BMW S55 BM3 Tuning Guide – Info & Horsepower Gains

Bootmod3 (bm3) is one of the most popular tunes in the BMW world for good reason. Pro Tuning Freaks bm3 offers a mobile app for simple flash tuning on the BMW S55 engine. They also offer a handful of off-the-shelf (OTS) flash maps with tons of awesome features. Those looking to tune their S55 should definitely consider bm3 flash tunes. In this guide, we discuss S55 bm3 tunes, maps, horsepower gains and more.

Bootmod3 S55 TuningPin

S55 bm3 Flash Tunes Info

Bootmod3 offers off-the-shelf tuning solutions for the S55 M2, M3, and M4 engine. Their OTS tunes are well tested and highly proven on many modern turbo BMW engines, including the S55. Additionally, their flash tunes are easy to install and come in at a solid price point. Here's a quick breakdown of costs:

  • Software license - $595
  • OTS map pack - $50

If you want to run bootmod3 tunes the first step is purchasing the software license. This unlocks the tuning software and allows you to flash a bm3 S55 tune. The license includes one flash tune of your choice. For an extra $50 you have the option to purchase all OTS maps available.

You can likely get by with the 1 tune, but chances are you'll want the flexibility of having multiple tuning options. In other words, you don't need to spend the $50 up-front. However, most people should expect they'll buy the map pack down the road.

Bootmod3 S55 Flash Maps

  • Stage 1. (91 or 93 octane)
  • Stage 2. (91 octane, 93 octane, E30, Racegas)
  • Stage 2H (91 octane, 93 octane, E30, Racegas)

Throughout the rest of this article we'll discuss the above S55 bm3 stages, supporting mods, and power gains for each. Bootmod3 also offers tons of excellent features that we won't dive into much in this article. For more info check out their website, which gives a good overview of S55 M2, M3, and M4 tune features.

*We recommend replacing your S55 spark plugs prior to tuning, especially if they haven't been changed within the last 20,000 miles. The extra power will quickly expose old, weak spark plugs.

S55 OEM Spark Plugs

S55 1-Step Colder NGK 97506 Plugs

OEM BMW S55 Ignition Coils

**Any horsepower numbers are rough estimates. Different dynos and climates, engine health, and tons of other factors may affect actual HP numbers. We're also basing estimates off the supporting mods we recommend. Extra mods, like methanol injection, may result in additional power.

S55 bm3 Stage 1 HP Gains & Mods

Mods Recommended: VRSF Dual Cone Intake

An intake might not offer tons of power on a conservative stage 1 tune. However, it will help the engine breathe a bit better and will still offer some power. It becomes a better mod as more boost and bolt-ons are added. Anyways, S55 dual cone intakes from VRSF are a great price and we love the induction sounds.

Moving on, these bootmod3 stage 1 S55 tunes are the least aggressive option. It's a conservative tune that's a great starting point for those just starting to mod their M2, M3, or M4. No other mods are required, but we do recommend the intake. If not for the small bump in power we think most S55 owners will enjoy the DCI sounds. Otherwise, simply flash the bm3 stage 1 tune and you're on your way.

Bootmod3 Stage 1 HP

91 Octane: 470-485whp / 490-510wtq

93 Octane: 485-500whp / 500-520wtq

A bone stock S55 M3 or M4 will generally dyno somewhere in the 400-420whp and 410-430wtq ballpark. S55 bm3 stage 1 tunes will likely fall in the ballpark of 470-500whp depending on fueling. Pretty impressive gains for a conservative tune and intake only. 91 octane is horrible fueling at this kind of power, so the 93 octane maps are going to add a decent chunk of power.

M2, M3, M4 bm3 Stage 2 HP Gains & Mods

Mods Recommended: VRSF DCI + VRSF Downpipes

Again, an intake will start offering better gains as we get into more aggressive tunes. The biggest difference moving into S55 bm3 stage 2 tunes are the downpipes. It's not a required mod for these tunes. However, the DP's alone are going to help pick up about 15-20whp. Peak power also isn't the only thing. A set of downpipes is going to help turbo spool and improve the top-end power due to better flow.

Exact boost will depend on external factors, but these bm3 stage 2 tunes will generally target about 22-24psi. It's still pretty conservative given plenty have pushed the stock turbos north of 26psi. Without downpipes these tunes won't offer a ton of extra power over the stage 1 tunes, with the exception of the E30 fueling map.

S55 bm3 Stage 2 Horsepower

91 Octane: 485-500whp / 520-540wtq

93 Octane: 500-520whp / 540-560wtq

E30 or Racegas: 510-530whp / 550-570wtq

Expect about 485-530whp on stage 2 S55 bm3 tunes. Those running additional mods like methanol injection can see even more impressive gains. OTS maps are limited to E30 fueling. However, even low E85 mixes offer solid benefits.

These stage 2 bm3 tunes are still relatively conservative. It's basically the stage 1 tune that's optimized for downpipe upgrades. Stage 2H maps up next are actually designed for high-flow turbos. As such, we're going to diverge to custom tuning options for those who want to push the stock turbos further.

S55 bm3 Custom Tuning Options

Mods Recommended: DCI + Downpipes + E85 and/or Methanol Injection

You might even consider some cooling mods since pushing the stock turbos towards their limit will generate lots of heat. The S55 stock fueling system is pretty capable and can handle 100% E85 on 22-24psi. Some may even manage 25+psi on stock turbos and full E85, but it comes down to a case by case basis.

An option is running some methanol injection to help with cooling and fueling. Methanol acts as fueling which will help run 100% E85 at 25-27+psi.

To maximize the power you'll either want to opt for custom tuning or stack a JB4 + S55 bm3 back-end flash. We really like the JB4 + back-end flash setup, but some may prefer the custom tuning route. Regardless, both options can push the S55 to its absolute limit on stock turbos.

JB4 + bm3 or Custom Tuning HP Gains

There are unlimited options if you go this route. You can stick conservative and end up with similar numbers to OTS tunes above. Those who want to push the S55 stock turbos to it's limits will need the proper fueling and methanol to support full E85 on stock fueling. Otherwise, you'll want to consider port injection.

Anyways, the S55 stock turbos can be pushed as far as 600-630+whp and 650-700+wtq. Turbo longevity becomes a question mark at that kind of power and boost. Those with the DCT will be pushing the limits of the S55 clutch packs. It's also a lot of torque for a stock motor to handle for the long-term. Point is - there are risks in taking the S55 this far especially with the small inefficient stock turbos.

S55 Bootmod3 Flash Tunes Summary

BMW S55 M2, M3, and M4 engines from the factory leave a lot of untapped potential. They're built to handle plenty extra, and bm3 flash tunes are a great mod to push the S55 to the next level. Their OTS tunes are easy to purchase and install; they also come loaded with some great features.

Stage 1 S55 bm3 tunes are conservative tunes that don't require any other mods. However, we believe DCI's are a great mod to extract the full potential and free up some awesome sounds. Even the stage 2 tunes are pretty conservative as they're simply optimized for downpipe upgrades on the S55. Again, it's not a required bolt-on mod but it's the only way to extract the full potential of stage 2 tunes.

Those looking to push the stock turbos further should consider a JB4 + bm3 back-end flash stack or custom tuning. With proper fueling the S55 stock turbos can crank out as much as 600+whp and 650+wtq. Nonetheless, BMW S55 M2, M3, and M4 engines are highly capable with a bm3 tune and some basic bolt-on supporting mods.

What experience do you have with the S55? Are you considering the bm3 tunes?

Drop a comment & let us know!

Or check out our 600+whp S55 Guide

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