Knowledge Base
BMW B58 Engine — Complete Technical Guide
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
- B58B30M0 (2015-2018) — Original, direct injection only
- B58B30O1 (TU1) (2018+) — Added port injection, revised turbo, 3D-printed metal bracket
- 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.