An Introduction to Water/Alcohol Injection Systems

by Jeff Howerton
All images courtesy of the Author

How Does All This Apply to the MINIs?

Testing has shown the R53 responds well to WAI. With amazingly high IATs, despite what intercooler is used, and its appetite for octane in the timing maps, a properly applied system can give significant gains across the entire RPM range. If one wishes to use a simple single stage system, the midrange can benefit greatly and the top end will receive some IAT cooling. If set up to inject the proper quantity in the midrange, the top end may not get as much as it would like, but some is better than nothing. One could add a second activation point and solenoid/nozzle to help out the top end. If one wishes to move onto a progressive system, the difficulty comes in injecting the correct amount of water/alcohol across the entire RPM range. We have seen the PPS system has a limited dynamic range which limits its effectiveness across the entire RPM band. Many cars with superchargers have a MAF sensor which can be tapped for a relatively good signal to use for progressive injection. The R53 does not have a MAF sensor. Being supercharged, the boost profile is not linear with RPM either. Therefore, the boost signal is compromised for an accurate injection signal as well. This leaves few options for finding a signal respective to engine load for accurate injection. Combine this difficulty with some of the shortcomings of a PPS system, and you could be chasing many variables trying to tune a system correctly. That’s not to say a properly set up simple system cannot be effective, but one should know the limitations you are working with in formulating your expectations. For the R53, IDC is the most likely candidate to give an accurate signal for injection parameters.

After much testing and data logging, I have some observations that may be helpful in considering the final package. Tuning plays a pivotal role in how the car will respond to a WAI. If the car has pinging issues, as many stock R53s had from the factory (or the addition of a smaller pulley can cause), a simple system could provide good results. The WAI can suppress detonation, cool the IATs, and provide some additional octane which will advance the timing maps providing more power. If the car has been tuned properly, and does not have detonation issues even under hard use, the WAI system will have a smaller effect. The car will already be running optimum timing for its setup and will be mostly used to combat high IATs. If the engine is re-tuned to take advantage of the strengths of the WAI, the sky is the limit.

The one thing you need to know about the Aquamist system is that if you buy something else and truly use it, you'll always wish you bought the Aquamist, and will probably anguish over how to sell your other system to buy the Aquamist.