Hp

["Denis, Jean" <Jean_Denis@domain.elided>]

AFAIK,
the SAE standard test method for determining horsepower once  was performed
(many years ago now, ergo the "inflated" '60's & '70's muscle car figures)
on naked engines (please, "motors" are Electric!), no accessories, no water
pump, etc.. But NOW, the SAE test includes all accessories like power
steering, alternator, etc.. Have no idea what the DIN test method would
involve but there are lots of variables, so it's bound to be different from
SAE.

BHp does refer to "Brake Horsepower", an engine is run up on a "brake
dynamometer" (very old, not really used anymore - last used one at college).
Big adjustable belt brake on a drum, belt tension increases friction drag on
the drum and increases the torque that  resists the engine's effort. Engine
is run at different speeds and belt drag is increased along with the
throttle to try to maintain a particular RPM. So at each RPM setting you
measure the belt tension, calculate the resisting torque (the work being
done, a.k.a. "The Load") and, with the RPM of the engine calculate the RATE
(or "speed") of doing work, "The Horsepower".

Does that help?
Hope i didn't screw up there somewhere (it can get confusing when talking
about power vs energy vs work & mass vs weight & etc.!)!

BTW: 1Hp = 550 lbs-ft of work done per second (like lifting 55 lbs, 10 feet
against gravity in 1 second), also = 746 Watts

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