I would like to reason this out using simple physics. (If you don’t like physics, then move to the last line for a short answer)

    Suppose that your foot is on the accelerator pedal at a constant angle. (i.e., a constant amount of fuel is being injected into the engine every second). That would imply that a constant power P is being generated by the engine. Now, this power can be expressed as the product of torque T and rpm. In other words, P=T * rpm (here, rpm is the crankshaft rotation rate and not the rpm of the wheels).

 

Now the torque gets transmitted to the wheels. (Let us assume that the gear ratio is constant, and for simplicity, let it be 1)

The car (of mass m, say) accelerates with an acceleration given by a=F/m= T / R/m

Since R and m are constant for the car, the acceleration a is directly proportional to the torque T.

So the instantaneous acceleration will be more for a car with higher torque.

But wait, there’s a catch!

    It is the instantaneous acceleration which will be more for a car with higher torque. Because the minute there’s acceleration, the wheels will start spinning faster, and if you remember what I said earlier, P=T * rpm or T=P /rpm

So as rpm increases, torque decreases! So the instantaneous acceleration decreases as you start moving faster! (Again, assuming the engine produces constant power)

 

Brake Horse Power (BHP), on the other hand, gives you a much better indication of acceleration, simply because it denotes the amount of energy your engine produces in unit time, and this energy goes in increasing your car’s speed in the same time interval (assuming no air drag and all that).

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      Mathematically speaking, if you start from rest, and run your car at constant BHP for a specified time interval, you get the final velocity from the expression below.

So, for two cars starting from rest, the mean acceleration will be more for the car with higher BHP.

Okay, enough with all the physics! What is the answer to your question then? What is the more detrimental factor in deciding acceleration, BHP or Torque?

According to me – There is no simple answer. It really depends on the BHP and Torque curves of your car, and the speed range which you are considering.

Note: Once BHP and Torque are given, you really shouldn’t worry about cc (the engine displacement). Both BHP and torque are a consequence of a number of factors, one of them being cc.

 

SOURCE:  quora.com/joelmartis