Detonation detection, what would you do? That is a great idea and a concern of mine. You think a knock sensor placed in the block drain plug, or near the intake track, would be sensative spot. It could be wired to a LED in the cabin on a voltage sensing circuit.
The box cannot be mounted underneath ? It doesnt get a shower of water when I pop the hood, but a few drops. So it is better the other way? Originally it was going to be placed in cabin. underneath the dashboard behind the glovebox and heat vent duct. Unfortuneately it makes a buzzing at operation and that was crossed off as a location. I could fashion a lexan cover from my nephews old rc car body. Might look strange.
Strange- These water injection / HHO systems I glanced. A water bottle with heet and a sponge to the vacuum port, is going to work?