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Fast forward to now. AEM gave me their latest version of a water injection system and I reluctantly agreed to install it on Project EVO IX. The more I studied the system, the more I felt better about it. The AEM system uses a powerful high pressure, 6 amp, 72 watt 150 psi pump. This is important because on a turbo car, the water injection system has to work against the boost pressure so a 20 psi windshield washer pump will actually not pump any water at all at 20 psi of boost unless the water tank is boost referenced. The pump also features chemical resistant fluroelastomer EDPM seals and a santoprene diaphragm so as not to be phased by ethanol or methanol in any concentration.
A high pressure pump will also create good atomization with the right nozzle. Good atomization is important for proper distribution of water mist in the intake manifold. A unique feature of the AEM pump is an internal bypass which allows it to be constantly running. This is important because it ensures fast response to demand and a consistent, smooth delivery of evenly atomized water to the engine. In fact, the quality and consistency of atomization is greatly improved with the constant on pump. With the constantly running pump, we noticed the fast response and felt confident about it even with our very remotely mounted pump. With other systems we often have felt surges, detonation and lag when the water system activates, especially if the throttle has been pushed hard enough to activate the system after a few minutes of light throttle due to operational lag. Our AEM system never had any of these driveabilty issues due to the constantly running pump.
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| Brian Kono of Afterhours Automotive built this bracket that mounts the water tank, high pressure pump and in-line water filter cleanly in the trunk. We put everything including the battery in the right side of the trunk to offset the driver’s weight and help balance the front heavy EVO. |
Our AEM system came with a one gallon reservoir although an optional 5 gallon one is available. We also used the recommended optional in line water filter, important to help reduce the chance of nozzle clogging. We mounted our tank and water pump in the trunk, to help keep our weight distribution from getting out of line. Brian Kono of Afterhours Automotive built us a beautiful bracket to mount the stuff and keep everything sanitary.
The AEM system comes with an all important electronic pump controller. The pump controller reads boost pressure via an internal sensor and controls the water delivery rate. The user can easily adjust the fluid volume delivery by turning two screws, one for onset boost pressure and the second for final boost pressure. The controller will set up a linear slope of increasing pump fluid delivery volume between those two points. This really helps eliminate drivability bugaboos like low boost bogging that other water injection systems sometimes have.
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| The controller and activation switch is hidden cleanly in the center console. This was chosen for its easy access when tuning. |
The pump controller has internal detection of electrical faults, a fluid reservoir level sensor and has the option to cut boost via a switched ground if the system runs out of water or the controller malfunctions. The controller also has a warning light and an external warning LED which illuminate if there is a problem with the system. These are features that we wished our last system had, it would have saved an engine.
