Difference between horsepower and torque in automobiles?

Question

Especially interested in understanding the wider band between horsepower and torque in diesel engines.

Answer 1

Torque is essentially the force the engine can produce. This dictates how heavy of a vehicle it can move, how much of a load it can carry/tow, how steep of a hill it can climb, etc. Torque is what makes a tractor work.

Horsepower is torque/time. How fast the vehicle can climb the hill, how fast it accelerates, etc.

Diesel engines tend to have more torque but less horsepower due to their design. The high compression ratios and high energy content of diesel makes for this. But power is robbed from the engine to achieve these compression ratios and RPM on diesels is limited, so horsepower isn't as high. The availability of large amounts of torque throughout its RPM range almost makes up for it.

Answer 2

In physics, torque can informally be thought of as "rotational force". The SI units for Torque are newton metres although centinewton meters (cN·m), foot-pounds force (ft·lbf), inch pounds (lbf·in) and inch ounces (ozf·in) are also frequently used expressions of torque. The symbol for torque is τ, the Greek letter tau. The concept of torque, also called moment or couple, originated with the work of Archimedes on levers. The rotational analogues of force, mass, and acceleration are torque, moment of inertia, and angular acceleration respectively. The force applied to a lever, multiplied by its distance from the lever's fulcrum, is the torque. For example, a force of three newtons applied two metres from the fulcrum exerts the same torque as one newton applied six metres from the fulcrum. This assumes the force is in a direction at right angles to the straight lever.

HORSE POWER A horse power (also rendered horse-power) is a now largely-obsolete machine for using draft horses to power other machinery. It is a type of animal engine somewhat more sophisticated than a horse mill. A common design for the horse power was a large treadmill on which one or more horses walked. The surface of the treadmill was made of wooden slats linked like a chain. Rotary motion from the treadmill was first passed to a planetary gear system, and then to a shaft or pulley that could be coupled to another machine.

Horse powers were used to power farm implements and industrial processes. Examples of machines that were powered with a horse power include the threshing machine, the corn sheller, pumps and machines for sawing wood. Horse powers were modular in that they could be attached to whichever implement they were needed for at the time, preventing these machines from needing to incorporate power sources into their design. They could also be used interchangeably with other forms of power, such as a hand crank, line shaft, stationary engine, or the PTO shaft or flat belt pulley from a tractor, which eventually replaced them.

The name of the horse power probably predates the name of the horsepower unit of measurement. (For reference the 1864 Webster's Dictionary defines Horse-power as “A machine operated by one or more horses; a horse engine.")

Answer 3

torque is a measure of how much a force on a object causes that object to rotate . power is produced by the hp of the moter to the rear wheels.