AEM Performance Electronics Water Methanol Injection System Evaluation


AEM water alcohol injection system
The system warning LED is mounted in the dash.  This lights when the system detects low fluid levels or an electrical fault in the controller.

From the pump we ran the water to the engine compartment and the nozzle.  We used the medium size 315 cc/minute nozzle which is recommended for applications from 250-400 hp. We mounted the nozzle fairly close to the throttle body because we believe that we want the water’s phase change from liquid to gas to progress all the way to the combustion chamber.  This causes it to pull as much heat out of the intake charge with the minimum volume of water as possible.  This is because water injection uses the fact that water has a high latent heat of evaporation and much of the benefit of water injection is from the cooling effect of vaporizing the water as well as combustion buffering of the water in the combustion chamber slowing the burn. The water changing to steam also scrubs the combustion chamber and plugs, keeping them pretty free of deposits.  If you mount the nozzle too far away, the water will all evaporate before it gets to the combustion chambers and some of the benefits will be lost, or more water must be injected with the risk of causing a loss of power or driveability issues.  At the nozzle we installed the supplied one way check valve.  The check valve makes sure that the water line will always be pressurized to the pump bypass pressure no matter how long the water line run is.  This speeds response and prevent siphoning pullover from adding unmetered water into the intake stream.

AEM water injection system
We mounted the atomizer nozzle fairly close to the throttle body.  In our experience its best to mount the nozzle from 6 “to 12” away from the throttle body.  Too close and the mist won’t mix with the air stream.  Too far and the water mist will vaporize too soon.  Ideally you want the phase change to vapor to happen from the point of injection all the way to the cylinders.  This gives the most gains with the least amount of water.

One of the biggest problems that we have had in the past is the assurance that the water injection system is working properly.  This is especially important if you are tuning the engine or boost levels around the water injection system.  If the water is interrupted then engine damage can result.  In the past we have had pump problems and clogged nozzles that were only detected when detonation was heard, not the best way to tell if your system isn’t working, especially for those of us who have a hard time hearing it.  The AEM system has a warning light but some other assurance that the system is working properly would be nice.

AEM Water injection system
We mounted the one way check valve as close to the nozzle as possible.  The check valve allows the system to always be pressurized and prevents pullover from emptying the line or siphoning water into the engine.  The check valve speeds response this way and protects the engine from damage.


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