I am a little confused by the HP estimates of my car depending which one I use.

If I put in my ET and weight with me in the car, I get like 628hp, I change it around and put in weight and hp to calc ET and I get like 780 at the flywheel...Who uses what, and what am I doing wrong?

Car with me in it is 3000lbs, and best 1/8th mile ET is 6.00 at 114.5mph.....Best actual 1/4 is only 9.66 with a 6.15 in the 1/8.....earlier in the season. Trying to figure out what the 6.0 is for HP

'70 Cuda,...605 EFI Hemi Street Car (6.20 best pass, 1.33 60ft)
https://www.youtube.com/watch?v=WYw6RA-k5Bk (6.25 at 108.75mph from inside car)
https://www.youtube.com/watch?v=3zQEb9uxFng (6.25 at 108mph from outside car)
https://www.youtube.com/watch?v=JCvfzsC4NgM (9.9)

'66 Barracuda AWB Stretched nose Blown 440 Car in build stage

'71 Duster Drag Car 400 Low Deck 512 best 6.002 at 115.44mph
https://www.youtube.com/watch?v=Znuo3jMUXTk