Originally Posted by soontobesrt
FTR: Lot of people dint relize or know but old 6.1 was proven to make 450hp at crank on an enge dyno and through 20% loss calulations. Most of them made 360hp or so at wheels and at 20% loss that 450 at crank. Just so people know so really this new 6.4 makes probably i ballpark of 25+hp more than old motor side by side
By "proven" do you mean on SRT's dyno or on an engine builder's dyno? If it's not and exact duplicate test then nothing is "proven".
Considering this pulled 475, most certainly within the +- specs allowed for manufacturing and they advertise 470 it's not a huge leap to assume the number they quoted for the 6.1L was similarly close to their observed numbers. What means a jump from 425 to 470 or ~45 HP when you account for production differences, not the 25 you come up with when you compare apples to oranges.
Also, HP is a number, Torque is something you actually use and the 6.4L has a much stronger "area under the curve" which is what your butt will feel on the street.