Crank vs. rear wheel

A few thoughts and observations...
The poster was curious about crank vs rear wheel. Using teh most common slang definitions, he means gross crank, and rear wheel is always somewhere in the middle. That's because "net" for any given vehicle will be different wif the car has been modified. Factory net horsepower is all accessories on and functioning. That means AC, PS, smog pumps, alternator, mech fuel pumps, factory manifolding and exhaust, and factory air cleaner in place) So a modified car "Net" could mean nothing but alternator, or everything but AC, etc. So trying to compare Net and Gross is just confusing an not warranted.
Now in regard to factory ratings... Nothing is iron-clad correct. Not mechanical specs, not horsepower, compression ratios, or option packages. "10.5:1 383 HPs" are really about 9.2:1. "10.5:1 340s" are really 9.4:1. "8.5:1 340s" are closer to 7.5:1. All because the specs are all way off in execution. During the 60s and early 70s all manufacturers went with gross ratings. But there's more. They didnt use a single pull for the rating. They took the engine and modified the jetting, timing, and advances to maximize the horsepower for each level. So a 440 would be set up and tested for highest possiblt power at 1K, 2K, 3K, 4K rpm, and the top reading for each rpm point was used. Not to mention the "dyno mule" blueprinted and supertuning that went into them... Plus the fact that as the horsepower wars went on... they all under-rated the highest engines. First for race rules, then later for insurance. So really... nothing in print is really accurrate for a variety of reasons. Personally I think the differences between Net and Gross crankshaft output ratings is a moving number. It's not a percentage. A non-CA emissions 318 2bbl, with AC and PS will have much greater difference percentage wise than a 440 4bbl non-CA emissions package will. Compare the losses for a single engine Gross to Net and I'd bet it's somewhere around 30-40 horsepower. Less for a factory performance engine that had a better air cleaner and manifolding.