The Dart has different torque figures for each individual engine due to machining tolerances etc.. there is no correction factor available. your torques for t/o must meet a minimum figure as set by an extensive test run after you change any of the parameters. new prop do the runs, new engine do the runs etc... Different torque mins based on temperature, whether you use W/M etc. RR has a circular slide rule where you set the WAT, and it gives a fuel datum figure for the trimmers. After t/o you pull the power levers to set 14,200 and set the trimmers for climb temps, shut off the W/M and do your after T/O's. All from memory haven't flown a Dart in nearly ten years so forgive any mistakes.