Following our general MHD post, we will now go more in-depth on B58 MHD tunes and expected power gains. Scroll down a bit if you're only interested in the power gains. Otherwise, let's quickly discuss some basic MHD B58 tuning concepts.
About B58 MHD Flash Tunes
MHD offers OTS (off the shelf) flash tunes for the B58 engine. OTS tunes from MHD are extensively tested and highly proven in the BMW tuning world. Additionally, B58 MHD tunes are easy to install and affordable. A quick breakdown of MHD costs for B58:
- Flasher Module - $249 (required)
- Map Packs - $99 each (two available, only one required)
- Monitor Module - $99 (optional, but highly recommended unless stacking with JB4)
All in, you're looking at $546 for the flasher module, both stage 1 and 2 map packs, and the flasher module. We recommend starting with only 1 map pack and getting the 2nd later on, if needed. However, we strongly advise spending the $99 on the monitor module. This allows data-logging capabilities so you can monitor your engines operation. Once tuned, it's never a bad idea to data-log frequently to keep an eye on engine performance. The JB4 offers free data-logging features, so disregard the MHD option if you're looking to stack a JB4 and MHD back-end flash. More on this in the next couple paragraphs.
B58 Flash vs Piggyback Tunes
B58 flash tunes, such as MHD, re-write the factory DME programming. Essentially, flash tunes gain complete control of all engine tuning parameters. This includes boost, fueling, timing, and load - just to name a few. Ultimately, the goal of a B58 flash tune is to increase turbo boost pressure. The flash tune is then also programmed to account for the additional fuel flow required, any necessary timing adjustments, etc. To summarize, flash tunes allow for excellent precision and tuning capabilities.
Piggyback tunes for the B58, such as JB4's, take a different approach. These tunes basically function as advanced boost controllers. They do NOT rewrite the DME. A JB4 essentially sets the boost target and lets the factory DME tune make the necessary adjustments. However, the DME never sees the true boost target the JB4 is setting. Some people knock piggyback tunes since they "trick" the DME. Though, we love the JB4. It's easy to install, comes loaded with features, and is a great overall tune. Piggyback tunes function as advanced boost controllers, but they are limited by the factory DME tune.
B58 JB4 + MHD Back-End Flash
For ultimate B58 tuning, we recommend stacking the JB4 and an MHD back-end flash tune. The B58 JB4 comes with, in our opinion, superior features and better boost control. It also allows for on-the-fly map changes in just seconds. No need to completely re-flash the DME. However, the JB4 is limited by factory tuning variables. Enter the B58 MHD back-end flash. The flash tune re-writes the factory DME allowing for precise, aggressive tuning. With this route, you will not need the MHD monitor module or any map packs. Simply purchase the JB4 and MHD flasher module and the actual flash maps are free.
Beware though. Stacking these tunes can be pretty aggressive on stock turbo B58's. With proper supporting mods, a JB4 and MHD back-end flash have the ability to nearly max the stock turbo. The back-end flash maps can run up to 50% E85. Again, beware. This tune combination is plenty aggressive to max the B58 fueling with too much E85.
B58 MHD Stages & Maps
As discussed briefly above, MHD offers two stages for the B58 engine. Within each stage there are multiple maps for different fueling. We'll discuss the two stages and different fuel maps throughout the remainder of the post. This will include estimated power on each stage and fuel.
*We highly recommend replacing B58 spark plugs prior to flashing MHD tunes, especially if the spark plugs are 25,000+ miles old. Ignition coils may also be a good idea for those with 50,000+ miles.
**Horsepower figures are estimates. They also assume you are running all recommended mods. Additional mods that we do not mention may result in extra power, such as meth injection. Furthermore, power may vary from car to car even with the exact same mods. Some differences come down to dynos, temperature, altitude, engine health, etc. Even when all things are equal some natural variance is normal.
B58 MHD Stage 1 HP Gains & Mods
Mods Recommended: Intake
First off, performance intake power gains are questionable. The B58 factory airbox is pretty efficient as is. Intakes really only add power if the stock intake is struggling to keep up with air flow demand. Stage 1 MHD tunes likely are not aggressive enough for this to be an issue. Nonetheless, if not for the small potential power gains, we recommend an open intake for the sound alone.
With that said, MHD stage 1 tunes are the least aggressive MHD offering for the B58. No mods are absolutely required. Simply flash the DME and go.
MHD Stage 1 HP
91 octane/95 RON: 360-370whp
93 octane/98 RON: 370-380whp
95 octane/102 RON: 380-390whp
Expect hp figures in the 360-400whp ballpark on stage 1 MHD tunes with an upgraded intake. As suggested, power increases with fuel quality. 91 octane is poor fueling and only recommended if you do not have access to better fuel. If E85 is available, we highly recommend mixing 20-30%. Power approaching 400whp on a pretty conservative tune is impressive to say the least.
B58 MHD Stage 2 HP Gains & Mods
Mods Recommended: Catless DP + Intake
Stage 2 B58 tunes provide a respectable bump above stage 1 performance. It is highly recommended to install a catless downpipe or high flow catted downpipe prior to stage 2 MHD tunes. A catless downpipe will provide a nice bump in power by itself. Additionally, catless downpipes reduce turbo lag and help the B58 hold more boost up top. The butt-dyno will definitely approve of this mod thanks to the lightning quick spool.
MHD Stage 2 HP
91 octane/95 RON: 380-390whp
93 octane/98 RON: 390-400whp
95 octane/102 RON: 400-410whp
B58 MHD stage 2 figures come in around 380-430whp. Nothing to snarl at for a few basic bolt-ons and a flash tune. Again, we advise running an E85 mix if available. You may even consider running meth injection to pick up a bit of extra power.
B58 JB4 + MHD BEF HP Gains & Mods
Mods Recommended: Catless DP + Intake + WMI
We're throwing meth injection into the list of recommended mods here. You can absolutely run this setup with no other mods. Also, regardless of mods, we believe this is a great setup for anyone. However, the goal here is to showcase the capabilities for those looking to push the B58 stock turbo limits.
B58 JB4 + MHD HP
91 octane/95 RON: 400-430whp
93 octane/98 RON: 410-440whp
95 octane/102 RON: 420-450whp
E85 map w/ E40 mix: 450-480+whp
These are pretty aggressive power assumptions here. We also provided a rather large range since power will be highly dependent upon many factors. There are several different back-end flash maps. Additionally, you can then select a map on the JB4. Basically, there are is a wide variety of options to choose from to dial in the tune and boost to your goals. Meth injection will assist in reducing overall fuel demand. However, on E40 fueling be sure you're data-logging and keeping an eye on fuel flow. Ensure you're not leaning out.
BMS (JB4) pushed a B58, with only E40 fuel and an intake, to 460whp on 19 pounds of boost. They were running AFR's as lean as they felt comfortable. This highlights the fact that fueling becomes a concern at this kind of power. Again, meth should help. Nonetheless, this is incredible power for stock turbo B58's. We're impressed the B58 has accomplished so much already. Look no further than the JB4 and MHD combo to push things towards the limit.
B58 MHD Flash Tunes Summary
The B58 has already proven to be one heck of an impressive performance engine. Conservative stage 1 MHD tunes are able to push the B58 into the 400whp ballpark with some E85 to help. Stage 2 tunes take things up a notch with expected power in the 380-430whp range. These are both excellent tuning options for the B58 and you cannot go wrong.
However, we ultimately recommend stacking a JB4 with an MHD back-end flash. We truly believe this is the best tuning solution on the market. Things can get aggressive quickly, though. You can, of course, stack this tunes and opt for a conservative tune. The JB4 also offers on-the-fly map changes so you can switch from a conservative daily driver tune to kill mode in seconds. Push things too far on this setup and you may quickly find the stock turbo and stock fueling limitations.