Additionally I'm now testing the large plasma turbine. I can't simulate a flow rate of 7.8125mB/t of helium plasma, so I'm using a fluid regulator with 7mB/t, feeding into a large plasma turbine with a small fluxed electrum turbine. Also, I found that the optimal plasma flow on the turbine tooltip is rather deceiving - it's half the actual value.
Key constants:
Additional efficiency modifier = 7 / 7.8125 = 0.896, Turbine efficiency modifier = 0.8, Turbine optimal steam flow = 16,000L/s
What I expect:
Nominal plasma output = (16,000L/s * 40) / 20 = 32,000EU/t
Full-efficiency energy output = 7mB/t * 4096 = 28,672EU/t
Theoretical energy output = 28,672EU/t * 0.896 * 0.8 = ~20552EU/t
However, when I test my system, I get an output of 20,070EU/t (all hail the portable scanner! Just discovered it). Working backwards I get a full-efficiency energy output of 28,000EU/t instead. I'm not sure whether there is an additional modifier in here somewhere.