soundguy said: (quoted from post at 10:44:07 11/24/14) Them lawnmowers use small horses!
Lawnmower engine ratings are about as valid as anything a politician says.
Deceptive tactics, like lab test engines running special fuel, different carb settings, no accessories, and rpm tested for hp calc rich before engine detonates
OEM engine HP ratings are only as trustworthy as the rater and the method of measurement used. Lots of variables can affect the measurement. Here are some examples of different types of ratings and how they are measured from Wiki. The emphasiswas added by me:
[Tb]he power of an engine may be measured or estimated at several points in the transmission of the power from its generation to its application. A number of names are used for the power developed at various stages in this process, but none is a clear indicator of either the measurement system or definition used. [/b]
In the case of an engine dynamometer, power is measured at the engine's flywheel.[citation needed] With a chassis dynamometer or rolling road, power output is measured at the driving wheels. This accounts for the significant power loss through the drive train.
In general:
Nominal is derived from the size of the engine and the piston speed and is only accurate at a pressure of 48 kPa (7 psi).[24]
Indicated or gross horsepower (theoretical capability of the engine) [ PLAN/ 33000]
minus frictional losses within the engine (bearing drag, rod and crankshaft windage losses, oil film drag, etc.), equals
Brake / net / crankshaft horsepower (power delivered directly to and measured at the engine's crankshaft)
minus frictional losses in the transmission (bearings, gears, oil drag, windage, etc.), equals
Shaft horsepower (power delivered to and measured at the output shaft of the transmission, when present in the system)
minus frictional losses in the universal joint/s, differential, wheel bearings, tire and chain, (if present), equals
Effective, True (thp) or commonly referred to as wheel horsepower (whp)
All the above assumes that no power inflation factors have been applied to any of the readings.
TOH
This post was edited by TheOldHokie at 07:52:26 11/24/14 2 times.
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