Get Schooled: Water Methanol Injection 101

Water/methanol injection has been around since the 1920’s, but really didn’t have much practical use until World War II. As we know today, a fuel-rich mixture produces more power, but it’s not because that extra fuel gets burned during combustion. Rather, the excess acts to cool the mixture as it turns from liquid droplets to vapor with the heat of combustion.

Supercharged engines were common in military aircraft, so that they could fly at higher altitudes, despite the less dense air. But rich mixtures compromise the range that the plane was capable of, so substituting another liquid for aviation fuel would effectively increase the range, or allow for more power by increasing boost which would increase the altitude the plane could fly at. In the automotive world, the technology has not been ignored.

The companies we are talking with:

Snow Performance – Snow Performance is one of the oldest names water/methanol injection in performance applications, and we talked with owner Matt Snow who also campaigns a blown NASCAR engine-powered Fox body Mustang that makes nearly 1000HP.  In the fall of 2004, the long standing world record in the quarter mile for diesels was broken twice using the Boost Cooler water/methanol injection system by Snow Performance.  Snow currently offers three kit levels – first with a simple pressure switch that activates the injection at a given boost level, stage two adds in a progressive controller box that allows the user to ramp the boost from a start to end point, and the stage three is a fully computerized version of the stage two progressive controller that allows for adjustments on the fly.

AEM – Talking with AEM Marketing Director Lawson Mollica, AEM launched their first system in 2007 that was progressively controlled. Since then, they’ve added a better progressive-rate pump and improved the check valve design. Most of AEM’s technology is in the controller; it has monitoring controls for fluid levels, monitors for system errors or open circuits, and a system test button for leak testing and priming. Their next evolution is their Water/Methanol Fail Safe Device. It has multiple outputs you can hook up to various safety functions, and an internal data logger.

We hook up with Snow Performance to explain everything you need to know about water/methanol injection!

Snow Performance offers their kit in three different stages while AEM utilizes one well-rounded option.

“Formula 1 dabbled in it for a while. They actually banned it because it caused the cars to go too fast and have too much power,” said Matt Snow owner and founder of Snow Performance. “OEMs started using it in vehicles like Corvairs and Oldsmobiles. Buick experimented on the Grand National in the 1980’s and picked up over 40 horsepower on a stock production engine.”

Only in the last decade has the technology of water/methanol injection really taken off in the enthusiast market. With advances in power, safer operation and the ability to get better fuel economy, available products and their sophistication have been on an upswing. For diesel engines, water and methanol injection does all of those things in addition to tremendously improving emissions. “We’ve latched onto the idea and then we put modern electronics onto it. Additionally, robust higher pressure pumps and mechanical parts makes the kits much more reliable,” said Snow. “We modernized the concept but it’s nothing we came up with by any means.”

How It Works

What causes two things you never thought safe to dump into your engine to be powerful and safe? Snow explains, “On a simple level, it’s intercooling and race gas combined. When you inject water and methanol into the intake stream, you cool the air as the liquids evaporate. When you get into the combustion chamber, it slows the flame, acting just like octane.”

When trying to increase power, the hard limit arrives in the form of detonation which, if uncontrolled, will result in physical damage to the engine.  Several external factors contribute to the onset of detonation, including engine operating temperature, intake charge temperature, air to fuel ratio, fuel octane level, overall fuel quality and engine ignition timing.

Beyond these, internal factors like compression ratio and carbon buildup in the combustion chamber or on pistons can have a direct effect as well. “It’s a very good anti-detonation tool for boosted cars. The limitation for how much power you can make, assuming your physical structure is sound, is the octane in your fuel which limits how much boost and the timing you can run in your engine,” said Snow.

In the end, it’s all about cooling. Once you have a cooler combustion process running, you have options available to you. Ideally, you want to increase power again to the point just before the onset of detonation. This can be done several ways, but combining higher boost levels with ignition timing adjustment is the most common route. “We have a video that provides a great description of the ‘what, where, why and how’ of methanol injection in gasoline engines that you can access from our website,” says Lawson Mollica of AEM. “It’s only about three minutes long, and I recommend that anyone who wants to learn more about how these systems work and how they can benefit your car view this video.”

Water/methanol injection can also be used on normally aspirated engines. High compression engines can use a 50/50 mix and see the kinds of benefits we’ve talked about for power adder engines. Even regular engines can benefit, but these most often use water only, with a lot of timing to improve fuel economy.

Finding Methanol and Mixing

Snow's Boost Juice is a pre-mixed one gallon jug of 49% methanol and 51% water.

It’s not that hard to obtain supplies of methanol and water mix. You don’t need to make a deal behind a convenience store on the bad side of town but rather you can order it from suppliers like Snow, VP Fuels, and even use some windshield washer fluids.

The easiest way to get your methanol is a premixed container of Boost Juice from Snow Performance. It contains 49 percent methanol, 51 percent water and can be shipped to you or picked up at a Snow Performance dealer. If you are using the windshield washer fluid container, Boost Juice is a good washer fluid and works as a de-icier. Boost Juice will give you a higher methanol to water rating over windshield washer fluid.

Windshield washer fluid can also be used but it must be blue in color with no additives and rated at -20 degrees F. The washer fluid is 30 percent methanol, 70 percent water but you can bump it up 50 percent mixture by adding three 12 oz. yellow bottles of Heet gas-line-antifreeze to every gallon of washer fluid.

If the methanol is mixed on its own it must always be “neat”, meaning no lubricants or additives in it. Ultimately the best mixture is 50/50 but ratios down to 30 percent methanol and 70 percent water can work well. “We recommend that people purchase straight methanol and mix their own injection fluid to get the best in performance and reliability,” explained Mollica.”The mix is easy; just create a 50/50 mixture of methanol and water. Stay away from methanol with ‘top lube’ additives and ask for M1, which is what straight methanol is commonly called. You can find it in race shops, race tracks… basically anywhere race gas is sold.”

Now where do you get straight methanol if you want to mix yourself? Before you start handling methanol on your own, there’s a couple of things you should know. Methanol is also known as methyl alcohol, wood alcohol, wood naphtha or wood spirits. Like any industrial chemical, it should be handled with due caution and respect.

Washer fluid can be the cheapest and easiest solution, though the -20 F versions can be hard to find in states that don't freeze.

Prior to 2006, Indy Car racing used methanol as a fuel. If you ever saw a pit fire, you’ll know that the flames are invisible, which can make for a nasty situation. Also, this is not the kind of alcohol that makes for drinks of a sociable nature. In point of fact, drinking it can make you blind.

Normal sources for methanol include industrial chemical suppliers and sources of race fuels. Online resources such as and may be helpful, but bear in mind that shipping flammable liquids has restrictions.

Methanol that has been unsealed for a long time tends to absorb water from the atmosphere and so degrades as a drag race fuel. Sometimes it can be bought from drag racers, but you’ll probably need your own container unless you’re taking theirs.

Now That You Have The Methanol, How Do You Tune It?

Where to begin? You must start out rich, with the largest valve in your horsepower/displacement bracket and with more flow than you think you need. After that, it’s about finding the “quench” point. Think of it like diving in the pool; you become quenched with too much water. Same idea here, you find the point in which you have too much water/methanol going into an engine.

Per AEM’s tuning guide, “Using a 50/50 mix of water/methanol is recommended for the best combination of air charge cooling and detonation control. With conservative boost and timing, establish a base AFR that is one point higher than your final target AFR. For example, if your final target AFR with water/methanol injection is 11.0:1, set your base AFR to 12.0:1. Once the base AFR has been set, start injecting water/methanol and adjust the injection flow rate to achieve your final target AFR. For example, if before injection your base AFR is 12.0:1 and then during injection your AFR drops to 10.5:1, reduce the water/methanol flow rate until your final target AFR is reached.”

The guide continues, “It is generally recommended that the flow rate of the injection system be changed in order to reach your target AFR and not your primary fueling. Injection flow rate adjustments can be made by changing your nozzle selection or by adjusting the “Start PSI” and “Full PSI” settings.” A properly tuned water/methanol injection system will usually support a typical “race gas” engine tune.

Matt Snow’s personal car is a Fox Body Mustang with a NASCAR type race engine producing over 1,000 horses on pump gas. How does a water/methanol system work on such a high horsepower application? First off, higher horsepower applications require extra nozzles. There are upward of five nozzles on some diesels pushing 1,200 horsepower, though Snow offer six different nozzles for different applications and power ratings from small snow mobile and boat engines to gas and diesel car engines.

Most companies like AEM and Snow both offer three car nozzles: small, medium and large. Typically the largest gas nozzle can handle roughly 600 to 650 horsepower and conservative boost around 15 psi, before the need of an additional nozzle in the kit. Most all kits from different companies come with two to three nozzles to choose from to help dial the application in.

Picking The Right Kit For Your Budget And Application

Certain components are going to be common among all levels of product sophistication, with the main distinction coming from the methods of control that are provided. All products will supply some kind of fluid reservoir, sometimes incorporating a low fluid level switch, and a fuel pump. Years ago, the pumps were barely more than washer fluid pumps with different seals, but they have come a long way since then. Suitable tubing, hardware and nozzles to spray the fluid will also be provided, allowing you to select the spray volume appropriate to your engine.

Snow Performance offers their kits in three different levels. Their Stage 1 kit includes an adjustable pressure switch that senses the boost level in the intake and will spray one continuous level of water/meth. The stage 2 kit has a start boost and final boost settings that are adjusted via a dial knob. The controller changes the speed at which the fluid pump is being driven and ramps the injection over the start/peak boost values. The stage 3 kit offers a controller with a visual display and on-the-fly adjustability. The kit also creates a delivery map based on boost and/or EFI signal from just a few easy set points that you can adjust with the heads up LCD display.

AEM's single kit is similar to Snow's Stage 2. It has a start boost and final boost settings that are adjusted via a dial knob. The controller changes the speed at which the fluid pump is being driven and ramps the injection over the start/peak boost values. AEM offers an additional option that comes standard with their kit called “Boost Safe”. It is a safety system that is integrated into the standard kit and puts the car into a safe mode if there is any electrical failure like an overheated pump, voltage spike or a blown fuse via a trigger switch wire that can be ran to ignition, boost, or computer controllers. We will get more into this in the Engine Safety section.“We launched our progressively controlled system in 2007," said Mollica. "Since then, we’ve added a better progressive-rate pump and improved the check valve design."

Each kit comes with different sized nozzles to best suit the amount of power your engine is producing. The AEM nozzles are seen on the left and include an integrated check valve under the nozzle's screen. Snow Performance utilizes a more compact air brake type fitting with swivel end.

Engine Safety Add Ons For The Above Kits

Snow Performance SafeInjection module keeps track of liquid flow and acts if it falls to low for any reason.

Water/methanol injection allows for a much more aggressive tune. So what if the throttle was stomped and the water/methanol tank was empty? Well that’s not ideal because of the much more aggressive tune with more timing and boost can lead to detonation, so there are many safety features built in to keep an engine from going boom in a big way.

Snow Performance SafeInjection PN 30020 and SafeInjection Pro PN 30025

Snow’s SafeInjection unit monitors the flow of water/methanol in the system. When flow drops below the unit’s set point for a specified period of time, the fault trigger will go to a high state of 12 volt signal wire. In addition to the supplied red LED, it can reduce timing with an ignition/timing controller such as an MSD or other after market ignition box.

Additionally, Snow offers a solenoid used for turbo vehicles equipped with an aftermarket boost controller. In the event the SafeInjection activates, the solenoid will open the vacuum source for the wastegate, immediately dumping the boost pressure. Also for turbo or supercharger applications, Snow provides a solenoid to be used with a blow off valve or diverter valve with the SafeInjection system. In the event the SafeInjection activates, the solenoid will close and the blow off valve will open. The trigger signal can deliver up to 1.5 amps to drive a solenoid or relay.

Snow Performance’s new SafeInjection Pro takes safety to the next level.  It is fully adjustable and measures actual water-methanol flow, not pressure or current draw from the pump.

AEM Water/Methanol ‘Fail Safe’ Injection Monitor PN 30-3020

AEM offers their “Boost Safe” which is a safety system that is integrated into the standard kit and puts the car into a safe mode if there is any electrical failure like an overheated pump, voltage spike or a blown fuse. Most companies have a low level switch that warns you when the fluid is low and for AEM if it becomes too low it will also send the car into a safe mode off a trigger switch wire.

AEM's water/methanol 'Fail Safe' comes with tunable, PC-based software that allows you to set high and low side warnings. These warnings can trigger ignition or standalone devices to adjust your tune accordingly.

While the Snow SafeInjection offers a gauge upgrade, the AEM ‘Fail Safe’ Injection Monitor is an additional safety device comes with a compact flow sensor and gauge in one unit. AEM’s ‘Fail Safe’ actively monitors the entire flow curve. Flow versus injection rate data is continuously collected and any deviation away from an acceptable baseline flow curve will trigger an alarm output. This output can be used to reduce boost, pull timing, switch maps, or any other function to protect an engine from detonation in the event there is an unsafe operating condition.

Check out the video below that shows how AEM’s ‘Fail Safe’ Injection Monitor Works!

The AEM ‘Fail Safe’ features many options, including PC configuration software with USB connectivity, an “Auto Set” feature that automatically provides a best-suggested baseline configuration, an analog display gauge with user adjustable back lighting that can be flashed when an alarm is triggered, and an internal data logger that records injection and alarm status data. It includes one low side (ground) driver and one high side (+12-volt) driver that can be configured to turn on or off during an alarm condition. “We launched this with ‘Injection Monitor’ as its name—which is what it does—but its purpose is as a fail-safe device for these systems so if something should go wrong it can compensate for it and save the engine,” said Mollica. “So, that name will be changing. Our Fail Safe Device offers fully mappable maximum and minimum injection limits, multiple outputs you can hook up to various safety functions, and an internal data logger.”


While the idea of water/methanol injection has its roots deep in history, practical products using advanced technology have made it relevant for today’s performance enthusiasts. There is a little bit of homework involved to make sure you get a kit that is suitable for you and having a reliable tuner that is familiar with water/meth injection.  Whether the search is for more power on the dragstrip or better diesel performance on the open road, the benefits available from water/methanol injection almost add up to a something for nothing proposition. Compared to other methods for achieving the same goals, there are few if any contenders the reach as high on the value scale.

About the author

Mark Gearhart

In 1995 Mark started photographing drag races at his once local track, Bradenton Motorsports Park. He became hooked and shot virtually every series at the track until 2007 until he moved to California and began working as a writer for Power Automedia. He was the founding editor for its first online magazines, and transitioned into the role of editorial director role in 2014. Retiring from the company in 2016, Mark continues to expand his career as a car builder, automotive enthusiast, and freelance journalist to provide featured content and technical expertise.
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