What are the differences between power and the motor torque?
In this technical article we will try to explain in a very simple way some interesting theoretical concepts, related to the power and torque of our engine.
The engine is an air pump
"It works with air, not with gasoline." I have repeated this phrase on countless occasions throughout my career as a technical instructor. By inertia we tend to think that the internal combustion engine works thanks to gasoline, and therefore the more gasoline the more power, but this is not entirely correct. Actually the engine produces power (work) due to the heat released by burning the air it contains (combustion). Gasoline is only the "tool" to burn this air. Therefore, when we look for power in the first thing we have to look at is to increase the amount of air that enters and leave the engine and the heat that is obtained when burning it.
How to increase power
Taking into account the previous principles, we could say that there are 4 main ways to improve the power generated by an internal combustion engine:
-The air inlet and output can be modified to allow a higher air flow. For example, a Filter of greatest flow or a high performance.
-The combustion chamber or ignition can be modified to improve combustion efficiency and generate more heat (which expands more air and more work is obtained). An example would be the installation of improved butts or a competition ignition.
-An more complex way is to modify the engine to improve thermal transfer and reduce friction. For example with the use of cylinders with special coverage or Thermal tape In the escapes.
-The last a very effective way to improve power is to increase the displacement of the cylinders, installing larger pistons (Big Bore) or a more travel crankshaft (Stroker).
Power and motor torque
We generally confuse these 2 terms or do not give them the importance they deserve. The motor torque is the force that makes the vehicle change speed, that is, the force capable of accelerating the vehicle. The power on the other hand is the capacity to maintain a work at a certain pace. Imagine that you have to climb 10 boxes heavy by a ladder. An engine rises in 10 minutes, and another engine, with double power, would rise in 5 minutes.
The motor torque is directly responsible for the power achieved, and the faster the engine (RPM) turns, the more power.
This is why sports motorcycles need more than 10,000 rpm to deliver the maximum power, while an American bicylinder delivers its maximum power to a few thousand RPM.
To summarize it differently: the motor torque allows us to accelerate until obtaining a certain speed, and the power allows us to maintain that speed.
Differences between engines
So what is more interesting, to have a good torque at low RPM or a lot of power at high RPM?
Have you ever noticed the training of GP motorcycles, which have to be pushed to help them take speed when they come out at low RPM?
It depends on what we are looking for: if we like to be crouched under a fairing at a very high speed we will look for high revolutions for a maximum power, and although we will not have much torque we will not need it by having an aerodynamic set.
Now, if the pure acceleration has fun, that "kick in the ass" that never ends when the gas fist opens and notice the thrust force and the gross power from a very low RMP then ours is the torque.
Great "power" engines are usually short -touched and wide pistons, in order to reach high RPM. The high "par" engines are usually long race and long pistons, applying more lever and therefore more strength in the crankshaft.
How do we do it?
Taking into account the previous theory it is important to plan the steps to follow when we are going to increase the "joy" of our engine. Many users and professionals install high -power kits that force them to drive with the engine at high RPM when in reality what is being looking for is more torque, which would be achieved with other types of modification. It is therefore important to advise well and know what kind of effects will cause engine modification, to obtain the expected results.
Notwithstanding when we talk about American or similar bicylinder, the truth is that it is quite easy to increase the motor torque (and in turn the power), since due to the strict regulations they come very "decaffeinated" of origin.
In this type of engines we are interested in some modification that provides us with a torque curve as flat as possible, which will result in an engine with a lot of force and useful power in any RPM range, making easy and fun conduction.
Enhance and enjoy, that is the issue.
Frank Burguera
Article extracted from Choperon Magazine