BMW B58 Engine — Complete Technical Guide

Overview

The B58 is BMW's modular 3.0-liter single-turbocharged inline-six, introduced in 2015 as the successor to the N55. It represents BMW's latest generation of straight-six engineering and is widely regarded as one of the best engines BMW has ever produced. Internal code: B58B30.

Key Specifications:

• Displacement: 2,998 cc
• Bore x Stroke: 82.0 mm × 94.6 mm
• Compression Ratio: 11.0:1
• Max Power: 340 hp (250 kW) @ 5,500 rpm (B58B30M0, M340i spec)
• Max Torque: 500 Nm (369 lb-ft) @ 1,520–4,800 rpm
• Redline: 7,000 rpm
• Fuel System: Combined direct + port injection (from TU1 revision)
• Turbocharger: Single twin-scroll BorgWarner B03
• Engine Management: Bosch MG1CS003 (MEVD17.2.G)

Architecture & Design

The B58 is part of BMW's modular engine family (CLAR platform). It shares its 500cc-per-cylinder architecture with the B48 (4-cylinder) and B38 (3-cylinder). The block is aluminum with an integrated exhaust manifold in the cylinder head — a key design change from the N55.

Key Design Differences vs N55

• Integrated exhaust manifold — built into the cylinder head, reduces turbo lag and improves emissions warm-up
• Closed-deck block — stronger than the N55's open-deck design
• Longer stroke — 94.6mm vs 89.6mm, more torque-oriented
• Higher compression — 11.0:1 vs 10.2:1
• Port injection added (TU1 revision) — eliminates carbon buildup on intake valves

B58 Revisions

1. B58B30M0 (2015-2018) — Original, direct injection only
2. B58B30O1 (TU1) (2018+) — Added port injection, revised turbo, 3D-printed metal bracket
3. S58 — M division variant with twin turbos, forged internals (M3/M4 G80/G82)

Turbo System

The B58 uses a single twin-scroll turbocharger. The twin-scroll design separates exhaust pulses from cylinders 1-3 and 4-6 into separate scrolls, reducing interference and improving spool.

Turbo Specs (B03):

• Compressor: ~52mm inducer
• Turbine: ~49mm
• Max boost (stock): ~1.2 bar (17.4 psi) on overboost
• Electronic wastegate — precise boost control via DME

Fuel System (TU1 Dual Injection)

The TU1 revision added a secondary port injection system alongside the existing direct injection. This is a game-changer:

• Direct injection — Bosch HDEV6 solenoid injectors, up to 350 bar
• Port injection — Low-pressure injectors in the intake manifold
• Strategy — Port injection used at low loads to keep intake valves clean; direct injection at high loads for power

This dual system virtually eliminates the carbon buildup problem that plagued the N54 and N55.

Common Problems & Solutions

The B58 is remarkably reliable compared to its predecessors, but it's not immune:

1. Coolant Loss / Thermostat Failure

• Frequency: Moderate, typically 60,000-100,000 km
• Cause: Electronic thermostat housing cracks or thermostat fails
• Solution: Replace thermostat assembly. OEM or Wahler replacement.

2. VANOS Solenoid Issues

• Frequency: Uncommon but documented
• Symptoms: Rough idle, reduced power, VANOS fault codes
• Solution: Replace VANOS solenoids. Clean oil feed lines.

3. Charge Pipe Cracking (Pre-TU1)

• Frequency: Moderate on tuned cars
• Solution: Aftermarket aluminum charge pipe

4. Oil Filter Housing Gasket Leak

• Frequency: Less common than N54/N55 but still occurs
• Solution: Replace gasket, check for warping

Tuning Potential

The B58 responds extremely well to tuning, with the closed-deck block and robust internals:

Stage	Typical Power	Typical Torque	Key Mods
Stock	340 hp	500 Nm	—
Stage 1	400-420 hp	560-600 Nm	ECU tune only
Stage 2	450-480 hp	640-680 Nm	Downpipe + tune
Stage 2+	500-550 hp	720-780 Nm	Full bolt-ons + E85
Big Turbo	650-800+ hp	850+ Nm	Turbo upgrade + built trans

Note: The ZF 8HP transmission is typically the weak point before the engine. Above ~650 Nm, a transmission build or upgraded clutch packs are recommended.

Applications

• 2016+ BMW 340i / M340i (G20/G21)
• 2016+ BMW 440i / M440i (G22/G23/G26)
• 2017+ BMW 540i / M540i (G30/G31)
• 2017+ BMW 740i (G11/G12)
• 2018+ BMW X3 M40i / X4 M40i (G01/G02)
• 2018+ BMW Z4 M40i (G29)
• 2020+ Toyota Supra 3.0 (A90/A91) — B58B30 variant

The B58 is BMW's masterpiece of modern inline-six engineering — refined, powerful, and incredibly tunable.