Below is what I got from a google search. Does anyone have a calculator that estimates HP like they did before 1970? Or is there and estimated ratio that play's into the end results of "today's" HP calculators that will approximate the older BHP style? I would like to know how much diffrence I have made in this motor power wise, but I want computed estimates rather than gusses like ""This cam"" does ""This much..."" Etc...
The original HP rating was 325 @ 4800hp and 430 @ 3100tq. I understand that this was estimated at the flywheel with NO accessories and whatnot, and since it was what would these #'s translate into under SAE requirements?
These are big questions but I'm curious...
Brake horsepower (bhp)
Brake Horsepower (bhp) - The measure of horsepower at maximum engine output, minus power lost from heat, friction, expansion of the engine, etc.
hp (SAE)
In the United States the term "bhp" fell into disuse after the American Society of Automotive Engineers (SAE) recommended manufacturers use "hp (SAE)" to indicate the power of the engine, given that particular car's complete engine installation. It measures engine power at the flywheel, not counting drivetrain losses.
Prior to 1972 most American automakers rated their engines in terms of SAE gross horsepower (defined under SAE standards J245 and J1995). Gross hp was measured using a blueprinted test engine running on a stand without accessories, mufflers, or emissions control devices. It therefore reflected a maximum, theoretical value, not the power of an installed engine in a street car. Gross horsepower figures were also subject to considerable adjustment by carmakers: the power ratings of mass-market engines were often exaggerated, while those for the highest-performance muscle car engines were frequently underrated.
Starting in 1971 automakers began to quote power in terms of SAE net horsepower (as defined by standard J1349). This reflected the rated power of the engine in as-installed trim, with all accessories and standard intake and exhaust systems. By 1972 U.S. carmakers quoted power exclusively in SAE net hp. The change was meant to 'deflate' power ratings to assuage the auto insurance industry and environmental and safety lobbies, as well as to obfuscate the power losses caused by emissions-control equipment.
SAE net ratings, while more accurate than gross ratings, still represent the engine's power at the flywheel. Contrary to some reports, it does not measure power at the drive wheels.
Because SAE gross ratings were applied liberally, at best, there is no precise conversion from gross to net. Comparison of gross and net ratings for unchanged engines show a variance of anywhere from 40 to 150 horsepower. The Chrysler 426 Hemi, for example, in 1971 carried a 425 hp gross rating (often considered to be underrated) and a net rating of 375 hp.
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<font size=-1>[ This Message was edited by: FEandGoingBroke on 3/16/06 4:45am ]</font>
