HORSE-POWER DEFINED

New Zealand Herald, Volume LXXII, Issue 22166, 20 July 1935, Page 10 (Supplement)

HORSE-POWER DEFINED

" NOMINAL" AND " BRAKE " " One horse-power " is the capacity to lift 33,0001b. through one foot in one minute. Tho term horse-power is used to indicate the capacity lor doing work. " One horse-power" is the standard rate, and it indicates tho ability to lift 33,0001b. through one foot during the course of one minute. This is tho standard from which tho brake horse-power of an engine is based. Tho nominal horse-power is used,for comparison purposes only, and is based on tho 11.A.C. formula, which takes into consideration tho boro of the cylinders and tho number of cylinders. This formula is tho product of the boro squared, multiplied by the number of cylinders and divided by 1013. This constant (1613) is used when the measurements aro taken in millimetres. In regard to the power developed, this depends to a large extent upon tho tuning; also upon tho number of cylinders, for it must be realised that a four and a six-cylinder engine can be of tho same capacity, the rating and the actual power to a certain extent rely upon the size of tho bore, a four-cylinder job with a largo cylinder diameter may give a higher power output. Similarly, the valve timing, ignition timing, design of the combustion head and that sort of thing can all make a vast difference. ,