Water Methanol Injection Systems A-Z

Water methanol injection remains a popular upgrade within the high performance automotive market. It’s hard to believe that injecting water and anything else into an engine in the quest for more power can actually be a good idea, but the truth is that water methanol injection is beneficial to all forcibly induced and naturally aspirated engines-if done properly. The main function of water methanol injection is to prevent detonation, but that’s not to say it can’t also increase horsepower/torque output by 10 to 15 percent with proper tuning.

What is Methanol?

Methanol is an alcohol compound comprised of one carbon atom, one oxygen atom, and four hydrogen atoms (CH3OH) and is also referred to as wood alcohol, carbonic acid, and methyl alcohol. This poisonous, flammable, and relatively volatile liquid is naturally occurring, and domestic uses date as far back as the third millennia B.C., when Egyptians used methanol in their legendary embalming processes. It was first synthesized in the 1600s, and was later combined with water and used during WWII in supercharged fighter planes and bomber engines. After a few fast years, it was even banned in both F1 and NASCAR in the ’60s for adding too much power to competition engines.

Why is methanol used? 

Methanol is a very high-octane fuel that is extremely resistant to detonation. Its high latent heat of vaporization also makes it an excellent air charge cooler that means a denser mixture and more power. Because of these characteristics, it suppresses detonation more effectively than ethanol or iso-propanol.

How does it work?

Simply put: it helps prevent detonation. Substances heat up when they’re compressed, and in traditional gasoline engines, detonation-or “pre-ignition”-occurs when a cylinder’s air/fuel charge compresses and heats to the point of auto-ignition during the compression phase, before it can be lit at the proper time by a spark plug. If this occurs a few degrees of crank rotation in advance, the consequences may not be bad. But if it occurs farther back in the compression stroke, in high-power instances, it can easily destroy an engine’s internal components. Water methanol injection systems deliver a finely atomized mist of a water methanol mixture to an engine’s cylinder charge, and as the mixture absorbs heat and vaporizes, temperatures inside the cylinder are reduced and the propensity for detonation is decreased. Today’s newer, knock-sensor-equipped vehicles are very good at staving off detonation by retarding ignition timing the moment detonation-also known as “knock”-is detected, but do so at the cost of severely decreased power output and fuel economy.

While water is not combustible, it has a greater capacity to cool intake charges than methanol alone. This is why most manufactures recommend that a 1:1 mixture of meth and water be injected into your engine. Methanol also effectively increases the octane rating of fuel, giving the benefits of running higher octane levels. The evaporative effects of the water, plus the octane boost of methanol, allows your motor to run more advanced ignition timing and/or boost to create additional power with proper tuning. A general rule of thumb is that an engine will output one percent more power for every 10 degrees intake temperature is decreased. Many enthusiasts have found the benefits of using water methanol injection equivalent to running race gas, but without the high price tag.

What type of power gains can you expect? 

Depending on the system, timing can often be advanced 10 or more degrees when a water methanol system is used. Boost can often be increased five or more psi. When combined with the cooler air intake charge created by the water and methanol, these changes can net a horsepower increase of up to 20 percent in power-adder applications. In naturally aspirated applications, horsepower gains of 5-10 percent are possible, making methanol injection one of the best bang-for-the-buck power upgrades for your car.

Can water methanol injection damage my engine?

With most aftermarket parts there’s always the possibility of damage, but not if the unit is installed and used properly. As long as the injection system is working properly, it can only do good things. Since the water and methanol will help dissolve carbon build-up, it can keep your spark plugs, valves, and combustion chambers very clean, too.

Can you run just water injection without methanol?

Yes, but you will not be able to take advantage of the octane-boosting properties of methanol, thus you will get cooling from the water, but no increase in octane. Without methanol, you may not make as much power.

Do these systems work on naturally aspirated engines?

Yes, it can be used on N/A applications. Generally, it’s used when someone needs more octane or is having problems with detonation.
With stock compression engines (10:1 compression or less), you can gain up to 15 horsepower with full timing and achieve more effective air/fuel ratios and increase gas mileage. In naturally aspirated high compression engines, water methanol injection system allows the use of pump fuel in most situations, making it a more budget-friendly alternative to race gas. Plus, the colder, denser intake charge delivers more power and allows for higher timing advances.

What are the most important issues when setting up a methanol kit?

The most important issue is proper nozzle sizing. It’s far too common that people go off the “if a little is good, more is better” mentality-which is why we recommend a 1:1 ratio of water and methanol. The motor can only ingest so much water in the combustion chambers before it loses power.

What supporting upgrades are required for water methanol injection?

At minimum, you should have some sort of engine management that can be tuned to adjust timing, boost, and fuel curves to compensate for the octane boost and cooling effects. You do not need an aftermarket intake, exhaust, intercooler, or strengthened internals. Although, with more supporting mods, more power can be made.

Is a high-psi pump necessary to feed methanol? Why not use the factory windshield wiper pump?

Water methanol must be injected above 60 psi to properly atomize into the engine. Pressures lower than that will reduce the cooling effects, since the larger droplets exiting the low-pressure pump reduce total surface area, and will cause little to no gain in performance.

How long will a tank of water methanol last?

This depends on a few variables such as power, injection system, settings and driving style. However, a 3-quart tank will typically last around a tank of gasoline in most engines in the 200-500HP range. Most systems include some sort of fail-safe device that reduces boost or adjusts timing curves in case the flow of water methanol is exhausted or suddenly drops.

Is an intercooler necessary?

50/50 water methanol will provide all the density increase/detonation control needed to handle up to 30 psig of boost. However, an intercooler and water methanol injection together would provide even greater benefits, especially beyond 30 psig of boost.


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