BMW N55 WMI – N55 Water Methanol Injection Guide
Zach is a BMW enthusiast with a passion for performance. With over 10 years of experience modifying and performing DIY work on BMWs, he’s developed a deep understanding of virtually every BMW engine. He’s also the proud owner of a 600whp N54 with upgraded twin turbos and an E30 325i drift car and has a particular affinity for the S58 engine. Zach is highly knowledgeable about all things BMW, but his expertise in tuning and performance mods sets him apart. His experience as an enthusiast, combined with his technical knowledge, makes him an essential resource for anyone looking to improve the performance of their BMW.
We finally wrote some methanol injection guides for the N54 and B58 engines a couple of months back. Now it’s time to show the N55 some love and discuss water-methanol injection. It’s an excellent source of fueling for the N55, and also helps the engine run cooler. There are, however, some risks to running meth injection. In this article, we discuss the benefits, risks, and power gains of N55 WMI kits. We also list a few of the best N55 meth injection kits around.
*BMS N55 WMI Kit pictured above
BMW N55 Meth Injection Benefits
Some benefits to running water methanol injection on the N55 engine include:
- Horsepower gains
- Cooler temps
- Knock suppression
- WMI acts as fueling
- Some intake valve cleaning
Of course, one of the main reasons people opt for N55 WMI kits is for the horsepower gains. Exact power gains depend on many factors like turbo setup and tuning. How heavily you want to lean on methanol injection also plays a role. More on this throughout the post. However, stock turbo N55 engines usually see gains of 20-40whp on methanol injection. You may even see a power increase of 50-100+whp with an upgraded turbo while heavily leaning on methanol.
Anyways, the way in which WMI makes more power is several fold. For one, injecting the water methanol mix drastically cools the charge air and reduces the chance of engine knocks. N55 meth injection also acts as additional fueling further helping prevent knocking. Lastly, WMI flowing through the intake ports may assist in limiting carbon deposits. There’s not enough flow to fully prevent carbon build-up, but it does help slow the process on the BMW N55 engine.
N55 WMI or E85 Fuel?
BMW N55s love high-octane fuel and the engine is handicapped without it. Therein lies the problem. Not everyone has easy access to E85 or higher octane racing fuels. Methanol is actually a high-octane fuel. It’s highly flammable and easy to ignite. Hence part of the reason it’s usually used as a mix, with about 50% methanol and 50% water. We’ll circle back to this topic in a few moments.
Those with access to E85 and/or high-octane fuels can still couple all of those fueling solutions with methanol injection. We actually believe an E85 mix with WMI is a great overall setup. We believe it’s the ultimate solution to N55 fueling, cooling, power, and knock suppression. That said – if it’s one or the other – we prefer running E85 to methanol injection. Even then, WMI acting as fueling does offer tons of benefits since E85 can quickly max the stock N55 fuel system.
N55 WMI Risks
As we’ve hinted a few times, there are a few risks to running water meth injection on the N55. However, there are always ways to mitigate those risks and have a safe, reliable WMI setup. We’ll discuss the following risks and ways they can be reduced:
- Loss of methanol flow
- Uneven WMI flow
- Highly flammable
1) Loss of Methanol Flow
WMI kits use a pump to move the water-methanol mix from the tank to the injectors. If the pump fails then the cylinders won’t receive sufficient methanol flow. Those relying heavily on meth for fueling and knock prevention could do serious damage to the engine, in this case. There are also other things that may lead to a loss or reduction in meth flow. Point is – there is a risk that something in the WMI kit fails.
The best way to reduce this risk is to use a quality fail-safe system. One common option is integrating N55 WMI kits with the JB4 tune. The JB4 tune will quickly notice the lack of meth flow and pull boost to prevent possible damage. This is just one example of fail-safe methods, and a few other options exist that we don’t have the time to cover. Regardless, WMI integration with the JB4 is a pretty simple and effective option.
2) N55 Uneven WMI Flow
Uneven water/methanol flow is similar to the above in the sense a specific cylinder(s) is starved of the WMI mix. This is mostly a concern for those using charge pipe injection kits. On the N55, cylinders 1 and 6 are known to naturally receive a little less flow than the other cylinders. It’s not a major concern for those sticking with modest WMI uses on the N55. This is mostly targeted to those who intend to run pump fuels and push high power with only water-methanol injection as fueling.
If you’re planning on heavily leaning on methanol for power and fueling then you should opt for a direct port methanol kit. We’ll discuss charge pipe vs port meth injection shortly. Anyways, the basic idea is that port methanol injects the mix directly into the intake ports. This ensures all cylinders receive equal flow. Of course, the injectors can fail but it’s very rare and that’s why it’s important to still have proper fail-safes in place.
3) Methanol Is Flammable
Well, this is pretty straightforward. Methanol is highly flammable. Opt for a quality methanol tank and mount it in the trunk. Otherwise, just be cautious of how and where you’re storing methanol.
What is the Best WMI Mix?
50% methanol and 50% water is a common choice. We also think that’s a good choice for those wanting to maximize power. 50% methanol is also probably the highest mix we would be comfortable with. There are even benefits to running 100% water injection on the N55. Water will help absorb heat, cool temps, and act as a knock suppressant.
Methanol is combustible, which is what makes it act as additional fueling for the N55. Again, it also has a high octane rating. If you just want cooling and safety benefits then a heavy water mix is great. Those looking for the most out of their WMI kit will likely want to run 30-50% methanol.
N55 CP WMI vs Direct Port Methanol
Charge pipe methanol injection is the cheapest option for the BMW N55 engine. These kits utilize one or two injectors and spray the water-methanol mix into the charge pipe. As mentioned previously, this may cause uneven flow of methanol but it’s a moot point for most who don’t plan on relying on meth too much. Therefore, N55 CP WMI kits are a great choice for modest setups.
Direct port WMI can be quite a bit more expensive than the CP options. It’s also not the best choice for those who might upgrade to port fuel injection for heavy E85 mixtures. However, direct port methanol offers greater capacity and safety for the N55. Direct port WMI is definitely the way to go if you’re planning to run pump gas and push the N55 to 500+whp. If you are looking for some additional BMW N55 fueling guidance, check out our BMW N55 Fueling Mods Guide.
Best BMW N55 WMI Kits
Alright, we’re finally here. The discussion above was a bit longer since there’s a lot that goes into WMI kits. They offer tons of benefits, but also come with a few risks. Below we’ll be discussing a few of the WMI kits we believe offer the best balance of price, quality, performance, and safety. This is by no means an exhaustive list and tons of great water-methanol injection kits are around for the N55.
1) N55 Burger Tuning WMI Kit
Burger Motorsports – creators of the well-known JB4 tunes – offers a charge pipe WMI kit for the N55 engine. It’s a well-priced kit starting at $419 with a 1-gallon water methanol tank. You can upgrade from there and go with a dual nozzle, 2-gallon tank, and billet cap with a safety check valve. All of the upgrades together bring the full WMI kit up to $677. We highly recommend going for a dual nozzle setup and upgrading to the billet cap. The 2-gallon tank is a nice upgrade, but at $179 some may understandably find it excessive.
Anyways, the BMS N55 WMI kit is a highly proven option that offers great quality for the price. The one catch is that it relies on the JB4 for integration. We love the JB4 and think it’s a great tune to stack with a back-end flash tune. If you don’t already have a JB4 it’s another expense to consider, though. We still like the option since the JB4 integration is simple and offers solid safety features.
Price: $419 – $677
Buy Here: N55 BMS Water-Methanol Injection Kit
2) Fuel-it! N55 Direct Port Meth Injection Kits
We’ve talked about fuel-it often regarding their awesome fueling solutions for many BMW engines. They make some great products, and we really like their N55 direct port methanol kits. These WMI kits also offer some choices so you can get the right setup for your specific N55. The base kit comes with six 550cc injectors, which you can upgrade to 750 or 950cc. They also offer JB4, Split Second AIC6 with JB4, and Split Second AIC6 for flash tune only integration.
Fuel-it direct port WMI kits certainly offer plenty of flow with the injector options and the integration options are perfect. There’s something for everyone with this N55 kit. The catch is pricing when compared to charge pipe options, like the BMS N55 methanol kit. Fuel-It options start just shy of $1,200 and can run up to $1,700+.
Despite the price, we believe this is an excellent kit for those who intend to rely heavily on methanol for fueling. Direct port methanol is the way to go if your goals are aggressive, and the Fuel-it options will help get you there. Great option from an excellent company.
Price: $1,199.95 – $1,727.95
Buy Here: N55 E-Chassis Fuel-It Direct Port WMI Kit
BMW N55 WMI Summary
Water-methanol injection offers tons of benefits for the N55. The power gains are great, and WMI also offers benefits similar to E85 and race gas. However, unlike E85, meth injection reduces demand on the N55 fueling system. It can help pick up some extra power without needing costly fueling solutions like port injection or HPFP upgrades. WMI does come with a few risks, but they can be mitigated with a quality setup and proper fail-safes in place.
Chargepipe WMI is a common, cost-effective option for the N55. It’s an excellent option for those who aren’t going to rely on methanol too heavily. Our favorite choice is definitely the BMS WMI kit. N55 owners looking to push methanol systems to the limit should definitely consider going for direct port WMI. Fuel-it offers some great choices, but the cost can be tough to swallow.
What’s your experience with N55 methanol kits? Are you considering one?
Drop a comment and let us know! If you are looking for more N55 content, check out our Ultimate BMW N55 Engine Guide.
Methanol is corrosive and prone to failure. I was a big proponent of methanol for 10 years until I saw the damage it will cause. I have documented corrosion and damage to braided supply lines, stainless steel supply line fittings, meth rated filters, as well as metal inlet pipes, and even engine components from even moderate methanol usage. Also if you get a pump, solenoid, or other failure you run the risk of seriously damaging your engine. I have owned at least 8 lots from all the major suppliers. From now on I will go with bigger fuel injectors, a bigger fuel pump, and proper fuel control. E85 is another alternative if your fuel system and tune will support it.
We totally agree that E85 is the best fueling solution. Unfortunately, E85 can be tough to find in many parts of the country and world. We’ve never been fans of relying heavily on WMI, but it does have its benefits when used primarily for cooling/knock resistance.