Hey friends we all know there is so much fuss about torque and about horsepower. Which one is more important, what’s really the difference between the two. But we know that both are important for our engine we are just confused about when torque is more important than horsepower and vice versa. Its my attempt to solve some of those queries. I have accumulated the data from various websites and I have modified them little bit to save my ass from the copyright act. I know this is a real confusing area of our studies so please let me know that this technical post hasn’t obfuscated the situation. All the best.
Torque really measures the twisting power of the engine. Torque is in direct relation with the acceleration; the more torque, the faster you'll get up to speed. Horsepower is something that will keep you at that speed once you've accelerated and is in direct relation to the torque readings. So a high-torque, low-horsepower engine will accelerate well but won’t be able to maintain a high speed. Similarly, a low-torque, high-horsepower engine won’t have much acceleration but will be able to go at a fair speed once it's going.
We all know that most large commercial trucks and heavy-duty trucks have diesel engines. Diesel engines produces more torque. We know that a diesel engine doesn't have spark plugs and uses compressed air to ignite fuel, the piston then has to travel a longer distance to compress enough ignition. This increases the stroke of engine which increases the torque.
There has been so much debate on the horsepower and torque. In the end, we come to conclusion that while towing torque is more important than horsepower. The power at low rpm provided by high levels of torque allows you move huge loads without much effort. some diesel trucks produce twice as much torque as they do horsepower at near-idle RPM levels -- meaning that they can start pulling something very big quite easily.
Horsepower is important because it allows a car to move faster on the highway and at high rpm. However, if you can't get that load off the line, there is no meaning of all that horsepower which your engine can generate.
Horsepower and torque both influence acceleration. Horsepower influences the acceleration at high rpm or at high speeds, whereas torque aids acceleration from a stopping point. Because of this, torque is known as low-end power.
HP = TORQUE x RPM ÷ 5252
Note that at 5252 RPM, torque and HP are equal. At any RPM below 5252, the value of torque is greater than the value of HP; Above 5252 RPM, the value of torque is less than the value of HP.
Torque is low end power while horsepower is high end power. Horsepower provides highway passing power when your engine is revving hard, allowing you to accelerate at high speeds, while torque gives you low-end power and the ability to move quickly after stopping.
If you want to accelerate at a very fast pace from stop or from low speed you need high torque but when you are already going at a high speed and then you need to accelerate at a still higher speed for example to overtake a car or a truck at a highway then my friend what you need is high horsepower.
Torque allows you to do the work while horsepower allows you to do the work quickly. Horsepower will allow you accelerate when you're already moving and towing something big and heavy behind you.
Torque drops after a certain RPM. Why?
After a certain speed torque begins to decrease. The reason is drop in volumetric efficiency. We know that the condition for MBT is maximum amount of charge inducted per cylinder per cycle. MBT occurs at a certain speed and if you keep on increasing speed torque will go down because engine won’t be able to breathe properly.
Power increases even after torque starts to decrease. Why?
Power is the product of speed and torque. Initially, decrease in torque is less compared to increase in speed so the overall product of torque and rpm increases and hence power increases. But ultimately the decrease in torque becomes large enough and it simply outweighs the increase in speed and hence the power decreases.
Even after all these statements and discussion there still are questions unanswered. Like why the torque curve of a diesel engine is flatter than the torque curve of a petrol engine? And some other as well so if there are questions or doubt which you still have please let me know and also do comment whether this post helped you or not with our understanding of torque and horsepower.
