These are the only formula's I basically use, cfm = cid x rpm x ve% / 3456, hp = tq x rpm / 5252, rpm = mph x 336 x gear / tire, with those you can explain a lot of things but there the 3 basic formula's everyone knows, I mainly look at dyno data and generally come up with my own theory's/takes about what I see, which usually ends up in disagreement's.
And I think primarily that's because no formula can ever be exact. There are too many variables. Best we can do is use formulas, theory and book knowledge as a guide and that's about it.