X3 M40i, X4 M40i, and 2020+ 540i/740i/840i. It is also used in the 2021+ Supra.
• B58N: “G” chassis BMW 5/7/X5/X6/X7-series models. This version is an evolution of the B58 and combines it with the 48V Mild Hybrid system found in V8 models.

Background of the B58 Engine

The B-series engines were designed to be modular, with shared components between the 4-cylinder and 6-cylinder engines. However, BMW made three iterations of the B58 engine in just five years, and only small items like sensors and hardware were shared among them. Furthermore, BMW has an abundance of abbreviations for their engine specs, creating confusion for insiders and enthusiasts alike. With that said, let’s decode some of these shorthand abbreviations and understand the different changes along the way.

Model Year Changes

The B46 4-cylinder engine remained largely unchanged from 2016-2019, but it was updated to the B46D spec with significant changes for the 2020 model year. On the other hand, the B58 engine had multiple iterations and different models used each version. To help you keep track, we have laid out the model changes in a helpful chart.

Specific Changes – What’s Different in Each Version?

The B58 engine went through significant changes over the three iterations. Let’s explore some of the differences we know about:

Crankshaft

The C/D version of the B58 engine features a 2.3lbs lighter crankshaft due to the use of lighter materials and different machining.

Timing Chain

The C/D version of the B58 engine uses a 1-piece timing chain instead of a 2-piece setup. The new design simplifies the chain drive system, eliminating the need for two camshaft sprockets and several guide rails and tensioners.

VANOS Cam Gears

Due to the changes in the timing chain, the cam gears on the VANOS system are also different in the C/D version.

Serpentine Belt

The revised cooling system and engine accessory layout led to changes in the serpentine belt. The new belt is shorter and requires fewer deflection pulleys. Other components in the belt drive system, such as the crankshaft vibration dampener, water pump, and A/C compressor, also underwent changes.

Cooling System

The C/D versions of the B58 engine feature an innovative cooling design with separate zones for the cylinder head and engine block. This allows for better control of coolant flow and temperature regulation, improving engine performance and efficiency.

Fuel Injectors

Each engine variant of the B58 engine has its own fuel spray pattern and pressure specifications.

Engine Computer

Each B58 version uses a different Engine Control Unit (ECU) to optimize performance and functionality.

Cylinder Head-Exhaust Manifold-Turbo

The B58C version, used in the 2020+ 540i, 740i, 840i, X5, X6, and X7 “40i” models, features an internal exhaust manifold integrated into the cylinder head. This unique design improves exhaust gas temperature and fuel efficiency. However, BMW reverted to a traditional exhaust manifold for the B58D engine used in “M Sport” models.

B58C 48 Volt Mild Hybrid System

Starting from 2021, the B58C engine in the 5/7/8-series is available with an optional 48-volt mild hybrid system. This system combines an electric motor into the alternator, battery, and belt drive system, allowing for partial engine shutdown during certain low-load situations. This enhances fuel economy and reduces emissions while providing an instant power boost when needed.

B58N 48 Volt Hybrid Drive System

In some 2022 models, BMW released a new version of the 48-volt Mild Hybrid system, known as the Hybrid Drive system. This system, integrated into the ZF 8HP transmission, provides 48-volt power through the torque converter. It offers similar efficiency benefits to the mild hybrid system but operates in normal forward drive at low speeds as well.

B46 vs B48 – Why Two Versions?

You might be wondering why there are two versions of the 4-cylinder engine. The B46 is the standard Super Ultra Low Emissions spec (SULEV) engine used in most US market BMW models. However, BMW wanted a performance-spec engine for special models like the X2 M35i and the MINI John Cooper Works, which led to the development of the B48 engine. The B48 engine features various performance enhancements and improvements over the standard B46 engine.

Z4 vs Supra – What’s the Difference?

The BMW Z4 and Toyota Supra share the same platform and engine. However, there are some differences between the two. The G29 Z4 M40i always used the B58D engine, while the Supra initially used the B58C engine in its 2020 model. However, for the 2021 model year, the Supra was upgraded to the B58D engine. The B58D engine offers higher output and revised performance compared to the B58C engine.

And there you have it! A comprehensive breakdown of the various versions of the B58 engine. Now you can confidently identify which B58 engine your BMW has and make informed decisions when it comes to upgrades and maintenance. If you want to learn more about BMW engine codes, check out our detailed guide on our website MMSPLAY.

Remember, knowledge is power when it comes to your beloved BMW!

Disclaimer: The information provided in this article is based on our research and knowledge. We strive to present accurate and up-to-date information; however, we recommend consulting official BMW resources and experts for precise details.