Editorial: Addressing the misconceptions of water injection

Hey guys, we’ve been chatting with a few people and there seems to be some misconceptions out there as to the affects of water injection.  Through our research and experiments with water injection over the past few years, we will attempt to clarify a few of these misconceptions.

The purpose of an engine is to transform the chemical energy found in fuel, into kinetic energy or motion. During this process which we know as combustion, a lot of heat is produced. Turbocharging an engine adds even more heat to the combustion cycle. This heat causes less air to enter the combustion chamber due to reduced density. Heat is also a major contributor to the phenomenon we know as detonation or knock.  Simply put, too much heat in the intake air and combustion cycle is detrimental to the production of power which we all enjoy.

To try and combat the issue of heat, we use big (some HUGE) intercoolers and run fuels such as E85, c16 and methanol which have a much higher resistance to detonation.  This is where water injection comes in.

Water has the highest specific heat capacity of any other liquid known to man and twice that of ethanol. This means that to raise the temperature of water, by so much as one degree, takes an enormous amount of heat energy. Water injection is so good at enabling turbo charged engines to produce massive power that it was banned during the turbocharged era of F1.

It seems that the number one misconception that people have with water injection relates to the view that it’s like hooking a hose up to your engine and turning the tap on. This couldn’t be further from the truth. A properly set up water injection system will use 15% -25% of the total amount of fuel being used. For example, if you had 4 250cc fuel injector that were operating at 100% then your water injection system would be set to operate between 150cc – 250cc. This could sometimes be equivalent to what your car breaths in when driving in the rain.

Another misconception of water injection is that it is bad for your engine components. This is false. The water enters your engine in a finely atomised state. This water is suspended in the incoming hot air allowing heat transfer to occur. This cooled air, with suspended water droplets, has now increased in density as it enters the combustion chamber.  Since there is more air due to an increase in the air density, we can add more fuel hence make more power.  But the benefits of water injection don’t stop there.

During the combustion process, the water droplets still suspended in the air boils due to the heat. This change of state from a liquid (water) to a gas (steam) absorbs a lot of heat from the combustion chamber. This protects the engine from detonation and control cylinder peak pressures, so much so that we can add more ignition timing and more boost and make more power. Another benefit of this change in state from water to steam is that the steam expands rapidly. The expanding steam helps to push down on the piston, increasing the engines’ torque.

The arrival of E85 has changed the level of performance we now expect from forced inducted vehicles. The performance benefits of E85 are well documented and it continues to grow in popularity as the preferred fuel amongst racers and tuners.The major draw backs of E85 though, in our opinion, is the lack of wide spreads availability and hugely reduced fuel economy. In many parts of Australia, including metropolitan areas, E85 is not commercially available.

Water injection provides a viable cost effective alternative, offering similar benefits without the previously mentioned drawbacks. There are many different brands to choose from, although keep in mind that you get what you pay for. Aquamist Systems are the most advanced aftermarket water injection system to date. They are built to highest standards and packed with features, including multiples failsafe strategies, to ensure seamless integration and operation. Click here for more details on the Aquamist range.

We hope this has shed some light on the benefits of water injection.


Orlando Barrett
Cool Runnings Engineering


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