Nope, not really. I never really understood either for a while. HP only really matters to me in bragging rights. I want torque and a good rev capability. That will make for a fun street car. Horsepower doesnt exist anyway, its just a number.
Nope, not really. I never really understood either for a while. HP only really matters to me in bragging rights. I want torque and a good rev capability. That will make for a fun street car. Horsepower doesnt exist anyway, its just a number.
On the contrary.. horsepower DOES exist.. although it is only a number, but so is your age, your bank account balance, etc. Horse power is the equivalent number of horses it would take to pull a wagon at the same rate as you.
Exactly, would take a hell of a lot of horses to pull a wagon the same rate as me buddy
I was only saying that no, physically there is no horsepower, its a measurement of Torque and RPM - the two things that really matter. Horsepower is a good tool, but again its only a number. The dyno doesnt measure horsepower, it calculates it.
James Watt (yes, the same "watt" used to measure power of everything from audio amps to lightbulbs) gave us the original horsepower. In determining the requirements for a steam engine to replace horses used in a coal mine for hauling coal up the shafts his observations led him to the conclusion that on average, a healthy horse could lift 550 pounds one foot in one second. This is equivalent to 33,000 pounds one foot in one minute. It turns out that his HP is equivalent to 746 Joules/sec or "watts".
Work is the moving of a mass through a distance against a summation of resistive forces like friction and the like. The rate at which work is done is the definition of power. While a small horse might lift 400 pounds a foot in a second, a big clydesdale might lift that 400 pounds that same distance in half the time.
In looking at the root definition of a horsepower, 33,000 pounds one foot per minute, you can already see the units: ft-lbs/min. In rotating machinery, it's necessary to factor in the 2-pi radians a moment arm moves through per revolution, which we already give the units 1/min to (i.e. RPM). 33,000/2*PI = 5252.11.
Power does clearly exist and can be measured as a result of doing work; e.g. quarter mile performance. The rate at which work is done is power.
While peak power is interesting and a source for bragging, the total area under the HP/RPM curve over the operating range of the engine is probably more important overall which is where big torque at lower RPM matters. Of course the ideal is big torque down low and, as torque falls off, the ability of the engine to spin to high RPM to continue making good power even as torque falls away.