My high school had a clear glass ethanol motor for the energy and transportation classes.
I got to play with it maybe 5 minutes
It had no throttle but did have A/F ratio & timing/spark. I also believe you could adjust the compression ratio.
Interesting to watch and if you could turn the timing just right you could make it reverse.
You could watch and monitor the RPM, fuel flow rate and you could also put a load on the motor and again monitor RPM, fuel flow rate and test different timings and A/Fs the whole while.
I really wish I could have taken that home.