Water/Alcohol Injection

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Terms and Acronyms you should know:
WAI: Water/Alcohol injection
MAT: manifold air temperature
IAT: Intake air temperature
VE: volumetric efficiency
HSV: high speed solenoid valve
Static: doesn’t change/vary
Shurflo: the manufacturer of most WAI pumps
Single stage: refers to kits that do not vary flow rate
Dual stage/progressive: refers to kits that do vary flow rate

What is Water/Alcohol injection?
The easiest way to explain WAI is by comparing it to fuel injection. The same concept lies behind both systems. Fuel injection systems normally consist of the following:

1. a tank
2. a pump
3. lines/tubing
4. injectors.

The purpose of the system is to deliver fuel into the engine in the form of droplets, which mix with the air flowing through the intake manifold. The same is true for WAI systems. They consist of functionally equivalent components to those listed above, which deliver water/alcohol in the form of small droplets.

What is the purpose of WAI?
It all comes down to the basics. The amount of power/torque an engine generates is dependent on the amount of air and fuel that manages to make it inside the combustion chamber. Though oversimplified, the formula “more air + more fuel = more power” is generally true. This is why heat is the enemy. Hotter air is less dense; it contains less molecules per unit of volume than colder air. So if you have two identical 3.0L engines at 100% VE, the one with cooler MATs will fit more particles of air inside the combustion chamber, and therefore, make more power (assuming fuel output is also greater). Enter WAI. Water injection decreases air temps by using the heat in the air to vaporize the water droplets. Alcohol is a very stable, highly detonation-resistant fuel. Individually, and especially together, these fluids can tolerate more heat and harsher conditions than just “premium gas” before knocking. No knock means more aggressive tuning can be implemented (leaner A/F ratio, advanced timing) which results in more powwah!

Who will benefit from WAI?
Those with high MATs:
With this in mind, it is not surprising that WAI is most beneficial for forced induction applications. The MATs for vehicles equipped with turbos or superchargers are, by nature, high—much higher than IATs. Non-intercooled or heat-soak prone intercooled vehicles suffer from even higher MATs. The higher the MAT, the more pronounced the effects of WAI are.

Those with high Compression:
Even if you do not suffer from high MATs, if you have high static or dynamic compression, WAI may benefit you as well. High compression engines do not tolerate even moderately high air temps or low quality fuel very well. However, when conditions are ideal, they shine. WAI can provide these ideal conditions (to a certain extent) for peak performance, 24/7!

What’s the catch?
A WAI kit can be pieced together for as low as $150. HOWEVER, there is a reason why $1000 kits exist:
1. Fail safes:
If you are running a high water/alcohol to fuel ratio and your kit stops working, your MATs will suddenly skyrocket, and you will be running insanely lean. High temps + lean A/F ratio = BOOM! Bye, bye, engine!
2. Mechanical differences:
Single stage (checkvalve):
Cheap WAI kits are very primitive; they are like on/off switches. Either it’s spraying x gph, or it’s not spraying at all. But instead of the transition being instantaneous, there’s lag. It’s supposed to be spraying, but it’s not. Now it’s supposed to stop, but it hasn’t. The result? Unpredictable, sudden surges and dips of power. Now you have power, now you don’t. It’s time to shift… will you still have power? If you have time to stare at your rpms, maybe you can guess. “It’s not really a big deal,” you think, “as long as it doesn’t bog like last time.” Sound fun? Maybe if your car is a drag queen.
Single stage (solenoid):
Now, let’s say you manage to fix the lag problem with a solenoid. As long as you stay above x rpms and x psi, you’re fine. But why does the power plateau so early? It doesn’t “keep pulling.” Don’t be surprised…your flow rate is static. Your cheap kit doesn’t care how fast your engine is spinning, how much air is entering your engine, or what the temperature is. No matter what the conditions are, it always sprays the same x gph. “That’s an easy fix,” you think, “I’ll just spend $400 on a dual stage kit.”
Dual stage (progressive shurflo pump speed):
You solve the flow rate problem (well, kind of. Now it can vary flow rate between 50-100%). Never mind that, at low pressures, some of the water/alcohol does not atomize properly. The problem is, the lag is back. You’re pretty much back where you started.
Dual stage (electromagnetic pump):
This
Dual stage (HSV):
Finally you have a kit very much like your OEM fuel injection system: static pump pressure and varying “injector” (hsv) duty cycles. No lag, and no atomization problems.

To be continued...