We’re finally following up on our general MHD post. This guide will go more in-depth on BMW N55 MHD E series flash tunes and expected power gains. All E series N55s use PWG. However, some F series are also PWG rather than EWG. The F series uses a different MHD app, so we will write a separate post for that. Although, PWG F series N55s should expect similar power gains to the E series we are writing about here. If you’re unsure of the differences between EWG & PWG click here. Anyways, let’s jump in and discuss MHD flash tunes for the N55 E series.
N55 E Series MHD Tunes
Feel free to skip ahead if you’re familiar with MHD and flash tunes in general. MHD offers off-the-shelf (OTS) flash tunes for the BMW N55 engine. The purpose of a flash tune is to effectively re-write the DME and target more aggressive boost. A flash tune allows for full control over parameters like ignition advance, fueling, etc. This control is a big benefit of flash tunes when compared to piggyback tunes like the JB4.
Piggybacks act as advanced boost controllers, but do not re-write the DME. The JB4 is able to intercept and alter signals to run more boost and increase fuel flow – just to name a few things. However, it’s limited by the parameters built into the factory DME. Given enough boost and power, the JB4 and factory DME tune will eventually reach a limit.
This is where flash tunes like MHD come into play. MHD offers four “stages” for the E series N55 and a 5th stage for E30 fueling. The four base maps also have different options depending on fueling. MHD’s flash tunes are highly proven and are a go-to option for many N55 E series owners.
N55 JB4 + MHD Back-End Flash (BEF)
We’re diverging for another quick paragraph to discuss one of our favorite off-the-shelf tuning options. Stacking a JB4 piggyback tune with an MHD back-end flash (BEF). We love this setup for multiple different reasons. First, the JB4 comes loaded with unique features. A few of those features include steering wheel controls, gauge hijacking, on-the-fly map changes, and data-logging. The JB4 also offers superior support and control for things like methanol and port injection. Finally, (well not really finally – the JB4 has many other benefits that we’re not even mentioning) Burger Motorsports JB4 offers superior safety features.
When stacking with an MHD back-end flash, the JB4 retains all of its unique features and remains in control of boost targets. However, the back-end flash takes control of fueling, load, ignition advance, etc. It’s the best of both worlds and we highly recommend this setup.
*Note – you will need to purchase the JB4 and MHD software licenses. The actual back-end flash maps are free.
N55 E Series MHD Maps (“Stages”)
As we mentioned briefly, MHD offers four different stages for the N55 along with a 5th stage for E30 fueling. The stages have different supporting mod recommendations. Generally, more aggressive stages require additional supporting mods. Additionally, power and boost increase with the more aggressive stages – assuming all else equal, such as fueling. Available stages for the N55 are 1, 1+, 2, and 2+. Within each of these stages are different options depending on fueling. The E30 map is considered stage 2+. In the remainder of this post we will discuss each of these stages, supporting mod recommendations, and expected horsepower. A few quick notes before we move on:
*We highly recommend replacing spark plugs and ignition coils prior to tuning your N55, especially if this has not been done in the past ~30,000 miles. Tuned and modded N55’s are generally best suited to the NGK 97506 1-step colder spark plugs. However, OEM plugs generally hold up well for most people under ~400whp.
**ALL horsepower numbers we mention throughout the post are assuming the N55 is running the recommended supporting mods for each stage. Also, the horsepower figures should be taken as rough estimates. Power varies from car to car – even with the exact same mods. Some of this comes down to differences in dynos, temperature, engine health, etc.
N55 MHD Stage 1 Horsepower & Mods
Mods Recommended: Intake
Target Boost: 13-15psi peak, tapering to 11-12psi at redline
The MHD N55 stage 1 tune is a pretty basic, entry-level tune. No supporting mods are absolutely required, however, we recommend an upgraded intake to support additional air-flow. It’s unlikely a performance intake will offer big gains on this modest tune. However, in our opinion, an open intake is worth it for the sound alone.
ACN91/93 RON: 290-300whp / 340-350wtq
91 Octane/95 RON: 290-300whp / 340-350wtq
93 Octane/98 RON: 300-310whp / 350-360wtq
95 Octane/102 RON: 300-310whp / 350-360wtq
Bone stock PWG N55s normally dyno in the ballpark of 270whp and 285wtq. As you can see, the bump in power isn’t that drastic. Stage 1 MHD N55 tunes will make somewhere in the ballpark of 290-310 wheel horsepower and 340-360 torque. ACN (AZ, CA, NV) 91 octane is poor fueling so you may not even break 300whp on these modest stage 1 tunes. While “normal” 91 octane is better than ACN91, it’s still not great fueling. Expect boost targets around 13-13.5psi and power around 300whp. 93+ octane fuel should result in slightly more aggressive boost targets and will help pick up a few extra horsepower.
*You’ll notice as we move through the MHD stages that the N55 E series PWG turbos really struggle on the top end. As such, torque gains will look fairly impressive despite underwhelming power. The tiny PWG turbo simply cannot flow enough air on the top end. Torque drops off aggressively around 4,500 RPM’s which really limits the peak horsepower gains.
N55 MHD Stage 1+ Horsepower & Mods
Mods Recommended: Intake + FMIC
Target Boost: 13-15psi peak, tapering to 11-12psi
N55 stage 1+ maps are not too different from the standard stage 1 maps. Boost targets remain roughly the same. You may target slightly more aggressive boost, like .5psi. However, it’s still a slightly more aggressive tune. Rather than relying on more boost the stage 1+ maps rely on more aggressive tuning to pick up some extra power. As such, we recommend an upgraded FMIC. This will help keep IATs in check and allow the tune to target its slightly more aggressive parameters.
ACN91/93 RON: 300-310whp / 350-360wtq
91 Octane/95 RON: 300-310whp / 350-360wtq
93 Octane/98 RON: 310-320whp / 360-370wtq
95 Octane/102 RON: 310-320whp / 360-370wtq
N55 MHD stage 1+ wheel horsepower comes in around 300-320whp. Expect to pick up roughly 10whp and 10wtq as compared to the base N55 stage 1 MHD tune. Again, lower-grade fuels will result in lower boost targets and less power (assuming all else is constant). Upgraded intercoolers generally don’t pick up any peak power on glory runs. However, a notable difference lies in the consistency. Without an upgraded intercooler you will notice the tune pulling back boost and timing on back-to-back runs when IATs spike too high.
N55 MHD Stage 2 Horsepower & Mods
Target Boost: 14-18psi peak, tapering to 11-12psi
The N55 MHD stage 2 tune is starting to get a decent bit more aggressive. Boost targets move up to 14-18psi. However, notice the PSI on the top-end still tapers down to roughly the same as the stage 1 tunes? That’s because the tiny stock turbo simply can’t move enough air up top. The higher boost targets are going to make some more impressive torque on the low-end and mid-range. That will also be magnified with the addition of an N55 catless downpipe. We think this is a great mod no matter what tune you opt for. The butt-dyno will approve thanks to quicker turbo spool. However, the torque gains will also be notable on the dyno.
ACN91/93 RON: 310-320whp / 360-370wtq
91 Octane/95 RON: 315-325whp / 370-385wtq
93 Octane/98 RON: 320-330whp / 390-405wtq
95 Octane/102 RON: 330-340whp / 400-415wtq
You can generally expect around 310-340whp from the N55 MHD stage 2 tune. Boost targets are beginning to become aggressive enough to the point ACN91 falls behind normal 91 octane. With all of the recommended supporting mods on 93+ octane boost targets will likely run up to the ballpark of 16-17psi. Given the additional boost, peak torque gains are pretty impressive as compared to the previous stages.
N55 MHD Stage 2+ Horsepower & Mods
Target Boost: 14-18psi peak, tapering to 11-12psi
Like with the MHD stage 1 vs 1+, boost does not change much on the N55 stage 2+ MHD tune. Again, you may pick up an extra .5 to 1psi in the mid-range. However, the stage 2+ will mostly target slightly more aggressive parameters to pick up a few horsepower. Supporting mods remain the same.
ACN91/93 RON: 315-325whp / 370-380wtq
91 Octane/95 RON: 325-335whp / 380-400wtq
93 Octane/98 RON: 330-340whp / 400-420wtq
95 Octane/102 RON: 340-350whp / 410-430wtq
N55 horsepower with the MHD stage 2+ tunes comes in at roughly 315-350whp. The power gains are nothing crazy when compared to some other modern turbo BMW engines. Unfortunately, the PWG N55 just has an inferior torque curve which limits the peak power gains. Nonetheless, the torque gains remain impressive and definitely add a lot more fun in the mid-range.
N55 MHD Stage 2+ E30 Horsepower & Mods
Target Boost: 19psi peak, tapering to 13psi
The N55 MHD E30 fueling tune (considered a stage 2+ tune, also) is going to be the most aggressive OTS tuning option from MHD. Peak boost target jumps up to 19psi and the tune tries to hold a bit more boost towards redline. Once again, we recommend being full bolt-on.
E30 Fuel: 360-375whp / 450-470wtq
These numbers may be a bit on the aggressive side, especially the upper end of the range we listed. However, that’s really about as much power as an E series PWG N55 can make. Sure, with custom tuning options, more E85, meth injection, etc you may be able to stretch things a bit further. Some PWG N55s have eclipsed 400whp, but it’s not terribly common.
N55 E Series MHD Flash Tunes Summary
MHD offers some excellent OTS tuning options for the N55 E series. Expected power with MHD tunes comes in the ballpark of ~290whp on conservative stage 1 tunes with poor fueling, up to ~375whp with the most aggressive E30 tune. Torque gains prove to be much more impressive than power gains alone. This is no fault of MHD; they really are great OTS options. However, the tiny PWG N55 turbo struggles to move enough volume on the top end. This results in rather underwhelming power gains when compared to some of the other modern turbo BMWs.
Nonetheless, these MHD tunes will certainly add quite a bit of life to your N55. For those looking to push the limits further, consider opting for a custom MHD tune or stacking the JB4 and MHD back-end flash tunes. Though, if your end goal is 400+whp you may want to simply jump straight into an upgraded turbo.