Taking a Look at AEM's Water Injection Unit

Taking a Look at AEM's Water Injection Unit


We’ve been a huge fan of water and methanol injection in forced induction applications, mainly because it works! More power, increased torque and a larger window of tuning ability before the threshold of predetonation takes hold? Sign us up!

AEM has completely redesigned its Controller Modules for its HD Diesel Water/Methanol Injection systems for easier installation and programming, and has added kit enhancements to improve system performance and simplify installation.


How does Water Injection Work?

One of the most common questions we get here but also one of the most easiest to answer. Water Injection is literally the practice of injecting water into your intake stream to help combat predetonation. Most water injection systems are complete kits, with the pumps, lines and controllers that help provide the right mix of water to your air/fuel mixture. Proper levels of mixture and atomization create a slower more controlled burn in your combustion chamber, lowering intake temps, cleaning engine parts and providing more power, safety and efficiency to your engine.

Today we’ll be looking at the AEM lineup of water injection controllers and kits, and we’ve seen the good and bad of their kits having installed, sold and worked on their entire water injection lineup since their inception. Needless to say we feel AEM has really ironed out some of the issues that have plagued the early models, from water pump failure to primer failure, we’ve seen it all.


Water/Methanol for Diesels of all Boost Levels
AEM Electronics offers two different water/methanol controller designs for HD turbo Diesel trucks, turbo vehicles and forced induction applications.

One is a Boost Dependent controller (Kit PN 30-3301)with an on-board MAP sensor (up to 40 PSI) and a molded in nipple for a boost hose pickup.

The second HD controller (Kit PN 30-3351) features a multiple input design. The Multi Input controller can be programmed to work with a 0-5v signal from an external MAP sensor for Diesels running over 40 PSI of boost, or with a frequency based Injector Duty Cycle (IDC) signal, frequency-based mass airflow (MAF), or 0-5v voltage-based MAF signal.

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

AEM’s new redesign looks to have completely remastered the mixture control of the kit, which is one of the most important features. Without the proper mixture tables or controllers the water / methanol mixture may quench the fuel or negatively impact the combustibility of the fuel. Too little of the water injection and it will fail to have any effect on the engine, too much injection could cause total engine failure by way of hydrolock.

The second most important factor in this kind of system is the jets used to deliver the mixture into the intake stream. Cheap or improper jets can wreak havoc on your vehicle by delivering an unequal distribution of water injection, which may cause damage or engine failure. Stay away from jets that are larger than 1.0 mm or anything too large for you to scale back comfortably.


AEM and other vendors such as Aquamist or our own DIY water injection kit use the ever popular BOSCH 1985 jet, this means that the flow delivery better matches an engine’s need for water/methanol injection, which further optimizes charge air cooling and detonation control.

Does Water Injection work on all motor applications?

Yes it will. While a non-forced induction application may have less to gain from such a unit, a cooler denser charge of air is always a good thing for power. When you couple the factor of reduced peak temperatures as the water absorbs heat and vaporizes, but the alcohol / meth burns slowly providing a detonation resistant element to the combustion chamber.

The result can be higher power levels, increased engine efficiency and thus better gas mileage and engine operation overall. So, in addition to cooling the engine and preventing damage, water injection also can also somewhat improve the environmental effects of a vehicle, by slightly improving fuel economy and lessening the release of pollutants into the air.

Happy Boosting!