Quote:
Originally Posted by Diseasel300
Think of it another way: HP is how fast you pass someone. Torque is how much pedal you have to give it to keep the speed afterwards (this is why gas engines tend to downshift and rev higher when climbing hills and increasing speed).
Torque is a measure of how much work the engine will do at a given RPM. It's why diesel pickups can tow HUGE loads and get good fuel economy on the highway but can't pass a Yugo without some serious tuning. Power to weight ratio and gearing also come into play for the final driving experience.
Suffice to say, in the grand scheme of things, diesel powered cars are slow. Especially the old IDI style diesels. You can cruise all day on the highway and sip the gas doing it, but you're not winning any races.
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You're off a bit in your definitions:
Torque is a measure of twisting effort. Horsepower is twisting effort over time and is, by definition, a measure of WORK. Horsepower is a calculated variable (there is no such thing as a horsepower meter - if you see a meter reading HP on a dyno it's running thru a calculation and posting the result) and keeping the equation in mind helps make it clearer - HP= torque x RPM/5252 (a constant that corrects for the math). The RPM adds the time variable and so turns HP into the idea of twisting effort over time. To use an electrical analogy, volts = torque and KW hours (calculated from volts, amps, and time) = HP.
Dan