Online Horsepower Calculators
http://www.dragtimes.com/da-density-altitude-calculator.php
this one will give you the weather at any drag strip for the day...and lets you convert your time to a sea level with standard baro and humidity like the dyno does...
more eye candy...
the 71 Dart on 10-4-14 at Famoso Raceway 10.31 @ 127.22 converts to
Stock and Mildly Modified Naturally Aspirated Engines
10.068 @ 130.459 MPH
Extensively Modified Naturally Aspirated Engines
10.16 @ 129.34 MPH