BMW B58 tuning: stages by generation.

The B58 is the most tuned BMW engine right now, and that is no accident. It sits in so many models that there is a huge market for it, and it has so much built-in headroom that software alone gets you a remarkable amount. This guide covers what is on the table, where the difference between the two generations lies, and what you need.

Where the B58 is fitted

The list is long. At BMW: M140i and M240i in the F series, 340i and 440i, 540i, 640i, 740i, 840i, the G20 M340i, the G42 M240i, the Z4 M40i, the X3 M40i and X4 M40i, and the X5, X6 and X7 in 40i form. The same engine also sits in the Toyota Supra A90 and A91, for which there is a separate bootmod3 licence.

Of the factory outputs, these are solid, taken straight from BMW press releases:

The other versions sit around those figures depending on model and year. If you want the exact number for your car, check your registration document or give us a call.

Two generations, two stories

This is the most important thing to know about B58 tuning, and it often gets skipped. There are two generations, and they respond differently to software.

The first generation sits in the F20 M140i, the F22 M240i and the F30 340i among others. The second, which bootmod3 calls B58-D, arrived in 2020 and sits in the G20 M340i and the X3 M40i and X4 M40i among others. That second generation received a revised cooling system and different injection pressure, among other changes.

For you as an owner that means: the first generation has more room in the highest stages, the second generation delivers slightly more torque at Stage 1. Both sets are listed separately below, because mixing them up produces the wrong expectations.

Stage 1: software only

You flash through the OBD port with the bootmod3 licence for the B58. Bootmod3 quotes:

First generation

• Stage 1 on RON95: up to 18 percent more power and 26 percent more torque
• Stage 1 on RON98: up to 20 percent more power and 26 percent more torque
• Stage 1 on E30: up to 25 percent more power and 30 percent more torque

B58-D, from 2020

• Stage 1 on RON95: up to 18 percent more power and 28 percent more torque
• Stage 1 on RON98: up to 21 percent more power and 30 percent more torque
• Stage 1 on E30: up to 28 percent more power and 34 percent more torque

Look at the torque figures, because that is where the story is. An M340i that gains 30 percent torque feels like a completely different car in daily driving, and you notice that more often than the extra power up top.

These percentages apply to cars without the MPPK package. If your car already has that package, the gain is smaller because your starting point is higher.

Stage 2 and above

First generation

• Stage 2 on RON95: up to 24 percent more power and 32 percent more torque
• Stage 2 on RON98: up to 26 percent more power and 32 percent more torque
• Stage 2 on E30 or race gas: up to 30 percent more power and 35 percent more torque
• Stage 2+ on RON98: up to 43 percent more power and 52 percent more torque
• Stage 2+ on E30: up to 47 percent more power and 68 percent more torque
• Stage 2+ on E50: up to 50 percent more power and 72 percent more torque

B58-D, from 2020

• Stage 2 on RON95: up to 22 percent more power and 33 percent more torque
• Stage 2 on RON98: up to 25 percent more power and 35 percent more torque
• Stage 2 on E30: up to 31 percent more power and 38 percent more torque
• Stage 2 on E50 or race gas: up to 36 percent more power and 40 percent more torque

That 72 percent torque figure at Stage 2+ on E50 is not a typo. It is the sort of number the B58 owes its reputation to, and it shows how much the factory left on the table.

What you need for the higher stages

On the intake side we work with Eventuri. Which one you need depends on your model:

• Carbon intake system for the F series: M140i, M240i, M340i and M440i
• Intake system for the G20, G22 and G26 from build date November 2018, and there is a separate version for cars built before that
• Intake system for the Z4 M40i
• Intake system for the Supra MK5

On the G20 models, pay attention to that November 2018 build date. It is not a detail, the two versions do not fit each other's cars.

For the X3 M40i and X4 M40i there is a separate B58-D version of the intake system. It is not listed online at the moment, so give us a call if that is the one you need.

We do not sell downpipes. You do need those for a full Stage 2, so call us if you want to go that way and we will think along.

Ethanol: where the big numbers are

Look again at the list above. On the first generation, Stage 2+ goes from 43 percent on RON98 to 50 percent on E50. More importantly, torque goes from 52 to 72 percent. Ethanol is more knock resistant than petrol and that is where the room is.

For that you need a flex fuel sensor, so the software knows what is in the tank and adapts without reflashing. There are two kits: the FlexFuel Kit Basic which you fit in the engine bay in about an hour, and the FlexFuel Kit High Flow which is flow optimised and remains the better choice if you load the fuel system to its limit. Both are plug and play and fully reversible.

A practical note: finding E85 in the Netherlands takes planning. Check whether there is a pump on your regular route before you start.

What to watch out for

The engine computer may be locked

If your car has a software level of November 2019 or later, the DME is locked. For cars built before June 2020 we use the DME bench unlock, and for June 2020 and later the DME unlock where the ECU is shipped in. Budget for that step in your planning.

Know which generation you have

It sounds obvious, but in practice this is what goes wrong most often. A G20 M340i from 2019 is not the same as one from 2021, and that applies to the tune and to the intake. If you are unsure, send us your chassis number.

The gearbox

At higher stages you run into the limits of the eight-speed automatic. On a B58 with a lot of torque that is something you want to discuss beforehand, not discover afterwards.

MPPK package

If your car has the M Performance Power Kit, the percentages above do not apply to you. You start higher, so the gain is smaller.

Maintenance

• Oil. With track days or a lot of full-throttle driving, change it earlier than the service schedule says.
• Spark plugs. More boost asks more of the plug, especially on ethanol. Shorter intervals than standard.
• Let it warm up. Wait for oil temperature before full throttle, not coolant temperature.
• Let it cool down. After a hard drive, take it easy for a bit before you shut it off.
• Read along. Datalogging in the bootmod3 app shows you what is happening. Especially on ethanol that is how you check everything is doing what it should.

What you need to get started

Besides the licence, a bootmod3 wifi adapter or an ENET OBD cable, and with software from November 2019 onwards a DME unlock first.

What we do with it

We work with bootmod3 daily in our workshop in Elburg. You can order the licence from us and flash it yourself, or have us do everything: unlock, licence, tune, and the intake and flex fuel kit alongside it if you want. After your order we will contact you to make an appointment.

More background: what Stage 1 tuning actually is and how tuning relates to your warranty, insurance and roadworthiness test.