Understanding Water / Methanol Injection On Diesels

What are the benefits of Water/Methanol injection?

  • Greatly reduced EGTs - Decreases of 250 degrees F are common using a 50/50 water/methanol mix. Increased EGTs are an engine killer in today's performance diesel world.
  • Low cost power - Where else can you get 50-100 HP for as low as $549? What other modification does all these things with one system?
  • Greatly increased air charge densities - 3-5 psi boost increases are common with liquid intercooling.
  • Decreased emissions - increased combustion efficiency means less particulate matter and NOX emissions.
  • Fuel economy increase - increase your fuel economy up to 10%-15% (1-3 mpg).
  • Great for towing - more power/cooler EGT's to haul the heaviest loads.

Why is Water/Methanol injection so effective on Diesels?

Unlike gasoline engines, the power in a turbo diesel is largely a function of fuel. The problem with continually adding fuel is that you create an over-fueling condition and reach a point where the exhaust gas temperatures become prohibitive (over 1300 degrees F). A 50/50 water/methanol mix will decrease EGT's approximately 200-300 degrees F while increasing power 50-100HP.

Power is increased through:

  • Air charge cooling - Water/methanol usually lowers air charge temps over 200 degrees F. Low air temps makes denser air charge which provides more molecules of oxygen for combustion.
  • Combustion conditioning - the methanol acts as a combustion catalyst as well as a cooling agent. Water vaporization inside the combustion chamber increases torque and power output through "the steam" effect.

Where else can you get this kind of power with cooler EGT's, reduced emissions, and more fuel economy?

Is this technology new with Turbo Diesel?

Water-methanol injection for diesel engines has been used extensively for years in high performance truck/tractor pullers. With the elevated boost levels required for peak power, water/methanol is a common means of cooling the intake charge and reducing exhaust gas temps. Also, truckers have used water injection for years to increase fuel mileage.

What power gains can I expect?

In diesel applications, no additional tuning is needed to maximize the water-methanol injection benefits.

  • A cooler, denser air charge is now delivered to the combustion chamber – this allows more diesel fuel to be burned than before.
  • The methanol in the injection fluid burns as a fuel. This directly impacts power production.
  • The water vaporizes in the combustion chamber, creating rapidly expanding steam which pushes down on the piston to create additional torque.
  • The extra power produced depends heavily on the concentration of methanol used and the volume injected. Typical power gains in 5.9L and larger applications with a 50% mixture of water/methanol are 50-100 WHP and a 100-150ft lb-ft increase in torque.


Can the Snow Performance system improve my fuel economy?

Yes. The MPG-MAX™ systems are designed to do just that. Both the diesel and gasoline MPG-MAX™ systems are specifically designed to inject a very small and precise amount of water/methanol under normal driving conditions such as accelerating away from a stop light or driving up a slight grade.

Diesel MPG-MAX systems benefit from the methanol directly due to the fact that it combusts as a fuel, allowing for brake specific fuel consumption (BSFC) to be reduced. Typical gains are 10-15% better fuel economy or 1-3 MPG. In some cases and in independent testing, gains of up to 30% have been observed in diesels.

What fluid can I use in my system?

  • Boost Juice: This is the best fluid to use and is Snow Performance’s 49% methanol, 51% water mixture that can be shipped to your door or picked up at a local dealer. (If you are using your washer reservoir as the injection tank, Boost Juice is a great washer fluid – works as a de-icer!)
  • Windshield Washer fluid: Only if it is blue in color and rated for -20 deg F. This means it is safe to use and made of about 30% methanol, 70% water. If it is another color or another temperature rating, do not use it. It should NOT have any extra additives or features. You can “spike” your Blue -20 Washer fluid to a 50% mixture by adding 3 ea. 12oz yellow bottles of Heet® gas-line-antifreeze to every gallon of washer fluid.
  • Mix your own: You just need to make sure the methanol is “neat” and contains no lubricants or other additives. We recommend a 50% mixture.
  • Ethanol: It is not as good as methanol, but it can be used as a 2nd best option if you can’t find methanol. It can also be mixed with water up to 50%. Do NOT use E85 or any other fluid with gasoline mixed in. It will destroy the fluid delivery part of your Boost Cooler® and instantly void the warranty.
  • Isopropyl/Denatured Alcohols: These can be used, but are not as good as methanol. They have a lower BTU, or energy content, and a lower latent heat of vaporization (fancy way of saying how much heat they absorb) as well as a lower octane rating compared to methanol.


Why Methanol?

Methanol is an extremely clean fuel with an excellent cost/benefit ratio. Its high latent heat of vaporization also makes it an excellent air charge cooler which means a denser mixture and more horsepower. Because of these characteristics, it is a better fuel than ethanol although it will work in a pinch. Isopropanol has different combustion characteristics and should not be used. Methanol is extremely toxic and should be handled with rubber gloves in well ventilated areas only. Care should be taken to avoid skin contact.

Is Methanol Safe for my Diesel?

Methanol makes an excellent adjunct fuel. Because it has a cetane number of 4CN, it makes safe power without spiking cylinder pressures.

"Combustion of neat methanol alone results in a cetane number of 4CN with reduced PM (smoke) and NOx. " see SAE Technical Paper #940326 "Combustion and Emissions Characteristics of Minimally Processed Methanol in a Diesel Engine"

Where can I purchase methanol?

Snow Performance sells a 51/49 water/methanol mix as Boost Juice™. If this is used exclusively, Snow Performance can lifetime warranty a system so long as the free registration card is sent in soon after purchase.

Methanol can generally be purchased where racing fuels are sold. Also, most gas line dryers like "Heet" are simply methanol. Suppliers of industrial chemicals can also supply methanol for a very reasonable price. Methanol can be purchased online at VP Racing Fuels.

-20 degree F rated, blue windshield washer fluid is acceptable for use as well, and is available at most service stations. Although some fluids rated to under -20 degrees F contain glycol and other copolymers, most windshield washer fluids are up to 40% methanol. Try to find one that displays "contains methanol" on the label and is good to -20 degrees F, with no additives or special ingredients and is blue in color.

Additionally, many sprint car drivers and circle track and drag racers use methanol as a primary fuel. They often have methanol on hand and will even sell methanol that has been un-sealed for a long time at a very low price. Just be sure that the methanol has NO additives or lubricants (such as top lube), as they are not needed and can damage the pump.

Can I use pure methanol?

While all components of Snow Performance systems are designed to be able to handle pure methanol, it is not recommended for a number of reasons.

Safety: Pure methanol is easy to ignite with a low 140F degree flash-point and burns with an invisible flame.

Performance: Water absorbs more much heat than methanol in the intake and inside the combustion chamber. However, water cannot be flash-ignited, so volume-for-volume, it is more prone to cause combustion quench. SAE studies on the effect of methanol as a fuel in diesel reveals a cetane of 4CN (increased ignition delay) as well as increased area under the Torque curve during the power stroke (as piston is going down after TDC) resulting in safe power (not from greatly increased cylinder pressure).

How much range will a tank of Water/Methanol provide?

Diesels use more fluid than a gasoline application, and are in heavier load states more often.

On a Stage 1 or 2 system, the factory washer fluid tank on a pickup truck (usually 1-1.5 gallons) will last a tank of fuel. This is for normal mixed driving with no towing and some aggressive acceleration.

On a Stage 3 system used for towing, a 7 gallon reservoir usually lasts 1-2 tanks of diesel fuel. In an un-loaded state, the 7 gallon reservoir will provide about 1000 miles of range. When towing, the 7 gallon usually lasts about 500 miles.

A standard Stage 3 system will use about 1 gallon of liquid for every 75 miles of towing. Many Stage 3 users take advantage of their stock washer tank or the special universal fitting included in Stage 3 Snow Performance diesel kits with a custom large capacity tank. Be sure to use a solenoid upgrade for any reservoir mounted in the rear of the vehicle.


Where can I mount my reservoir and pump?

The pump needs to be within about 24” (hose length) of the reservoir, and as low or lower than the base of the reservoir. It is a “pusher” pump, not a “puller” pump.

Engine bay: In the engine bay, the reservoir and pump can be placed almost anywhere, as long as they are not very close to exhaust heat, or in the path of debris from the road. Just be sure that the pump is at the same level or below the reservoir, and that the reservoir is not located higher than the nozzle. If the reservoir has to be higher than the nozzle, a solenoid upgrade (part number 40060) is needed to prevent gravity-feed.

Trunk/Bed mounting: This is fine, but again, the pump needs to be close to the reservoir and gravity fed. Lengths of 20-25 ft of tubing to the nozzle are fine. We always recommend a #40060 solenoid for rear-reservoir mounting. A solenoid is included with the #40016 7 gallon reservoir.


I don't have any room in the engine bay for a reservoir, what are my options?

Use the factory washer-fluid tank. A bulkhead fitting allows the use of the factory washer fluid tank as a reservoir. 50/50 water/methanol makes an excellent washer fluid. Stage one and two kits often utilize this strategy.

Bed mounted reservoir. The reservoir and pump can be mounted in the back of the vehicle. 7 gallon reservoir upgrade features extra tubing, a solenoid upgrade, and mounting brackets for bed mounting. We always recommend a #40060 solenoid for rear mounting with any reservoir/vehicle.

Where can I mount the nozzle?

The best placement of the nozzles is in the area around the inlet to the intake manifold or virtually anywhere on the pipe leading from the intercooler to the intake manifold. The nozzles can be placed at any position on the tube, so long as they are pointing at a 90 degree angle to the direction of airflow. The nozzles can be placed in a series or right next to each other. There is enough heat and velocity and flow through the pipe under boost to absorb the water/methanol regardless of the nozzle positions relative to each other.

Some intakes are pre-drilled for Snow Performance nozzles. As long as all of the airflow into the engine will pass by all nozzles used in the system, even distribution and cooling will result.

Placement before the intercooler or turbo(s) is not recommended. Cooling is not improved. Never mount an injector nozzle before a turbocharger compressor. Sending fluid through the compressor wheel that spins anywhere from 50,000rpm to 250,000rpm can erode the leading edges of the fine aluminum. Studies performed by SAAB, concluded that pre-turbo injection will over time cause cavitation on the turbo wheel leading edges.

Is it better to inject the water/methanol solution before or after the Turbo? Where is the best place for a few specific trucks? (Duramax, Power Stroke, 5.9L/6.7L Cummins CR).

There has been more discussion recently (especially on the internet) advocating pre-turbo injection. Most of the debate centers around increased atomization. You can probably get away with this in the short run if you inject a small quantity of finely atomized fluid (less than 10micron droplet) with a very low injection duty cycle. Also if you don’t care about turbo longevity (like some competition diesels where the turbo is replaced frequently) or you have a system that doesn’t atomize correctly and need the turbulence to help (low injection pressure and nozzles that aren’t designed to atomize correctly).

In diesels, especially where injection quantities are large in relation to fuel and where there is benefit to injecting at low/mid engine load states on up, it becomes a question of when compressor wheel damage becomes too severe as pre-turbo injection has been proven to cause compressor wheel erosion. The amount of erosion depends on the quantity injected, the size of the droplet injected, the speed of the compressor wheel, and the injection duty cycle (what % of total engine operation is water-methanol injected).

Also, the argument of reduction in compressor work per unit flow and the increase in mass flow rate doesn’t hold water in a properly sized modern turbo.

Sources: Snow Performance