Hi chrisfelce,
The following is the result of my research for the information you requested:
-Horsepower Defined-
"Horsepower is defined as the amount of energy or work required to
raise a weight of 33,000 pounds a height of one foot in one minute of
time or to overcome or create a force which is equivalent to doing
that amount of work. Therefore in simplified terms, a horsepower is
33,000 foot pounds of work done in one minute. However, horse power
may be required at various power points of the engine and the
calculation must be accordingly. For instance, the horse power
generated by an engine, as indicated by the power in the cylinders,
may not be the actual power which can be utilized for work as there is
the friction of the engine to be considered. Then there is "brake"
horsepower which is the actual horsepower delivered to the engine
shaft and which can be used for work, and the "effective" horsepower,
etc..."
Yesterday's Tractor
http://www.ytmag.com/articles/artint142.htm
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"Horsepower is a measurement of the engine's ability to do work. One
horsepower can lift 33,000 pounds up one foot in one minute.
Horsepower is measured over time. The more horsepower a vehicle has,
the more mass it can move in the same amount of time, or it can move a
fairly constant mass (the weight of the car) in less time. In simple
terms, to get a vehicle accelerating quicker, we need to produce
torque faster.
There are many different ways of measuring the power of an engine.
Brake horsepower is a common term and refers to the power measured at
the crankshaft using a "prony" brake. A prony brake was a simple lever
that was connected to the crankshaft with a brake. As the brake was
applied, the lever would deflect and power was indicated..."
CanadianDriver: Horsepower and Torque Explained
http://www.canadiandriver.com/articles/jk/020327.htm
=========================================
Brake horsepower: (BHP)
"A measurement of the actual usable power (not calculated power)
measured at the output shaft (usually the crankshaft) rather than at
the driveshaft or the wheels. Thus none of the auxiliaries (gearbox,
generator, alternator, differential, water pump, etc.) are attached.
It is called the brake horsepower because the shaft power is usually
measured by an absorption dynamometer or "brake." This is not the
brake on the vehicle's wheels but a testing device applied to the
shaft. This instrument is applied to stop or absorb the rotation of
the output shaft and returns a value."
Horsepower: (HP)
"A measurement of the engine's ability to perform work. One horsepower
is defined as the ability to lift 33,000 pounds one foot in one
minute. To find horsepower, the total rate of work in foot pounds
accomplished is divided by 33,000. If a machine was lifting 100 pounds
660 feet per minute, its total rate of work would be 66,000 foot
pounds per minute. Divide this by 33,000 foot pounds per minute to
arrive at 2 horsepower. In metric terms, it is the ability to raise
250 kilograms a distance of 30 centimeters in one second. It is also
equal to 745.7 watts."
Car Forums
http://www.car-forums.com/s7/t994.html
=========================================
Torque and Horsepower
"Torque is transferred from the engine crankshaft through the
drivetrain to the drive wheels. The power exerted vertically on the
pistons from the force of combustion causes the crankshaft to rotate.
To calculate the torque developed by the circular rotation of the
crankshaft, use this formula: torque = force X distance.
Although the technically correct term for torque is pound-foot, the
term foot-pounds (ft-lb) is more commonly used. In the metric system,
torque is measured in Newton-meters (Nm).
When the engine torque and rpm are known, the brake horsepower (BHP)
may be calculated with this formula: BHP = (torque X rpm) / 5,252.
Engine torque depends on the rotational speed of the crankshaft and
other factors. A graph may be used to compare the torque, brake
horsepower, and friction horsepower of an engine.
(see graph)
http://www.autosite.com/garage/subsys/03-09d.asp
The graph indicates that engine torque decreases after 2,500 rpm, but
the brake horsepower increases until 4,300 rpm. The friction
horsepower indicates the power required to overcome the internal
friction in the engine, and this friction horsepower increases
gradually in relation to engine speed."
Automotive Information Center
http://www.autosite.com/garage/subsys/baintl06.asp
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"There is a simple formula to calculate BHP:
BHP = 2 times pi times torque times revolutions; all this divided by 550.
Pi is 3.1416 and torque is in pounds-feet, and revs is revs per second."
Horsepower Calculations and Measurements
http://home.jps.net/~snowbum/hpcalc.htm
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-Horsepower and torque-
BHP = T x RPM ./. RPM
or
T = 5252 x BHP ./. RPM
BHP = Brake horsepower
T = Torque (ft/lbs)
RPM = Engine speed in revolutions per minute
-Formulas for brake horsepower-
horsepower = rpm x torque / 5252
torque = 5252 x horsepower / rpm
brake specific fuel consumption = fuel pounds per hour / brake horsepower
bhp loss = elevation in feet / 1000 x 0.03 x bhp at sea level
Racing Formulas
http://members.tripod.com/mopardaddy/id62.htm
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An interesting site:
Musclecarclub: Definition of Horsepower
http://www.musclecarclub.com/library/dictionary/engine-terms.shtml
Search criteria:
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I hope the information provided is helpful.
Best regards,
Rainbow |
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