BMW B58 Tuning Guide — M140i, M240i, 340i, 440i & More | Wayside Performance
The BMW B58 is arguably the finest turbocharged engines BMW has ever built, and one of the best tuning platforms on the market at any price. A five-time Ward's 10 Best Engines winner and it's the engine Toyota chose for the A90 Supra, which tells you everything you need to know about its reputation.
From the compact M140i to the 7 Series, it delivers the signature straight-six smoothness that BMW is famous for, combined with extraordinary tuning potential.
What makes the B58 so special from a tuning perspective is its mechanical strength.
Unlike its N55 predecessor, the B58 uses a closed-deck aluminium block, the same casting as BMW's B57 diesel, engineered to handle the enormous combustion pressures of a compression-ignition engine.
The crankshaft is forged steel, the connecting rods are drop-forged, and the whole assembly is reinforced with a complex array of internal ribs.
These internals are proven to handle power levels far beyond what BMW runs from the factory — up to 600–650whp on stock internals is widely ran on stock engines across the world.
The factory power output is also significantly underrated. BMW quotes 340bhp, but ours and many others consistently dyno these at 360hp+.
The good news is that the conservative factory calibration leaves an enormous amount of performance locked away in the ECU, and a remap is the single most effective way to unlock it.
This guide covers three stages of tune for the B58 platform, with our recommended hardware at each level. Every remap is a custom dyno calibration carried out on our in-house rolling road.
The B58 EngineWhy it's so good — and why it tunes so well
The B58 is a 3.0-litre (2,998cc) turbocharged inline-six with an 82mm bore and 94.6mm stroke. It's a long-stroke design, which gives it excellent low-down torque characteristics and that distinctive straight-six surge that builds relentlessly through the mid-range.
The compression ratio is 11.0:1 — high for a turbocharged engine — and the redline sits at 7,000rpm.
The turbocharger is a single twin-scroll design, using the exhaust pulses from pairs of cylinders to spool the turbine more efficiently. This gives the B58 significantly virtually no turbo lag as boost builds early and response is immediate.
The intercooler is an integrated water-to-air design, mounted directly in the intake plenum rather than as a separate unit. This keeps the charge air path as short as possible, reducing volume between the turbo and the cylinders for sharper response.
The engine management uses BMW's MEVD17.2.G ECU, with Double VANOS (variable valve timing on both intake and exhaust cams) and Valvetronic (continuously variable valve lift).
This gives us an enormous number of parameters to work with during calibration, it's not just boost and timing, it's the entire way the engine breathes and delivers power.
The combination of a closed-deck block, forged rotating assembly, efficient turbocharger and sophisticated engine management makes the B58 one of the most rewarding engines to tune.
The hardware has headroom for far more power than the factory delivers, and the ECU gives us the tools to extract it safely.
Stage 1 — 420–435bhpRemap only — no hardware required
Stage 1 is a remap only, no hardware changes are required.
With a full recalibration of boost pressure, ignition timing, VANOS cam timing, fuelling and wastegate duty cycle, we extract 420–435bhp and 450–460ft/lb from the standard engine and turbocharger.
That's a gain of almost 100bhp over BMW's quoted figure — on a completely standard car.
The B58 responds to a Stage 1 remap like very few other engines. The closed-deck block and forged internals mean the hardware is comfortably within its safe operating window at this power level.
The integrated water-to-air intercooler is very efficenet and keeps intake temps well controlled, and the twin-scroll turbo has plenty of headroom to deliver more boost without being pushed anywhere near its efficiency limit.
The result is a car that feels like it should have come from the factory this way. The power delivery remains smooth and progressive, maintains that signature straight-six surge, just with considerably more of it.
Throttle response sharpens up, the turbo builds boost faster, and the top-end pull becomes addictive.
- ZF gearbox calibration — raises torque limits and sharpens shifts
- NGK spark plugs — fresh plugs gapped for increased boost
- 99 RON fuel — Shell V-Power or Tesco Momentum
Stage 2 — 440–455bhpPerformance downpipe + panel filter required
Stage 2 removes the biggest restriction on the B58, the factory downpipe and catalytic converter. The stock downpipe is extremely restrictive, and replacing it with a free-flowing 5" performance unit allows the twin-scroll turbo to exhale properly. Combined with a high-flow panel filter and a revised ECU calibration optimised for the improved airflow, we extract 440–455bhp and 480–500ft/lb of torque.
The gains over Stage 1 go beyond peak numbers. Turbo response sharpens noticeably, the turbo spools faster with less backpressure to fight against, and the top-end pull extends right to the redline rather than tailing off.
The B58 is famously quiet from the factory, and a performance downpipe brings the exhaust note to life with a much more purposeful sound under load.
The B58's forged internals still remain comfortably within their safe operating window at Stage 2 power levels, and the factory fuel system has no issues keeping up. This makes Stage 2 one of the best value performance upgrades available, a relatively simple hardware change paired with a revised calibration delivers a genuine step up in performance and driving experience.
- Performance downpipe — 4 or 5" decat or sports cat
- High-flow performance panel filter
- 99 RON fuel — Shell V-Power or Tesco Momentum
Stage 2+ — 470–500bhpDownpipe + HPFP upgrade + panel filter required
Stage 2+ pushes the stock B58 turbocharger to its absolute ceiling. With a performance downpipe, uprated high-pressure fuel pump and panel filter, we can extract 470–500bhp and 515–530ft/lb — the maximum the factory turbo can safely deliver on 99 RON pump fuel.
The HPFP upgrade is the key unlock at this level. Beyond Stage 2 power, the factory high-pressure fuel pump can't deliver enough fuel to keep the engine safe under full load at higher boost levels.
The fuel system becomes the limiting factor, not the turbo or the internals. Upgrading to a higher-flowing pump, the B58TU (Supra) HPFP is a direct bolt-on upgrade and solves this completely, allowing us to run even more boost, safely.
Even at Stage 2+ power levels, the B58's forged crankshaft, forged connecting rods and closed-deck block are well within their proven limits. We're still operating within a comfortable mechanical safety margin. The stock intercooler also continues to perform well at this level, though intake temps should be monitored during sustained hard use or track driving.
- Performance downpipe — 5" decat or sports cat
- Uprated high-pressure fuel pump (HPFP)
- High-flow performance panel filter
- 99 RON fuel — essential at this power level
- Upgraded chargepipe — the stock plastic pipe can crack under increased boost
- ZF gearbox calibration — essential to remove torque limits at this power level
- NGK 94201 spark plugs — gapped for increased boost
Keeping Your B58 HealthyMaintenance tips for tuned B58 engines
The B58 has an excellent reputation for reliability — arguably the best of any turbocharged BMW engine. But like any high-performance engine, it benefits from proper maintenance.
Oil: Use a quality fully synthetic 5W-30 or 5W-40 from a reputable brand (Liqui Moly, Millers, Motul). BMW's long-life service intervals are far too generous for a tuned car — we recommend changing oil every 5,000–7,500 miles. The B58 is a direct-injection engine and fuel dilution of the oil is a real phenomenon over extended intervals.
Spark plugs: The factory spark plugs can misfire under increased boost. We recommend NGK iridium plugs, gapped to suit your power level. Replace every 15,000–20,000 miles on a tuned car. Fresh, correctly gapped plugs make a noticeable difference to smooth power delivery and knock resistance.
Carbon buildup: Like all direct-injection engines, the B58 is susceptible to carbon buildup on the intake valves over time. Without port fuel injection to wash the backs of the valves, carbon deposits gradually accumulate and can eventually cause rough idle, reduced performance and misfires. A walnut blast clean every 40,000–60,000 miles is good preventative maintenance.
Chargepipe: The factory plastic chargepipe is a known weak point on tuned B58s. Under increased boost pressure, the stock pipe can crack or blow off entirely. If you're running Stage 2 or above, an upgraded aluminium chargepipe is a sensible investment. Even at Stage 1, it's worth inspecting periodically.
Cooling system: The electronic water pump and thermostat can fail — this is a known BMW issue across multiple platforms. Keep an eye on coolant temps and address any fluctuations promptly. The oil filter housing gasket and valve cover gasket are also common leak points as the car ages — neither is a major concern, but both should be addressed when they appear.
Fuel: Always run 99 RON — Shell V-Power or Tesco Momentum. The B58's high compression ratio (11.0:1) makes it sensitive to fuel quality, especially when tuned. At Stage 2+ power levels, 99 RON is essential.
Applicable ModelsEvery BMW fitted with the Gen 1 B58 engine
| Model | Chassis Code | Years | Drive |
|---|---|---|---|
| M140i | F20 / F21 | 2016–2019 | RWD |
| M240i | F22 / F23 | 2016–2021 | RWD / xDrive |
| 340i | F30 / F31 | 2015–2019 | RWD / xDrive |
| 440i | F32 / F33 / F36 | 2016–2020 | RWD / xDrive |
| 540i | G30 / G31 | 2017–2020 | RWD / xDrive |
| 740i | G11 / G12 | 2016–2019 | RWD / xDrive |
The B58TU (Gen 2) found in the M340i, M440i, Z4 M40i and Toyota Supra uses updated hardware including a higher-flowing HPFP, revised intercooler and single-piece timing chain. Contact us for Gen 2 specific tuning.
Complete the LookStyling upgrades for your M140i / M240i
The M140i and M240i are understated cars from the factory — which is part of their appeal. But a few well-chosen styling upgrades can sharpen things up without losing the sleeper aesthetic. Whether it's a subtle lip spoiler, gloss black grilles, or mirror caps, the right touches complement the extra performance without shouting about it.
Quick ReferenceAt-a-glance comparison of each stage
| Stage | Power | Torque | Hardware Required |
|---|---|---|---|
| Stock | 335bhp (underrated) | ~330ft/lb | — |
| Stage 1 | 420–435bhp | 450–460ft/lb | None (remap only) |
| Stage 2 | 440–455bhp | 480–500ft/lb | 5" downpipe + panel filter |
| Stage 2+ | 470–500bhp | 515–530ft/lb | 5" downpipe + HPFP + panel filter |
*All figures measured on our in-house dyno using 99 RON fuel. Individual results may vary based on vehicle condition, ambient temperature and fuel quality. Figures apply to Gen 1 B58 models.
