As a matter of interest, does anyone know how EPR is measured on a high by-pass engine? Is it the ratio of by-pass air, or the ratio of the hot bit, or an amalgamation of the two?
If it is the former, and given the lack of deterioration of cold engine parts, I would imagine that N1 and EPR measure the same thing in a different way. If it is the 2nd (hot bit), then I would imagine EPR gives a more accurate indication of power, and if it is the third then I don't have a clue
Serious question though.
(And yes...I don't have a clue)