BMW B58 · 3.0 Turbo Straight-Six

420bhp on Stage 1
450 on Stage 2

The B58 is the best engine BMW currently build — and it leaves the factory with a great deal left in it. We tune every car it went into, on our own 4WD dyno, with the map written for your car rather than pulled off a shelf.

Book Your B58 In See Your Exact Figures

Every B58 car, and what it makes

Stage 1 figures are typical results for a healthy, standard car on our dyno. Stage 2 needs supporting hardware — see below. Prices are inc VAT for Stage 1 custom dyno tuning.

Car	Standard	Stage 1	Stage 2	Price	+ Gearbox
BMW M140iF20 LCI	340–360	400 / 580	450 / 650	£599	£325
BMW M240iF22	340–360	400 / 580	450 / 650	£599	£385
BMW 340iF30 LCI	326–360	400 / 580	450 / 650	£599	£325
BMW 440iF32 / F33	326–360	400 / 580	450 / 650	£599	£325
BMW M340iG20 / G21	374	420 / 600	—	£599	£385
BMW 540iG30	340–360	405 / 590	—	£599	£385
BMW 640i GTG32	340–360	400 / 580	450 / 650	£599	£385
BMW 740iG11 / G12	326–360	400 / 580	—	£599	£385
BMW X3 M40iG01	360	400 / 580	450 / 650	£599	£385
BMW X4 M40iG02	354	420 / 580	—	£599	£385
BMW X5 40iG05	340	400 / 580	450 / 650	£599	£385
BMW X7 40iG07	340	400 / 580	—	£599	£325
BMW Z4 M40iG29	340	400 / 580	—	£599	£325

bhp / Nm. Where Stage 2 shows a dash, the supporting hardware isn't commonly fitted to that model — ask us and we'll tell you what's possible. Power Pack cars start higher as standard but land in the same place.

What you're actually buying

Stage 1

£599

Custom map written on the dyno for your car. No hardware needed, around two hours, fully reversible. Most B58s land at 400bhp.

Stage 2

£749

Needs a sports cat or decat and an uprated high-pressure fuel pump. With both on, up to 450bhp and 650Nm.

+ xHP gearbox

£325–£385

The ZF8's shift maps were written for standard torque. Rewriting them is the difference between a fast car and a sharp one. Save £125 booked together.

The B58, briefly

BMW replaced the N55 with the B58 in 2015 — first in the F20 LCI M140i and the F30 LCI 340i, then across almost the whole range. Single twin-scroll turbo, direct injection, and from the B58TÜ revision a closed-deck block that is stronger again. It is the same core engine whether it is sitting in a 140i or an X7, which is why the tuning figures land so consistently. What varies is the gearbox, the exhaust and whether the ECU is locked.

More detail in our B58 buying guide and our write-up on tuning the M140i and M240i.

G-series B58? Your ECU is probably locked.

BMWs built from around June 2020 leave the factory with an encrypted ECU — that catches a lot of M340i, 540i, X3 and X4 M40i, X5 40i and Z4 M40i owners, and it is why some places turn these cars away. It only means the ECU has to be unlocked before it can be written to, and we do that here on the bench rather than posting it off. Drop it in, drive it home the same day.

Check If Yours Is Locked ›

B58 tuning questions

How much power will a Stage 1 remap add to my B58?

It depends which car it is in. A 340i or 440i goes from 326bhp to 400bhp and 450Nm to 580Nm. An M340i goes from 374bhp to 420bhp and 600Nm. A 540i lands at 405bhp. Every figure on this page is measured on our own 4WD dyno, not copied from a file supplier.

Does my B58 need its ECU unlocking first?

If it is a G-series car built from around June 2020 onwards, yes — the ECU is locked from the factory and has to be unlocked before anything can be written. That covers a lot of M340i, 540i, X3 and X4 M40i, X5 40i and Z4 M40i owners. We unlock in-house rather than posting it away, so it is done the same day. Check your registration and we will tell you straight away.

Is Stage 2 worth it on a B58?

Only with the hardware to back it. Stage 2 on a B58 needs a sports cat or decat and an uprated high-pressure fuel pump. The pump is the one people miss — at Stage 2 the limit is fuelling, not airflow, and we will not map it without one. With both fitted a B58 will make up to 450bhp and 650Nm.

What does gearbox tuning add on top?

The ZF8 in your B58 is running shift maps BMW calibrated for standard torque. Once the engine makes more, those maps are the weak link — that is the hesitation before a downshift and the soft change under load. xHP rewrites them: quicker shifts, less lag, firmer engagement and a raised torque limit. It is £325, or £385 on G-series and M cars, and £125 less when booked with your tune.

Is the B58 strong enough to take it?

It is one of the most over-engineered engines BMW have built — a closed-deck block from the B58TÜ onwards, a strong crank and a turbo with genuine headroom. Stage 1 asks nothing of it that it was not designed to handle. We still take a health check before we start, and if something looks wrong we tell you rather than mapping over it.

Will it affect my warranty or insurance?

A remap is a modification, so you need to declare it to your insurer, and it can affect a remaining manufacturer warranty. We save your original file before we touch anything, so the car can go back to standard whenever you need.

Book Your Tune Get a Written Quote Gearbox Tuning Check Another Car

Figures are typical results for a healthy, standard vehicle on our dyno. Your car's actual output depends on its condition, fuel quality and any supporting modifications. Prices shown are for Stage 1 custom dyno tuning inc VAT; locked ECUs carry an additional unlocking charge, confirmed when you book.

420bhp on Stage 1450 on Stage 2