I don't get why people think those calculators are more accurate then a dyno, any other time a rule of thumb or a formula is brought up it's dismissed as nonsense or at best a huge ballpark area. And since the dyno is supposedly unreliable there's no way to verify these formulas plus there's like 5 of them and they don't even agree with one another, to me they seem to tell you minimum hp needed if everything is setup a 110%.
So every car that weighs X lbs and goes Y mph is the exact same hp, I don't think so. What about the rest of the hp curve don't matter ? Same with tires, gearing, stall, aero, driver etc.. ?