Here is a link of the i-VTEC intake valves operating both with and without the i-VTEC spool valve activated. It happens quick so watch close.
In the video you will see that the intake valves operate independently when the oil control valve is not energized. This is when one of the valves is using the economy profile cam lobe, and the other on the performance profile lobe. When the spool valve is turned on, the valves move in unison - this is when both valves are locked together and they are using the performance profile cam lobe.
Most have heard about the VTEC systems that Honda has used over the years. In most applications in the past the VTEC added extra performance when it "kicked in". This is not the case on the R18 and R20 engines like I am using. In this series it is actually the opposite. In this series of engines they actually go in to "economy mode" when the ECU senses low load, and otherwise it is in "performance mode".
So why go in to this much detail? You do not want this engine operating in economy mode for aviation use. How do I know? Because prior to learning this much about the system, I was advised some misinformation about the i-VTEC and I unknowingly ran it in the economy mode while under load on my test stand and I lost compression in two cylinders. While I cannot say for sure the true cause and effect because I have not done a teardown, I suspected it just ran too hot, even though I was keeping it at 13:1 A/F ratio.
The good news is that I picked up a 2015 engine with 13k on it for only $550, and was able to swap it in the test stand over the weekend.
I will post what I learn on the tear down...keeping and open mind that the cause may be unrelated but I wanted to share this so others may learn from my experiences.