HP= TV/325 (I think the 375 someone mentioned above is for mph)
because w =Fd
and Power = w/t = Fd/t
and V=d/t
so Power also = FV or TV
so using 1 HP = 550 ft-lb/sec
HP = TV/550
or in knots HP=TV/325
Doesn't help with the mental imagery though, as a -400 at 1 knot msl/isa etc is putting out around 700 ponies, whilst at 340 kts it's pumping 230,000 horses.