The Definitive Torque vs. Horsepower post

holstein13 wrote:

Therefore, if you have any room for acceleration, that means you are not producing your maximum horse power. Mathematically, you will only achieve your maximum horsepower at maximum torque times maximum RPM and that almost always happens in top gear (unless you are climbing a mountain)

Another way to think about this, is that you will only achieve your maximum horsepower when you are burning fuel the quickest.

You can produce max hp and accelerate.

Max hp does NOT have to be max tq times max rpm... Like I showed you earlier my max torque is 610, my max rpm is 2900. Using your max torque time max rpms I would end up with 336.8hp but it only makes 325.

The math can go both ways, hp and tq are nearly always rated at different rpms. That's how my max hp is only making 588 ft/lbs even thou it's at my peak rpms before defuel.

Torque/5252*rpms = hp.

So mathematically your statement is incorrect, hp and tq are mathematically related but the peaks occur at different rpms on nearly every engine.

It also RARELY ever happens in top gear, simply based on top speed vs speed limits, tire limits, speed limiters, etc... Diesels are one of the few vehicles that can hit rated rpm in top gear on a highway and not be doing unsafe speeds. My truck tops out at 102 with the current tires before it begins to defuel.

You can do this in lower gears by putting your foot on the floor, it's the most common way to achieve max hp. You might only make that peak hp for a small time as the rpms go thru the rated rpms or a shift occurs. But I bet there is only a small percentage of owners that have ever hit peak hp in top gear, but anyone who has ever held their foot on the floor thru redline has made their engines peak hp. Gears have nothing to do with it (torque management aside), it's about rpms and fuel.

You don't have to load an engine to the point of ceasing acceleration to make peak power.