Yes, they are and different ways of calculating the number also. Those are not what class racers are running for hp, it is a factor to pair up racers. the real hp is much higher. Not a theoretical guy. No youtube, no calculators, no racing (my friends do that). Just built engines in the old days. Used to buy cars with 360's pull the heads, 727 trans, and 8 3/4 pig and send them to the scrap yard. A lot of back in the day has not changed. There are those who can, and those who can't. Who needs 750 on the street. If you seriously want that I can give you a contact for a "440" that will do more than that on pump gas. I am happy with around 300 real hp. Have fun playing with your calculator.