Dec 02

DIY Water Methanol Injection System-Parts


What is a water methanol injection system?

A water-alcohol or water-methanol injection system is a system that sprays a fine mist of water and alcohol (typically methanol) into the intake of a combustion engine as an anti-detonant.  As a result you can run more advanced timing and or increased boost on turbocharged automobiles.  Additional benefits are a steam cleaning of the upper engine and cooling of the intake charge from the water changing phase when it hits the combustion chamber.



There are a number of water methanol injection systems available, they all work similarly and feature many, similar if not the same components.  Some systems operate using pressure switches and have a pulsatile delivery which doesn’t deliver as constant of effects.  Other systems offer proportional control but have limited programmability.  I wanted to utilize the multi-core architecture of the parallax propeller to allow for proportional control that is completely customizable.  Additionally, I wanted to offer an lcd screen to output the current engine load level as well as the load level of the pump motor or spray level.  Another feature of this diy water methanol system is a float switch that prints “tank low, please refill” when the tank drops below a certain level



A few requirements exist for a tank, mostly it must hold liquid and must be compatible with a mixture of 50% water 50% methanol and its desirable to have a non-vented cap.

  • Many people use window washer fluid tanks out of old cars, or even the car they are installing the system in.  Winter windshield washer fluid has high levels of methanol so these tanks are compatible.
  • I opted for a new tank from US Plastics , their multipurpose tanks specifically are made from HDPE which is compatible with water and methanol and look to be the exact same tanks offered in commercial water-methanol systems
Pumps used for these systems have specific requirements too, mostly they must be self priming, run off of 12v and be chemically compatible with water-methanol mixture.  12v self priming diaphragm pumps meet these requirements and serve this purpose well some commonly used pumps are the following
  • SHURflo 8009-541-236 $59.99  60psi 1Gpm great for smaller engines
  • SHURflo 8009-543-236 $79.99  60psi 1.8gpm internal bypass
  • Aquatech pumps, Many commercial systems have switched to higher PSI aquatec pumps from SHURflo models in order to deliver smaller droplet size, keep in mind these pumps may draw more electricity.  Mainly this seems to be the 5800 series pumps, an important note you want to make sure you get the correct model pump head for the pressure/flow you are going for not all 5800 models are good for this application.  Make sure its 12v and has the pump curve you desire.
  • Cooling mist pump I’m pretty sure this is one fo the aquatec pumps but its a good option $139.95
Solenoid Valve
This component isn’t 100% necessary, but i’d highly recommend it when designing a diy water methanol injection system.  When the system isn’t running your intake will create some vacuum and actually suck in some water-methanol when you don’t want it and it won’t be a nice fine mist.  It’ll also take everything out of your line so you keep having to re-prime the system ruining the quick response of your system.  For around 20 dollars its worth having and many commercial offering have them.  It should be installed after the pump as close to the nozzle as you can, you really want to minimize the amount of tubing after the solenoid valve.   Some options are
Note:  a normally closed solenoid is desirable so you want be drawing current when there is no flow.
  • Mcmaster part 7876K68 $52.56
  • Ehcotech B20V I picked mine up here for around $25.00 shipped
There are a few things to consider when picking out tubing for this project including chemical compatibility, size, and temperature requirements.  I did my prototyping with polyethylene tubing however Nylon tubing is preferred because of its higher temperature capabilities and chemical compatibility.  I’d recommend using either 1/4″ OD tubing or 3/8″ diameter tubing depending on the overall flow rates/pressures of your system.
  • Mcmaster has nylon tubing 9685T3, 9685T4 $.85/ft, $1.81/ft respectively
  • Home depot sells polyethylene tubing in rolls for $3-5
push-to-connect tubing fittings, I picked up some from mcmaster and some from usplastics.com however the mcmaster ones with nickel plated brass were sharp looking and really well made.  I highly recommend this style of fitting for you diy water methanol injection system they are easy to use, quick to install and don’t link.
Float Switch
This component isn’t necessary for a water methanol injection system but its nice to know when your tank is getting low.  If you are running an aggressive tune that relies on the water-methanol injection for increased octane its crucial that you don’t run out of water-methanol or you may have detonation and break some parts.  I used a cheap float switch from amazon, they can also be picked up on ebay.  Some examples are
  • This is similar to the one i used $5.79
You can also find them on ebay for a couple of bucks but shipping will take longer.  Normally open (NO) or (NC) will work it just depends on what state the pin is looking for to trigger the low tank warning.  I used a normally closed version
Small systems will only need one nozzle, but larger systems like those used on diesel trucks often have a manifold and several different nozzles.  Some options are the following
  • Mcmaster nozzles part numbers 3178K75, 3178K76, 3178K77 depending on engine size.  The folks over at turbo mirage (great site, I highly recommend visiting it) recommend the 3178k75 for smaller cars up to 250hp, the 3178K76 for 200-450hp and the 3178K77 for cars above 400hp.  These nozzles work great and are around $8.00 each however they are only threaded on one side so they might be harder to install in some cars.
  • Devils own nozzles  $12.50-$20.00 each, threaded on both ends for easier installation
  • Cooling mist nozzles $26.95 each feature 90 degree fittings built in, they also offer a kit for direct port which is more expensive
  • AEM nozzle kit $63.85
This is where my project differs from others.  There are a few options for control.  You can just buy an off the shelf controller or even use a simple pressure switch and an off/on switch or a pressure switch.  Most controllers you can buy read off of an automotive input of some sort, possibly boost, MAF sensor, Injector PWM etc and then provide water methanol spray accordingly.  If you aren’t interested in creating a microcontroller based solution like I did you can simply purchase one of the following controllers.
I am going to develop my own controller to increase functionality and system adjustability.

Check out the Controller development here