I wasn't sure about Ralphie boy, I just had a hunch that he may have been the one responsible for the reform. However I was fairly certain about the measurements. A quick search yielded an article at Edmunds.com
http://www.edmunds.com/ownership/tec...7/article.html) This is the pertinent portion:
....Rex writes: "In your article you are describing net horsepower, taken at the flywheel and wheel hp, taken at the driving wheels. Gross HP is the engine's power in perfect tune, with no accessories on it at all and no mufflers to restrict it, taken at the flywheel. Net Hp is also at the flywheel, but in regular tune with the mufflers in place, and all accessories on it."
When it comes to defining gross and net horsepower as the automotive manufacturers measure it, Rex is absolutely correct. Both of these terms refer to how much power is made at the flywheel, while my use of net horsepower referred to what was available at the rear wheels. Checking Webster's New World Dictionary, you'll find that one of the definitions of "net" is "after all considerations; final," which is what I considered wheel-driven horsepower. In my opinion, knowing how much horsepower an engine makes at the flywheel, with or without accessories, is pretty useless since that's not how we, as consumers, use an engine. The point of this column was to illustrate how much variation can exist between the horsepower figure printed in a sales brochure (net horsepower) and how much is available to motivate a vehicle (rear-wheel horsepower). Most of these variations come in the form of driveline loss, which can be substantial depending on the vehicle in question. We will update the "Horsepower" Tech Center to incorporate these terms as established by the automotive manufacturers. Once again:
Gross Horsepower: measurement of engine horsepower taken at the flywheel with no engine accessories attached, no restrictive exhaust system, and in a perfect state of tune (useless to the average consumer).
Net Horsepower: measurement of engine horsepower taken at the flywheel with engine accessories and exhaust system in place and in a normal or typical state of tune (also useless to the consumer).
Driven Wheel or Brake Horsepower: measurement of horsepower taken at the driven wheels on a dynamometer, reflecting how much power is available after an engine's accessories, exhaust system, emission control system and driveline losses have taken affect (very useful to know since it's a realistic measure of horsepower in the real world)....
Well, he almost got it all right. Brake horsepower is the measurement taken at the engine shaft, as opposed to 'indicated horsepower' (IHP) which is a measurement of power produced by an individual cylinder, not relating to exertion against a shaft and the resultant frictional losses.