BMW B58 Water Methanol Injection (WMI) Guide

Water methanol injection is common subject in the BMW tuning world. We touch on WMI in several other B58 posts, but it's time to finally tackle the topic in full. Methanol injection comes with a handful of benefits, but it's not without risk. In this guide, we discuss the benefits, risks, and power gains of B58 WMI kits. We also touch on a few of our favorite kits on the market for the B58.

B58 BMS Meth Injection KitPin

*BMS B58 WMI Kit pictured above

B58 Water Methanol Injection Benefits

Benefits of running a B58 methanol injection kit include:

  • Power gains
  • Cooling benefits
  • Knock suppression
  • Acts as additional fueling

Many choose to run WMI for its performance and power benefits. Methanol injection horsepower gains on the B58 can vary from roughly 20whp up to 100+whp. A lot depends on mods and tuning goals. With a conservative tune on the stock turbo the B58 may only pick up 20whp. On the other hand, aggressive tuning with an upgraded turbo may show gains in excess of 100whp.

However, the benefits of WMI extend beyond just the power gains. Water methanol injection helps cool intake and internal engine temperatures. This in part helps reduce the chance of engine knocks. Additionally, methanol acts as fueling which means fuel demands from gasoline and E85 are reduced. The benefits of B58 WMI are actually very similar to E85. However, E85 increases demand on the fuel system while methanol injection decreases demand.

B58 E85 vs WMI

E85 is our personal preference for those looking to make 500+whp. We believe WMI is somewhat of a band-aid for horsepower and fueling. That's not to say methanol injection is bad. The B58 loves octane and is handicapped without it. However, not everyone has easy access to E85 and/or high octane race gas. Enter B58 WMI. Methanol is considered a high octane fuel hence all of the benefits it provides.

Even those who have easy access to E85 or race gas may still find benefits in running WMI. There's no reason you can't run water methanol injection and E85 together. We actually really like the thought of this setup. However, in this case we would recommend relying on the E85 as fueling and actually running 100% water injection. You'll have the benefits of cooling the intake charge with water injection, but let the E85 act as the sole fueling.

B58 WMI Risks

It's important to note - methanol injections risks can be mitigated with a proper setup and fail-safes in place. Let's highlight a few of the risks and discuss methods to minimize said risks:

  • Loss of methanol flow
  • Uneven methanol flow
  • Highly flammable

We'll discuss the first two points just below. The third is pretty straight-forward. Methanol is highly flammable so you want to be cautious of where and how you setup the kit.

Loss of B58 WMI Flow

B58 WMI kits rely on a pump to flow the mix from the tank to the nozzles. Should that pump fail then the cylinders may be starved of the water methanol mix. There are also rare cases of hiccups or clogged methanol nozzles. You may also forget to re-fill the methanol tank and run it dry. Remember, methanol acts as fueling. If flow cuts off you may end up in a situation where the engine (or specific cylinders) are running lean. That's a recipe for engine knocks. If you're pushing the B58 hard, heavily relying on methanol injection, and end up in lean situations the possibility of engine damage is very real.

Mitigate this risk with a proper setup with fail-safe systems in place. We highly recommend integrating B58 methanol injection kits with the JB4. The JB4 will quickly pick up on the loss of WMI flow and pull boost to avoid knocks and potential damage. There are other fail-safe and integration methods, but we don't have time to cover everything. We truly believe JB4 methanol integration is the simplest and most effective method.

Uneven Methanol Flow

This is similar to the above issue. However, uneven meth flow affects individual cylinders rather than a complete loss of flow. Most B58 WMI kits inject methanol into the charge pipe. As the water methanol mix travels through the charge pipe and intake manifold it's possible for some cylinders to lose flow. Cylinders 1 and 6 are the primary concern as they lie at the far ends of the manifold. As with the above, if you're heavily relying on methanol as a band-aid to fueling then uneven flow may lead to serious damage.

Direct port methanol injection helps mitigate this risk. Direct port kits inject the water/methanol mix directly into each of the 6 intake ports. This allows each cylinder to receive precise, uniform flow. Of course, this is assuming the meth nozzles/solenoids/injectors don't fail. However, it's extremely rare. You still want proper integration and fail-safes even with direct port methanol.

What is the Best B58 WMI Mix?

A 50/50 mix is a good option for the B58. We recommend going no higher than 50% methanol. However, anything from 50/50 all the way to 100% water are good options. The M4 GTS actually uses 100% water injection. Without methanol you lose out on the fueling aspect. However, water is excellent at absorbing heat, cooling intake and internal temps, and acting as knock suppression.

Methanol is considered a high octane fuel. As such, the methanol aspect of the mix is generally sought after for bigger performance gains. Stick to 30-50% methanol and 50-70% water.

B58 Charge Pipe WMI vs Direct Port WMI

Charge pipe (CP) WMI injection is generally cheaper. It's also proven to be an effective option, so CP injection is commonly used. However, charge pipe methanol injection may starve certain cylinders due to uneven flow. That's not to say we're against CP methanol. It's a great option for those running conservative setups and/or running an E85 mix.

Those pushing the B58 to 500+whp on pump gas alone should definitely consider direct port methanol solutions. At this point, the methanol is acting as a band-aid for poor primary fueling. You're heavily relying on the methanol to act as high octane fuel and knock suppression. It's important to ensure all cylinders are receiving equal flow, and injecting meth straight into the B58's intake ports is the best way to accomplish that. Port WMI is more expensive, but it's the superior system from a performance and safety standpoint.

Best B58 Water Methanol Injection Kits

Now that the background information is out of the way let's discuss some of our favorite options on the market. We kept this pretty short and skipped over plenty of great solutions out there. You may consider looking into WMI kits from Snow Performance, AEM, etc. Additionally, we highly recommend the JB4 tune for its simple WMI integration and superior safety features.

1) B58 WMI BMS Kit

Burger Motorsports, creators of the successful JB4, offers an excellent CP WMI injection kit for the B58. Starting at $419 for the full kit it's well priced, too. There are options to go for larger methanol tanks, dual nozzles, billet cap, and a billet nozzle mount adaptor. The fully optioned kit can run up to $776. It's also setup to integrate with the JB4, a tune we highly recommend regardless. However, it's another expense to consider for those not already running a JB4.

The B58 BMS kit is highly proven, well priced, and offers excellent safety features. JB4 integration allows for extremely precise control over methanol flow. The pump flow signal is also sent to the JB4 for increased safety. The JB4 will quickly pick up on a lack of flow and pull boost to avoid potentially dangerous lean situations before they happen.

For a charge pipe methanol injection kit, the B58 BMS option is by far our favorite. It's a proven kit for a good price from a well-known company that's long been building great B58 aftermarket parts.

Price: $419 - $776

Buy Here: B58 BMS Water-Methanol Injection Kit

2) ProMeth Direct Port Methanol Injection Kit

This is a little bit premature as this kit hasn't even officially hit the market yet. ProMeth makes direct port methanol kits for the N54 and N55 and they are currently working on releasing a kit for the B58. We trust it will be a highly successful kit capable of powering some seriously powerful B58's. Again, port WMI is the way to go if you're planning to heavily rely on meth at 500+whp.

Otherwise, we don't have too much information. Rather than regurgitating the basics, check out this brief forum post that lays out some of the basics of the ProMeth B58 kit. If you're interested in this kit we recommend contacting ProMeth. They may be looking for testers or at least have a timeline as to when kits will be available.

Price: Unknown

Buy Here: Unknown

*We'll update the above info once more information is readily available for this kit.

BMW B58 Water-Methanol Injection Summary

WMI offers many benefits for the B58 engine, and most will be enticed by the impressive power gains. Benefits of methanol are similar to those of E85 or high octane race fuels. Though, unlike E85, methanol actually reduces demand on the fuel system. WMI does come with a few risks that should be considered. Ultimately, many risks can be mitigated with a proper setup and tuning, good integration, and fail-safes.

Charge pipe injection is a popular option as it's proven and cost friendly. However, it's a bit less precise than direct port methanol due to the potential of uneven flow. We like the charge pipe injection for modest setups that aren't relying on methanol too heavily. Our favorite option is the BMS B58 WMI kit as the JB4 integration allows for simple setup, precise control, and safety features.

Those looking to push things hard on pump gas and methanol injection should consider port injected options. Options are currently limited, but ProMeth is developing a kit that looks enticing. Twisted Tuning may also be in the process of developing a port methanol solution.

Do you run WMI on your B58? What kit or setup are you considering? Leave a comment and let us know!

Or check out our 500hp B58 guide

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