# Why does horsepower and torque meet at 5250

### Torque and HP Curves. What happens at RPM? - Pelican Parts Forums

Torque Vs. Horsepower. Have you ever wondered why “torque vs. horsepower” has always drawn so much debate? I think it's because since the definitions. Jason Fenske at Engineering Explained details why hp and torque people at parties if the sort of parties you go to are attended strictly by car. This article explains how torque and horsepower are related, and exposes some of the So, what does this mean to me when the rubber meets the road? Myth 3: A well-tuned engine is has equal torque and horsepower at about RPM.

With work it applies to distance moved feet and force applied lbsand with torque it applies to force applied lbs and lever-arm length feet.

Power is a measure of work and speed combined. The amount of power is not only related to the force applied and the distance moved, but also the speed at which the work is being applied.

You can think of it as a combination of rate and work. The bed is two feet high, and you lift six fifty-pound rocks in one minute. You have now loaded your pickup using. In the second case, however, it required twice as much power with the same amount of torque. This is because the torque was occurring at a higher rate of speed. This will generate a horsepower curve by calculating the horsepower at various RPMs. Find the peak of this curve the highest horsepower numberand that is the horsepower rating of the engine.

Depending upon the torque curve of the motor, maximum horsepower may occur at low or high RPM. Generally it is near the maximum RPM of the engine. So, what does this mean to me when the rubber meets the road? You have two rigs, one a diesel with ft-lbs of torque at RPM. You have another gasoline-engined rig that generates ft-lbs at RPM, which is also horsepower.

So, it can go up the hill at 70 MPH too, with half the torque of the diesel.

## Why does HP and TQ always cross at 5250 rpm on a Dyno ?

The difference is in the gearing of the rigs. The diesel-rig probably has overall gearing like 2. Even though the torque of the engines are vastly different, after compensating for the gear ratios of the differential and transmission, the torque at the rear axle is the same. After correcting the gearing to operate within the operating RPMs of each engine, the lesser torque of the higher-speed engine is multiplied to be the same.

However, not all engines of the same peak horsepower are completely equal. For example, the horsepower curve may be flatter as a percentage of RPM on one engine than the other. While both may be exactly the same performance at peak horsepower, the engine with a flatter horsepower curve may give better performance because when you shift from gear to gear you have higher average horsepower.

• Debunking Horsepower and Torque Myths

An example of a peaky motor might be one with horsepower at its peak RPM ofbut it only has at and RPM. For best acceleration, you should shift at redline or max torque or max horsepower or None of these are exactly true, but redline is probably the closest guess of the three. You could derive a fancy equation involving the integral of the area under the horsepower curve between the RPM points of the two gears at the shifting speed, but as a practical matter you want to go past the peak horsepower RPM, then shift when the horsepower in the present gear decreases to be equal to the horsepower of the RPM after you shift to the new gear.

In many cases this may be near redline, but not always. It depends on what gear you are in and how many RPM are lost when you shift. Consequently, you should shift at so that after the shift you are going -- the same amount of RPM above peak as below peak horsepower. In this case the average RPM is roughly equal to the peak horsepower. This assumes that the shape of the horsepower curve is about the same on both sides of the peak, and while not exactly correct, is pretty close in most cases.

A well-tuned engine is has equal torque and horsepower at about RPM. Torque and engine rpm were observed and recorded.

## Why do horsepower and torque cross at 5,252 rpm?

Click here for a description of how this happens on our dyno. On modern day dynamometers horsepower is a calculated value. It's important to remember the dyno measures torque and rpm and then from these calculates horsepower. On the dyno it takes more water flow to the water brake to increase the load on the engine being tested.

As the test engine's torque rises more water flow is needed.

### RevSearch Engine Dyno; Torque vs Horsepower

As the test engine's torque drops less water flow is needed. The dyno's water brake does not respond to Horsepower. Major adjustments to water flow are needed as an engine crosses its torque peak but none are needed as it crosses its horsepower peak. In other words the water flow to the brake during a dyno test follows the engines torque curve and not its horsepower curve. Torque is what twists the tire, prop, or pump.

Horsepower helps us understand an amount or quantity of torque. We will use Watts observation of one horsepower as pounds, feet in one minute. First we need express pounds of force as foot pounds torque.

Horsepower vs Torque - Explained

Pretend the force of pounds is "applied" tangentially to a one foot radius circle. This would be foot pounds torque. Next we need to express feet in one minute as RPM. The circumference of a one foot radius circle is 6. We are then talking about pounds of force foot pounds torque35 RPM, and one horsepower. RPM Divide both sides by ft. At rpm the horsepower and torque numbers will be exactly the same. I've been told it also involves something called "radians".

See a definition of radians in the comments link below I am not an engineer so my explanation may not be technically correct with out using "radians".

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