After the emissions and unleaded gas requirements manufacturers made engines with lower compression and released numbers that did include exhaust manifold etc - meaning cars appeared to “lose” anywhere from 30-100hp. The fact was they didn’t really “lose” any hp……the numbers were inflated b/c the customer never realized the advertised hp/tq because when they bought the car….they bought a car (that had a transmission, differentials, manifolds, etc) and not just an engine.
The math never changed, 1hp still = 1hp from 50 years ago. How the companies record and report hp changed. A 2022 Scatpack Charger puts out way more hp than 1970 440 6 pack Charger, and yes, way more than a 426 Hemi.
If you want to do a true test - throw the cars on a dyno and test the power to the wheels. General rule of thumb for a gas vehicle is you “lose” about 20% hp from the engine through the drivetrain, to the rear wheels.
I got a little egg on my face here! just looked it up and todays charger is 4400+- pounds... a 72 was only 3300+-...
all I know is when your attention is drawn by the sound of a new cars RPM increase you see a car making a lot of noise with very little acceleration. take away the hellcat and its HP, and looking at the rest doesnt boast much advancement in 50 years!! just saying...