If you ever run one with the correct curve, you would never lock out or put it at all in by 2,000 again!
That's how much is lost!
My personal daily driver
66 Mopar 383 4bbl Holley
4200 pounds 2.78 rear gear
Factory a/c
20mpg highway while running antique RV2 a/c

Curve is determined by camshaft, compression, and cylinder head design.