2021 BMW 840i (G16) - Locked ECU Dyno Test - B58 340hp Performance Tuning

In our latest dyno test we had this awesome 2021 BMW 840i in for tuning and dyno testing. We’ve already conducted extensive development on these, so already know what the 3.0 B58 is capable of. After a quick installation of our 3 channel module, it was up on the rollers to see what gains had been made.

This G15 is also another example of a 2021+ BMW facing the tuning limitations due to the locked ECU, and currently has no way to read or write the ECU data. This means that while traditional remapping is impossible, our tuning box can give owners the opportunity to make fantastic gains without requiring a traditional ECU flash. This has the added benefit of being traceless once removed for warranty purposes.

Dyno testing before and after shows healthy gains across the rev range, with a significant increase in power and torque, really transforming how it feels to drive.

Peak power was significantly increased, as we were able to lift it from 358hp at stock, up to 431hp with the box. If you take a look at the dyno graph below you can see how we change that curve (dotted red and blue lines). We give real consistency here, bringing that extra power in as soon as possible, whilst holding it for as long as possible throughout the entire rev range, adding that +73hp at its peak, really transforming how it feels out on the road.

Torque also saw some really impressive improvements. At stock the engine produced 564Nm and now 722Nm with the box. If you take another look at the graph (solid lines), you can really see where we have applied those gains. Again looking across that whole portion of the mid-range, you can really see exactly where its lifted, adding the +158Nm extra at its peak, delivering that increase exactly where it’s needed.

Check out the full dyno test here: