So here we have two identical vehicles. The only difference between them is that one makes 1000 horsepower and 500 pound feet of torque and the other makes 500 horsepower and 1000 pound feet of torque. The question is: If we these two vehicles faced each other on a quarter mile drag course, which one would win? Horsepower or torque?
Well that’s the question we will answer today and by answering it we will gain a more profound understanding of horsepower torque and vehicle dynamics and possibly also a headache. So let’s get started
Now these numbers are peak torque and peak horsepower numbers but before we use them we need to know at what engine rpm do these peak numbers occur. To make things fair we will say that peak horsepower and peak torque occurs at the same rpm for both vehicles. So let’s just say that peak horsepower occurs at 5000 rpm and let’s say that peak torque occurs at 2500 rpm.
Now if you already know a bit about torque and horsepower you might be able to tell that there’s something wrong with one of our engines. And to demonstrate the issue as well as our first lesson of this video I will use this convenient little formula and it says that horsepower is equal to torque times rpm divided by 5252. The same formula for metric units would be Kilowatts equal torque in Nm times rpm divided by 9549, but I’ll be using imperial units today because later in the video we’ll be plugging numbers into a simulation software that’s programmed in imperial units. But the lessons and concepts explored in this video are completely independent from and are equally valid whether you use metric or imperial.
Now we’re going to learn something about horsepower and torque by demonstrating how our horsepower biased engine is actually impossible. We will then fix this engine to make our drag race fair and possible.
Let’s say that we want to find out what kind of torque this engine generates at peak horsepower rpm which is as we said 5000. So according to our formula 1000 = x times 5000 / 5252. If we solve for X This gives us 1050.4 pound feet of torque. Which is higher than our peak torque of 500. Things don’t add up. As you can see from our simple formula horsepower is torque times rpm divided by a constant, so horsepower is essentially torque times rpm. In other words horsepower within itself contains both the amount of torque and the frequency of torque application. In the simplest terms possible: horsepower is torque over time where time is represented by rpm, rotations per minute.
So if we are achieving 1000 horsepower at 5000 rpm than our peak torque simply cannot be 500 pound feet. And that’s because horsepower is a product of both torque value and frequency of its application. If both torque and the frequency of it’s application is high then horsepower will of course also be high. It is impossible to have high horsepower with very low torque. The only way to achieve that is to make up for the low torque with a very high frequency of torque application, or very high rpm. If you can’t punch very hard then you have to deliver more punches im the same period of time to deliver the same amount of damage.
In our case we have a high horsepower figure, 1000 at a relatively low rpm, 5000, and this tells us our torque must be high. In other words we’re dealing a lot of damage with a relatively low number of punches and this tells us that each of our punches definitely packs a punch. This teaches us how torque, horsepower and rpm are inter-connected. It is incorrect and misleading to try and observe and compare them isolated from each other.
So if we want to have a 1000 horsepower and 500 pound feet of torque engine then peak horsepower cannot be delivered at 5000 rpm. If we want to do the same damage but keep our punches weak then we must increase the number of punches delivered.
A special thank you to my patrons:
Daniel
Pepe
Brian Alvarez
Peter Della Flora
Dave Westwood
Joe C
Zwoa Meda Beda
Toma Marini
Cole Philips
#d4a #horsepower #torque
00:00 Explanation
05:40 Simulation
11:56 Results