It's about time we got around to writing a water methanol injection guide for the BMW N54. WMI is an excellent source of fueling for the N54, and comes with the added benefit of cooler intake temps. However, there are also some risks and things to consider prior to opting for methanol injection. In this guide, we'll discuss the benefits, risks, and power gains of N54 WMI kits. We will also include a few of the best options on the market.
N54 Water Methanol Injection Benefits
A few benefits of running an N54 meth injection kit include:
- Horsepower gains
- Cooler intake & internal temps
- Knock suppression
- Acts as additional fueling
- Partial intake valve cleaning
A lot of these benefits are intertwined as they all help the N54 make more power. They also help the N54 make the power with less stress on the engine. Ultimately, most choose to run a WMI kit for the horsepower gains. We'll discuss this a bit more throughout the post, but horsepower gains depend on many factors. Gains may be as little as 10-20whp on stock turbos with conservative tuning. However, they may be as high as 50-100+whp on upgraded turbos with more aggressive tuning.
Cooler intake temps of course means denser air and more power. Cooler internal engine temps reduce the chance of engine knocks. It also acts as additional fueling which may save you from needing expensive port fuel injection. There's a lot to cover in this post so we kept the discussion a bit less technical than we normally would. In summary, N54 meth injection offers similar benefits to running E85 fuel. However, E85 requires demanding fuel flow while WMI actually reduces fuel demand.
N54 E85 or WMI?
We still believe running E85 on the N54 is better than running meth injection alone. The N54 loves high octane and is severely handicapped without it. The problem - not everyone has easy access to E85 or high octane racing fuels. This is where meth injection comes into play. Methanol is actually considered a high octane fuel. It is, however, highly flammable and easy to ignite. That's part of the reason it's water methanol injection and the most common mix is 50% water and 50% coolant. More on that later.
Also, even for those with access to E85 you can run an E85 mix coupled with meth injection for the ultimate cooling, power, and knock resistance. Dependent upon the health of your HPFP and injectors, the N54 can usually run 500-550whp on E40 or E50 fueling with a stage 2 LPFP. Throw in a WMI kit and you may be able to make 600+whp. We could go on and on. Point is, WMI has a lot of upside. However, those shooting for big power that are planning on port fuel injection or HPFP solutions - 100% E85 is our preference.
N54 WMI Risks
As with almost all risks in life, there are ways to mitigate the risks of meth injection. We're going to discuss a few of the risks and then explain how you can avoid such issues:
- Loss of WMI flow
- Uneven distribution of WMI flow
- Highly flammable
Loss of Methanol Flow
Meth injection kits rely on a pump to move the water/methanol mix from the tank to the injectors. If that pump fails then the cylinders are starved of water/meth that's acting as fuel and knock suppression. If you're pushing the N54 to the limit and your WMI kit fails then you're looking at very real possibility of engine failure. One serious pre-detonation may send a rod through the block, bend the rod, crack a piston, etc.
This risk can be reduced by using proper fail-safe systems like integrating the methanol injection kit with the JB4. The JB4 will quickly pick up on the loss of WMI flow and appropriately pull boost to avoid catastrophic damage. There are many other fail-safe methods that we simply don't have time to cover. A quick search should yield results. Nonetheless, WMI integration with the JB4 is very simple compared to other options.
Uneven Distribution of WMI Flow
Somewhat similar to the above in the sense specific cylinders are starved of water/methanol flow. If you're injecting meth into the charge pipe then it's possible for the WM mix to not make it evenly to each cylinder. On the N54, cylinders 1 and 6 - at each far end of the intake manifold - may receive less flow. If you're relying on WMI too much then this may cause serious issues similar to above.
Direct port methanol injection is one way to avoid this issue. We'll be discussing port meth shortly. However, the idea is that you're injecting the water/meth mix just before the intake valves thereby ensuring each cylinder receives equal flow. That is assuming one of the 6 injectors doesn't fail. Though that is extremely rare. Another way to mitigate risks is to tune conservatively and not rely on meth flow too much.
Methanol is Highly Flammable
We could leave it at that - it's highly flammable. However, this hits close to home for us. Our 2007 335i almost caught on fire once. Not from running methanol injection, but rather from windshield wiper fluid. We live in Colorado and use wiper fluid intended for cold weather so that it doesn't freeze and crack the tank. Any guesses? Cold weather wiper fluid uses a high percentage of methanol.
Back to the story - we topped the 335i off on wiper fluid (higher than intended) and the old cap wasn't very solid. We then went for a hard drive on a 95°F day at high elevation up a steep mountain road. The wiper tank cap popped open and spilled wiper fluid on top of the engine cover while driving around a tight corner. Suddenly, smoke began pouring through the A/C and the engine stalled. We popped the hood to find a fire burning on the hood foam. It went out quickly once the hood was popped and that was that. Some older N54 WMI kits actually use the wiper fluid tank. Be cautious about how and where you mount the meth injection kit.
What is the Best WMI Mix?
Most N54's run a 50/50 mix and we tend to agree with this being a solid option. We advise against running more than 50% methanol. The S55 powered M4 GTS actually utilizes 100% water injection. Even injecting straight water will help with performance. Water is great at absorbing heat, cooling temperatures, and acting as a knock suppressant.
However, methanol is flammable which is what makes it additional fueling. It also has a high octane rating. Water and methanol both have their own benefits to offer. If you're looking for bigger power gains then you'll want to mix in some methanol rather than running straight water. Stick to 30-50% methanol and 50-70% water.
Charge Pipe N54 WMI vs Direct Port WMI
We'll keep this short in the interest of keeping things moving. Charge pipe methanol injection is cheaper on the N54. However, as discussed above, charge pipe injection may starve certain cylinders of flow. 1 and 6 are the most common as they sit on the far ends of the manifold. It's still a great option if you're not pushing things to the limit and/or running an E85 mix.
Direct port N54 WMI is a fair bit more expensive. It's also not possible to run port fuel injection and port methanol injection at the same time. Therefore, it may not be a great option for those looking to run port injection for full E85 in the future. However, it's generally a safer option if you're relying on methanol as fueling and pushing 550+whp (i.e not running E85 or race gas at that power). Port WMI is the way to go from a performance and safety standpoint.
Best N54 WMI Kits
Finally. Sorry for the lengthy discussions above, but there's a lot that goes into WMI. In this section we'll discuss a few of our favorite options on the market. There are a lot of options out there that we won't mention, such as AEM, Snow Performance, etc. Additionally, we highly recommend the JB4 tune for its simple WMI integration and safety features.
1) N54 BMS WMI Kit
Burger Motorsports, creators of the popular JB4, offers a charge pipe WMI kit for the N54. It's well priced starting at $419 for the full kit including the 1 gallon tank. Dual nozzle setups with the larger 2 gallon tank and billet tank cap will run up to $677. Of course, you also need an upgraded charge pipe with 1 or 2 built in meth bungs. However, we assume most people considering meth injection are pushing their N54 hard enough that they already have a CP upgrade.
The BMS WMI kit is highly proven with many in use around the world. The catch? It relies on the JB4 for integration. We love the JB4 and highly recommend it anyways, so we wouldn't call it much of a catch. It is, however, another added expense for those not already running a JB4. Though, the JB4 integration allows for extremely precise control of meth flow. The meth pump flow signal is also sent back to the JB4 allowing it to quickly back out boost if the WMI kit stops flowing for whatever reason.
It's a highly proven WMI kit with added safety features that non-JB4 integrated kits generally can't offer. All for a fair price from a company that's long been building awesome aftermarket BMW parts.
Price: $419 - $677
Buy Here: N54 BMS Water-Methanol Injection Kit
2) N54 Twisted Tuning Direct Port WMI Kit
Unlike the BMS kit above, the Twisted Tuning N54 WMI option is a direct port methanol injection kit. As we briefly touched on earlier - direct port WMI is the ultimate system for those heavily relying on meth injection. It's likely a bit overkill for N54's on stock turbos or for anyone also running E40+ fuel mixtures or race gas in addition to meth. If you're looking to make 550+whp on pump gas only then direct port meth is the way to go.
The price tag of $1,300 may be tough for some to swallow. Additionally, the price does NOT include a water/methanol tank so you'll need to source that separately. Depending on tank size, brand, etc expect to tack on another $50-200 for the WMI tank. Otherwise, this is a full kit to run direct port methanol, including Twisted Tunings controller, port injection plate, pump, meth nozzles, etc. If we were looking to run N54 direct port WMI this Twisted Tuning kit would definitely be our pick.
Price: $1,300 (+ cost of tank)
BMW N54 WMI Summary
Water/Methanol injection offers many benefits for N54's, notably the impressive power gains. It also offers benefits similar to E85 or race gas. However, WMI actually helps reduce demand on the fueling system rather than adding demand as E85 does. There are a few risks when running water-methanol injection. Though, these can be mitigated through proper integration, tuning, and fail-safes.
Charge pipe WMI is a proven and cost-effective method, however it's a bit less precise than direct port methanol injection. It's still a great option for stock turbo N54's or anyone planning to couple WMI with an E85 mix or race gas. Our favorite option is the BMS kit as its JB4-integration makes setup simple and the built in safety features offer peace of mind. Those heavily relying on WMI and/or pushing 550+whp are best suited to direct port methanol injection for its superior precision and flow. Twisted Tuning's kit is a great option for a solid price.
Do you have experience with N54 WMI? What kit and setup are you considering? Drop a comment and let us know!