No time is wasted in deceleration and acceleration, so P4 or P7 doesn't matter much.
Few years back, Gatimaan got RPM P7 as offlink and it still made NZM on time despite P7 being way inferior than P5 (pathetic TE after 120 kmph and MPS of only 140 kmph)
Therefore for non-stop long runs, clearance matters more than the loco.
please wait...Translate to HindiKoi samay ghatana ya badhana mein barbad nahi hota hai, isliye P4 ya P7 bahut farak nahi padega.
Kuch saal pehle, Gatimaan ko RPM P7 add kar diya gaya tha aur woh ab tak waqt par NZM pahunch rahi hai, jabki P7 P5 se bahut bekar hai. Iske baad 120 kmph ke baad sudharne ki samasya hai aur maksimum raftar sirf 140 kmph hai.
Isliye, bina rukavat wale lambe daure mein, license mahatvapoorna hai, loco se jyada.