Did any of you horsepower calculator guys ever use this

Imo, the real problem with all of these types of calculators/formulas is...... they’re usually pretty close...... on something.
So then there’s an assumption made that it should be close on everything....... when it clearly isn’t.

As I said in an earlier post, it’s pretty close for the power number on a 10:1 350 SBC with E street heads and an RPM intake, and a Thumper cam.

But, over 100 off on a 10:1 446 with a nice solid cam, Sidewinder Heads, and an RPM.

This calculator shows the hp/ci is a fair amount better for the 355 than the 446, when in reality it was better for the 446.