Usually, when evaluating the characteristics of a car, most drivers, first of all, pay attention to horsepower. But no less important characteristic is the torque. And these two parameters are the most vital when buying a sports vehicle.
The experts from the Indy Auto Man know everything about powerful engines – the dealership offers a good assortment of used sports cars in Indianapolis. And here is their explanation of the difference between hp and torque, and recommendations on how to make the right choice.
The Essence of the Terms
Horsepower appeared long before the first motorized vehicle. It is a conditional index, as it denotes a relative level of performance of an average horse by determining the work required to lift 550 pounds by one foot in a second.
Scottish engineer James Watt introduced a new unit of power in horsepower, but in the SI system, the power unit was named after him – the watt (W). 1 kilowatt (kW) is equal to 1.36 liters. But in ordinary life, horsepower turned out to be somehow closer to the people, so we receive letters with a tax for the amount of horsepower in our cars, and not for kilowatts, and brag to our friends about the number of horses. Horsepower remains a popular non-systemic unit of power for vehicles. By the way, a typical horse has a maximum power of about 13-15 hp. It can give out about that much on a dyno in the 5-minute load mode. And draft heavyweights can give out even 25 hp for such a period.
Many motorists do not pay due attention to the torque figure in the technical characteristics and the speed at which it is achieved. However, the car is pulled forward not by the power itself, but by the torque generated by the power unit. The higher the torque and the lower the engine speed, the more pleasant feeling from the vehicle acceleration, and the higher the engine power in intermediate modes. That is why twin-charged engines often seem more pleasant to handle than more forced naturally aspirated ones, which must run at high speed to achieve maximum acceleration dynamics. And it is precisely for this reason that those who have tasted the joys of a good turbocharged engine no longer want to switch to atmospheric ones, which, even with similar power, accelerate noticeably worse.
Torque is measured in newton meters (Nm). It is closely related to power because, for an engine with a rotating shaft, power at any speed is easy to calculate, knowing the torque. Conversely, knowing the power, you can calculate the torque. And it is with it that we encounter in everyday life. For example, when opening the cap of a plastic bottle, we use exactly the torque, also called the rotational moment or moment of force.
Power shows the amount of work the engine does in a period of time, and torque reflects the ability of the power unit to do this work. For example, the acceleration of a car at a given time at a constant transmission ratio is proportional to the torque. But the acceleration time from one speed to another is proportional to the engine power in this speed range, in other words, to the work done.
Which Motor to Prefer – High Torque or High Power?
If the power indicators of the two motors do not much differ, choose the one with the higher torque. Especially, if you buy a car with manual transmission. The maximum torque figures and power in intermediate modes are more vital in this case. If you have to drive constantly at the limit, a more high-torque motor will not have an advantage, and it is better to opt for the one with more horsepower. But the indicators must be evaluated as a whole.
