Since its a test engine sitting on a stand, I suppose I could put a calibrated amount of gas like in a quart jar with all things being equal. Then run the 4 conditions you mention. I would then run the sequence backwards to make sure I could repeat the results. Hmmmm. Any of you want to comment on how you would set this up in detail?
I did a SPC test on a small 1 cylinder engine in a college auto mechanics course to bring practical experience to the theory of SFC. Outside of remembering doing it I do not remember any details.
First I would do all the tests with the same weather conditions. Because you will of have removed any variables.
Also have the engine warmed up before you do any test to removed engine temp as a variable.
Use fuel from the same batch and unless you can think of something else we have removed all the variables.
Record the weather at the time of the test. Barometer, temperature, humidity. Because those three conditions will effect how the engine runs.
Then you should have valid results.
Now SFC tests have been done at a wide range of RPM's.
And you will see graphs of SFC from idle to max RPM.
There is no need for you to test your engine at high RPM's.
Though I would suggest a SFC test at 500 RPM idle.
A second test at what the engine's RPM would be doing 30 MPH.
Then a last test at what the engine's RPM would be doing 55 MPH.
Then if you ever felt the need to do more testing you can wait for weather conditions change to see how air temp, and humidity effects SFC.
