Hypothetical scenario, lets say you take a 13b rotor and fill in the bathtub completly making the rotor have a smooth face. I don't know what the actual static compression would be but lets say its 15-1 for the sake of this example.

First part: If you where to then alter the width of the rotor either by expanding it or contracting it the compression would not be affected correct?

Second part: If you where to alter the size of the trocoid expanding or contracting the apex to apex length of the rotor, then there would their be a fixed relationship between the size of the trocoid, the diameter of the rotor's stroke (diameter taken at the center of the E shaft within the rotor) around the trocoid and the size of the rotor right?

So would it not be possible to alter compression by changing the size of the troicoid?

 

i don't know. however, i am very interested in the answers. i have pondered your second question (about changing the size of the trochoid) on more than one occasion.