I am aware of most of your explanations, be it probably less focussed on those Honda engines.
However, effective CR, isn’t that calculated by the amount of mixture taken in, and then calculated by the physical CR ?
Just to make sure i understand correctly. My english habits are mostly direct translating from my own native language…
Intake efficiency, for atmospheric engines is always less then 1.
So, even @ .7 is considered very good.
This varry’s with the rpm, and offcourse the cam settings, valve lifting and so on…
Higher RPM = lower intake efficiency…
Going from 0,5 to 0,6 = gaining 20% for a 5,5 Hp engine in my experience.
Adding a few drops of water/steam in the reactor, raises the RPM, tested under full load, from 2650 RPM to 3300 RPM.
So far, my experiments have been, on purpose, limited to un-modified engines, or only minor changes, achievable without equipments. ( easy to copy for unskilled persons)
I would love to go to the next level and build my owns , full fletched modifications… working on that 
At the moment i am also experimenting, on the trike, with partial methanol injection/carburator, methanol i derived from bamboo vinegar…
Very promising and fun…
If your friend is interested, i am all ears and available to work on the development for an special engine…
How do i measure my improvements on modifications on the intake ?
I make the engine rotate on an electric motor and measure the intake volume at any given rpm, modify and retest…
So, i am pretty sure about the progresses, if they are worth the efforts, and the more or less gain those modifications give.
Still so much i can and will learn…
Thanks for your input, those things are really teaching me, so much appreciated.
Drop by when ever you want, we can have some fun here