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Two internal combustion engines :

  • $250\,\mathrm{hp}$ and $900\,\mathrm{Nm}$ torque
  • $770\,\mathrm{hp}$ and $790\,\mathrm{Nm}$ torque

Which of the above two engines will be more powerful?

P.S. These specs are from NFS SHIFT, first one from 1986 COROLLA GTS and second one from BMW M3 E96. Both fully upgraded.

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    $\begingroup$ hp measures power, so the second $770{\rm hp}$ vehicle is the more powerful. It can output energy at a rate more than three times that of the $250{\rm hp}$ vehicle. Torque measures "twisting" effect on the output shaft; its ability to accelerate a vehicle is determined by the gearing and other transmission between the engine and wheels. $\endgroup$ Sep 20, 2015 at 10:42
  • $\begingroup$ Those numbers seem very wrong, particularly on the Corolla. $\endgroup$ Sep 20, 2015 at 18:33
  • $\begingroup$ The question is essentially about the difference between torque and power. In what way is that off-topic? $\endgroup$
    – rdt2
    Sep 20, 2015 at 18:51
  • $\begingroup$ @DavidHammen don't under estimate the 1986 corolla gts. A guy made a 1500 hp drag car out of it. $\endgroup$
    – Saad
    Sep 20, 2015 at 23:02

2 Answers 2

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The short answer is that the 770 HP is the more powerful. However, I suspect the question is about the difference between power and torque. 'Torque' is the rotational equivalent of force and if an engine is exerting a 'high torque', it's pushing hard. This occurs when the vehicle is accelerating, especially from rest. 'Power' is the rate at which energy is used and is related to the rate at which an engine consumes fuel. So, accelerating from rest is a high-torque, low-power situation. Conversely, a vehicle running at high but constant speed would be a low-torque, high-power situation.

Different types of engine have different abilities: steam engines and electric traction motors produce maximum torque at low speeds, i.e max torque at almost zero power. Internal combustion (I.C) engines don't work well at low speeds and maximum torque occurs at a different speed from maximum power. This is why you need a clutch in an I.C engine power train.

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The 770 horsepower one.

The torque just refers to the ability of the engine to turn the shaft, which is then converted by the transmission. However, the horsepower refers to the actual amount of power or 'acceleration' the engine can dish out. It is the job of the transmission to ensure that the engine has the ability to efficiently supply power to the wheels. Thus, you would expect the one with a higher horsepower to be more powerful, unless the transmission is horribly designed.

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