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The BMW 340i has the B58B30: a 3.0 litre twin-scroll turbocharged straight-six making 326PS (322bhp) and 450Nm as standard. It arrived with the F30 LCI in 2015 and replaced the N55 that powered the 335i, bringing a closed-deck block, higher compression and an intercooler built into the charge air housing. That is also why it takes tuning so well: on our dyno a Stage 1 file takes a standard 340i to around 400PS and 580Nm on software alone.
Measured on our Mustang AWD rolling road in Maidstone. Wheel figures, drivetrain loss added for the flywheel numbers.BMW 340 ECU Remapping gives staggering results, even we are impressed.
BMW 340i Stock Figures
The 3.0l petrol engine in the 3roi has some very impressive figures out of the factory. BMW says it produces 326BHP and 450Nm torque. That’s pretty quick for a car that you can buy in an estate shape! We put the car on the dyno and carried out some stock runs so that we had a baseline to compare our stage 1 software against. We found that this car in particular was actually running 346BHP and 475Nm torque! German car manufacturers generally understate their power figures when releasing a new model so we expected a small increase like this.
We spent around 15 hours on the dyno recording in depth data logs of the engine and gearbox to get a true understanding of how its runs from factory and what is possibilities are.
BMW 340i Tuning Figures
We spent a couple of hours analysing the hundreds of maps within the ECU to make the perfect tune. After some calculated map changes and magic from our tech guys, the car is producing 424BHP and 643Nm torque! We transformed this nippy 340i to a real competitor to cars like the Golf R. The benefits don’t stop there though as the dyno graph shows; both power and torque delivery is much smoother now making for a much better ride all the time, whether you’re driving 30 or 70mph.
BMW 340i Tuning Module Development
Some drivers don’t want a direct map to the ECU for many reasons, mainly warranty or insurance. We have developed our plug & play tuning module system to work with the BMW 340i engine, which means we no longer need to remove and disassemble the ECU.
Our tuning modules are a great way to tune your engine, which is non-intrusive and should you wish to, is able to be returned back to stock within a matter of minutes.
Our module system uses multi channel technology to plug into multiple engine sensors allowing it to control turbo boost levels, fuelling and throttle valve control.
After some stock dyno runs we found the 340i engine produced 346BHP & 475Nm from factory, 24BHP & 25Nm over BMW’s quoted figures.
The JFA Tuning Module kit took power output to an impressive 425BHP and 560Nm Torque!
We data logged boost pressure, ignition timing and fuelling to be sure the engine was running 100% safe.
BMW 340 ECU Remapping is only a snippet doe the services we have to offer here at JF Automotive. We also have a range of other services for BWM and all makes and models.
Photos from the build
5 photos of this BMW in our Maidstone workshop. Tap any to enlarge.
Questions we get asked
What engine does a BMW 340i have?
A B58B30. It is BMW's 3.0 litre twin-scroll turbocharged straight-six petrol, rated at 326PS (322bhp) and 450Nm in the 340i. Every 340i built from 2015 uses it, including the F30 saloon, F31 Touring and F34 Gran Turismo.
Is the 340i engine the same as the 335i?
No. The 335i used the N55 (and the earlier E90 cars the N54), both 306PS. The 340i replaced it in 2015 with the all-new B58: a closed-deck block instead of an open deck, higher compression, more boost and the intercooler integrated into the charge air housing. It is a stronger and more tunable engine than the one it replaced.
How much power does a 340i make?
326PS and 450Nm as standard, which is 322bhp in old money. North American cars are quoted 320hp and 330lb-ft because they are measured to a different standard; it is the same engine.
How much power does a remapped 340i make?
A Stage 1 remap takes it to around 400PS and 580Nm on our rolling road, with no hardware changes and the standard turbo, exhaust and catalyst retained. That is roughly +74PS and +130Nm, and the mid-range change is bigger than the peak suggests.
Which BMWs use the B58?
It is used widely across the range: the 340i and later M340i, the 440i, 540i, 640i, X3 M40i, X4 M40i, X5 40i, Z4 M40i and the Toyota Supra A90. The tuning approach is the same for all of them, though the state of tune and the gearbox differ.
Is the B58 reliable?
It has a good reputation and is generally regarded as the stronger of the two, being a closed-deck design. Keep on top of the oil service intervals with the right specification oil, and watch for the usual charge pipe and cooling system items as the miles build. A properly written remap does not shorten its life; chasing a number well past what the standard hardware supports will.
Do I need to tune the gearbox as well?
Not for Stage 1. The 340i uses the ZF 8HP automatic, which has its own torque limiter. If you go further than Stage 1 it is worth tuning the gearbox at the same time so the limiter does not clip what the engine is making, and you get faster shifts and a manual mode that holds a gear.
What years is the BMW 340i?
2015 to 2019 in the F30 saloon and F31 Touring, and 2016 on in the F34 Gran Turismo. From the G20 generation in 2019 the badge became M340i, with the same B58 in a higher state of tune at 374PS.
