BMW B58 3.0T Engine Guide — Supra A90, M240i, M340i, 540i

The BMW B58 is arguably the most important inline-six BMW has produced since the legendary 2JZ-GTE era of Toyota collaboration — and ironically, it now powers a Toyota. A 3.0-liter single-turbocharged inline-six, the B58 is the performance backbone of BMW's non-M lineup and the heart of the Toyota GR Supra A90. Found in everything from the M240i and M340i to the 540i and Z4 M40i, the B58 is one of the most tunable platforms on the market today. This guide covers the architecture, Gen 1 vs Gen 2 differences, tuning stages, known issues, and the supporting mods you need at each power level.

B58 Architecture & Design

The B58B30 is a 2,998 cc single-turbocharged inline-six that replaced the N55 starting in 2016. It shares the same modular engine family (CLAR platform) as the B48 four-cylinder, but with two additional cylinders and a fundamentally different approach to boost delivery.

Key architecture highlights:

• Closed-deck aluminum block — same closed-deck philosophy later carried into the S58, giving the B58 exceptional cylinder wall rigidity for a non-M engine
• Single twin-scroll turbocharger — a single large-frame turbo with twin-scroll housing, fed by a tubular exhaust manifold integrated into the cylinder head
• Electric wastegate — electronically controlled wastegate for precise boost control and faster transient response compared to the N55's pneumatic wastegate
• Indirect charge air cooling — water-to-air intercooler integrated into the intake manifold (same concept as the S58)
• Valvetronic & Double-VANOS — variable valve lift and timing on both intake and exhaust
• Direct injection at 350 bar — high-pressure direct injection with solenoid injectors (Gen 1) or piezo injectors (Gen 2)

The B58's closed-deck block is the critical detail that separates it from the N55 and makes it a legitimate tuning platform. The N55's open-deck block limited safe power output to roughly 450-500 HP before cylinder wall deflection became a concern; the B58 pushes that ceiling past 600 HP on stock internals.

B58 Gen 1 vs. Gen 2

BMW produced two distinct generations of the B58, and the differences matter for tuning:

Gen 1 — B58B30O1 (2016-2018)

• Found in: F30 340i, F32 440i, G30 540i (early), G29 Z4 M40i (early), F15 X5 40i
• Solenoid fuel injectors
• Cast exhaust manifold integrated into head
• Port injection added on some variants

Gen 2 — B58B30M1 (2019+)

• Found in: A90 GR Supra, G42 M240i, G20 M340i, G30 540i (late), G01 X3 M40i
• Piezo fuel injectors (higher flow rate, more precise atomization)
• Revised turbocharger with improved compressor wheel
• Updated exhaust manifold design
• Strengthened connecting rods
• Revised oil supply system

The Gen 2 B58 is the stronger platform for tuning. The piezo injectors support higher fuel flow rates (critical for Stage 2+), the strengthened rods increase the safety margin on stock internals, and the revised turbo compressor wheel flows more air. Gen 1 cars are still very tunable but hit fuel system limitations sooner.

Stock Power Output by Variant

• 340i / 440i / 540i / 640i (Gen 1): 335 HP / 332 lb-ft
• M340i / M440i (Gen 2): 382 HP / 369 lb-ft
• M240i (Gen 2): 382 HP / 369 lb-ft
• Toyota GR Supra 3.0 (Gen 2): 382 HP / 368 lb-ft (2021+; early 2020 models made 335 HP)
• Z4 M40i: 382 HP / 369 lb-ft

Like the S58, B58 power differences across variants are largely calibration-based. The hardware is the same — BMW simply adjusts boost targets and fueling in the ECU.

B58 Tuning Stages — What to Expect

Stage 1 — ECU Calibration Only (~420-450 HP)

A Stage 1 tune raises boost targets, optimizes ignition timing, and adjusts fuel maps. On the Gen 2 B58, expect 420-450 HP and 440-470 lb-ft on 93 octane. Gen 1 cars see slightly less — roughly 400-420 HP — due to the lower-flow solenoid injectors.

The B58 Stage 1 tune is one of the best bang-for-buck modifications in the entire BMW lineup. The torque increase is immediately noticeable, and the power delivery remains smooth and linear. Shop GR Supra A90 tuning and parts

Stage 2 — Downpipe + Tune (~480-520 HP)

Stage 2 adds a catless or high-flow catted downpipe to reduce exhaust backpressure from the single turbocharger. Combined with a Stage 2 calibration, expect 480-520 HP and 500-540 lb-ft on pump fuel.

The B58's single-turbo layout means the downpipe is a single unit (unlike the S58's twin downpipes), making this upgrade more straightforward and less expensive. An upgraded charge pipe and intake are recommended at this stage. For a full comparison of downpipe options, read our B58 downpipe guide.

Stage 3 — Turbo Upgrade / Full Build (600+ HP)

The stock B58 turbocharger begins to run out of efficiency around 520-540 HP. Beyond this point, a turbo upgrade is required:

• Hybrid turbo: A larger compressor wheel on the stock turbo frame, typically supporting 550-650 HP depending on the hybrid specification
• Full turbo kit: A complete aftermarket turbocharger (BorgWarner EFR or Garrett G-series based kits are common), pushing 700-800+ HP with forged internals and fuel system upgrades
• Port injection: Supplemental port injection is critical at Stage 3 to support the fueling demands that exceed the direct injection system's capacity

At the Stage 3 level, forged connecting rods and pistons become advisable — the Gen 2 B58's stock rods are robust, but sustained operation above 600 HP pushes them beyond comfortable safety margins.

B58 vs. S58 — The Relationship

The S58 is not simply a "tuned B58" — it is a ground-up redesign that shares the B58's displacement and basic architecture but differs in nearly every critical component:

• Twin turbo vs. single turbo: The S58 uses two mono-scroll turbochargers; the B58 uses a single twin-scroll unit
• Forged crank vs. cast: The S58 has a forged crankshaft; the B58 uses a cast unit (still strong, but with a lower ceiling)
• Valvetrain: Different camshaft profiles and valve springs for higher-RPM operation
• Oil system: The S58 has a dedicated oil pump and higher-capacity oiling for sustained track use

For tuning purposes, the practical ceiling on the B58 with stock internals is roughly 550-600 HP, while the S58 can reach 800+ HP before internal upgrades become mandatory.

Known Weak Points & Common Issues

• Coolant transfer pipe / hose: The B58 has a plastic coolant pipe that runs along the back of the engine block. This pipe is known to crack and leak, especially on higher-mileage engines or those subjected to repeated heat cycles. Replacement with an aluminum aftermarket unit is a common preventive maintenance item.
• VANOS solenoids: The B58's VANOS solenoid seals can deteriorate over time, causing fault codes and rough idle at cold start. Replacement solenoids with improved seals are available.
• Charge pipe: Like the S58, the B58's factory plastic charge pipe is a weak point under increased boost. An aluminum replacement is a must with any tune.
• Valve cover gasket: Oil seepage from the valve cover gasket is relatively common after 60,000+ miles, particularly on Gen 1 cars.
• Electric wastegate actuator: The electronic wastegate can occasionally throw fault codes due to actuator calibration drift. A re-learn procedure through diagnostic software typically resolves this without part replacement.

Supporting Modifications by Stage

Stage	Required Mods	Recommended Mods
Stage 1	ECU tune only	Charge pipe, intake
Stage 2	Downpipe, charge pipe, ECU tune	Intercooler upgrade, intake, BOV
Stage 3	Turbo upgrade, downpipe, fuel system, ECU tune	Forged internals, port injection, oil cooler, transmission cooler

Remote ECU Tuning — How It Works

YPG Motorsport offers remote ECU calibration for the B58 platform worldwide — both Gen 1 and Gen 2 variants, including the Toyota GR Supra A90. The process is straightforward:

1. Purchase your tune from our store and receive an OBD flash tool by mail
2. Read your stock file using the tool and send it to our calibration team
3. Receive your custom calibration — built specifically for your car's hardware, fuel quality, and altitude
4. Flash the tune to your ECU
5. Data log and refine — we review your logs and adjust at no extra cost

Every B58 calibration is custom-built. We account for your specific generation (Gen 1 or Gen 2), installed hardware modifications, available fuel octane, and altitude. Browse our full lineup of GR Supra A90 performance parts and tuning.

Bottom Line

The B58 is BMW's most versatile and tunable non-M inline-six ever produced. The closed-deck block, electronic wastegate, and water-to-air intercooler give it a mechanical foundation that the N55 never had. Whether you're unlocking 420 HP with a simple Stage 1 flash on your M340i or building a 700+ HP GR Supra with a full turbo kit, the B58 has the architecture to support it. The Gen 2 variant is the stronger platform, but both generations respond remarkably well to calibration work.