2014 Jaguar F-Type: Smartly-Integrated Tech And Almost 500 Hp

[nuvon]

"Grandmastersesay". Higher torque gives you higher acceleration, not horsepower. Horsepower gives you how fast you can go, in other words top speed. As you go faster, the amount of torque reduce and the amount of horsepower increase,

 

[vertexx]

Just wanted to point out that the discussion on torque and hp, it's easy to find a solution by looking at real world.

The answer is not torque or HP, HP is just used to describe the work that can be done. The answer is actually the formula itself describes the potential speed of the car, factor in weight. The formula itself is the answer but who is going to explain that to people, it's just much easier to say a higher HP car is generally faster than a lower HP car.

Unbelievable this won't die......

The acceleration of a car is simply this: A = Tw/(Rw*M), where A = Acceleration, Tw = Torque at the wheel axle, Rw = Radius of the Wheel, and M = Mass of the car. This is of course ignoring mechanical friction, wind friction, and potential tire slippage. It is easily derived from the first equation anyone learns about acceleration, F=MA, where Torque/Radius is substituted in for Force. You don't see Power in this equation - this is the formula for Acceleration, period. If you want instantaneous acceleration, look at torque applied at an instant. If you want acceleration over time, look at torque over time.

Power is a derived property. You cannot measure power directly in ANY system. It is always derived from at least two measurements. In the case of a car, it is Torque and RPM. In the case of electrical power, it is Voltage and Current. Power does not tell you how much current will flow through a wire; voltage does.

Where Power is useful is it shows the capacity for doing work (hence it's definition = rate of doing work). So, we want to know an engine's general capability for pushing a car, power is useful. If an engine has a low Torque but high RPM, that Torque can be Amplified through a transmission by reducing the RPM. Energy is conserved but Torque increases as RPM decreases. It is the same as a transformer in an electrical circuit. You trade voltage for current but power stays constant (neglecting losses of course).

This whole sidetracked discussion started when one guy basically told another guy he was a complete idiot for saying Torque > Power, when his attack started out on the right track but then ended with a bunch of completely false statements.

Power is derived from Torque and RPM. But Power does not accelerate a vehicle. Torque does. No matter how much power you have in the engine, you have to ultimately translate the power into torque at the wheel; otherwise you're going nowhere.

Really, Power came into popular use for Automobiles in the 70's - 80's primarily driven by marketing. In the 60's and early 70's engines were always sold based on Torque. However, as engines were getting smaller, it was not good marketing to have this year's model have less torque than last year's. At the same time, RPMs were increasing. This made the transition to marketing engines based on power much more attractive.

This is not to imply that power is not an important property of a vehicle, because it is. Just don't mistake what actually makes the vehicle move. For a high-end sports car on a track, you can use high RPMs reduced through a transmission to amplify your torque at the wheel. But for every-day driving, when you step on the gas, good low-end torque makes a car much more drive-able.

 

[Grandmastersexsay]

Just wanted to point out that the discussion on torque and hp, it's easy to find a solution by looking at real world.

The answer is not torque or HP, HP is just used to describe the work that can be done. The answer is actually the formula itself describes the potential speed of the car, factor in weight. The formula itself is the answer but who is going to explain that to people, it's just much easier to say a higher HP car is generally faster than a lower HP car.

Unbelievable this won't die......

The acceleration of a car is simply this: A = Tw/(Rw*M), where A = Acceleration, Tw = Torque at the wheel axle, Rw = Radius of the Wheel, and M = Mass of the car. This is of course ignoring mechanical friction, wind friction, and potential tire slippage. It is easily derived from the first equation anyone learns about acceleration, F=MA, where Torque/Radius is substituted in for Force. You don't see Power in this equation - this is the formula for Acceleration, period. If you want instantaneous acceleration, look at torque applied at an instant. If you want acceleration over time, look at torque over time.

Power is a derived property. You cannot measure power directly in ANY system. It is always derived from at least two measurements. In the case of a car, it is Torque and RPM. In the case of electrical power, it is Voltage and Current. Power does not tell you how much current will flow through a wire; voltage does.

Where Power is useful is it shows the capacity for doing work (hence it's definition = rate of doing work). So, we want to know an engine's general capability for pushing a car, power is useful. If an engine has a low Torque but high RPM, that Torque can be Amplified through a transmission by reducing the RPM. Energy is conserved but Torque increases as RPM decreases. It is the same as a transformer in an electrical circuit. You trade voltage for current but power stays constant (neglecting losses of course).

This whole sidetracked discussion started when one guy basically told another guy he was a complete idiot for saying Torque > Power, when his attack started out on the right track but then ended with a bunch of completely false statements.

Power is derived from Torque and RPM. But Power does not accelerate a vehicle. Torque does. No matter how much power you have in the engine, you have to ultimately translate the power into torque at the wheel; otherwise you're going nowhere.

Really, Power came into popular use for Automobiles in the 70's - 80's primarily driven by marketing. In the 60's and early 70's engines were always sold based on Torque. However, as engines were getting smaller, it was not good marketing to have this year's model have less torque than last year's. At the same time, RPMs were increasing. This made the transition to marketing engines based on power much more attractive.

This is not to imply that power is not an important property of a vehicle, because it is. Just don't mistake what actually makes the vehicle move. For a high-end sports car on a track, you can use high RPMs reduced through a transmission to amplify your torque at the wheel. But for every-day driving, when you step on the gas, good low-end torque makes a car much more drive-able.

You are just wrong.

You can not calculate how much a vehicle will accelerate in a given amount of time, or over a specific distance, with just force. The simple idea of applying that force for a period of time changes it from being force to being work, and power is the capacity to do work.

The force accelerates the vehicle, but you can't have the vehicle accelerate without doing work to it. Your way of thinking about it is overly simplistic.

If what you were saying were true, you would have the greatest acceleration when the engine is making peak torque, while in reality you have the greatest acceleration at the engines peak power. That should end the discussion right there. A vehicle has the greatest amount of acceleration at its peak power.

Go look at power curves. Torque almost always peaks well before power does. Horsepower = (Torque x RPM)/5252. Increasing RPM generates as much power as increasing torque. This is why top fuel dragster have close to a 10k RPM red line. They sacrifice torque to make more power, and all they care about is acceleration.

The only reason low end torque makes a car more drivable is because you then have more low end power.

I'll give you credit for at least thinking about it, unlike the rest these jabronis.

 

[vertexx]

You are just wrong.

Exactly which statement in any of my posts do you think is incorrect?

You can not calculate how much a vehicle will accelerate in a given amount of time, or over a specific distance, with just force.

I just did. Are you trying to tell Newton his equation is "Just wrong"? What equations are you using. Yes, you can actually calculate acceleration based on power, but only if you know the speed or RPM. You have to take the RPM or Speed out of the power in order to get acceleration. The equation for a car's acceleration based on Power is this: A = 375*Pe/(Speed*Mass), where Pe is power currently applied by the engine, and Speed is the vehicle speed in MPH. Notice that you need to take the speed component out of Power in order to get Acceleration. This is because Acceleration is caused by Force or Torque, not by Power.

The simple idea of applying that force for a period of time changes it from being force to being work, and power is the capacity to do work.

You are partially correct here. This is where you start to confuse yourself. You don't change force into work. Work is defined as force applied over a given distance. (Work = Force * Distance)
Power is defined as the rate of doing work (Work/Time).

The force accelerates the vehicle, but you can't have the vehicle accelerate without doing work to it. Your way of thinking about it is overly simplistic.

You are correct. Applying the force over a distance accelerates the vehicle AND performs work in doing so. Yes, I am simplifying it to the core element that causes acceleration. However, don't mistake my simplifying it for lack of knowledge on the subject.

If what you were saying were true, you would have the greatest acceleration when the engine is making peak torque, while in reality you have the greatest acceleration at the engines peak power. That should end the discussion right there. A vehicle has the greatest amount of acceleration at its peak power.

I have not talked about Engine Torque. I have talked about Torque at the Wheel. You are correct in that you obtain the greatest acceleration at the engine's peak power. However, this is because this power is translated to maximum Torque at the wheel by reducing the RPMs from the engine and amplifying Torque. Peak Torque at the wheel ultimately causes the maximum acceleration.

Go look at power curves. Torque almost always peaks well before power does. Horsepower = (Torque x RPM)/5252. Increasing RPM generates as much power as increasing torque.

Yes, this is true. Power increases as RPM increases. Torque does not. I've never disputed this.

This is why top fuel dragster have close to a 10k RPM red line. They sacrifice torque to make more power, and all they care about is acceleration.

You are correct that top fuel dragsters rev the engines up to 10k RPM. But that power needs to be translated to applied Torque at the wheel. Otherwise, they would not go anywhere. In fact, RELATIVELY speaking, top fuel dragster engines are optimized for maximum Torque - NOT RPM. Think about it. This reviewed F-type has a peak power of 495 HP at 6,500 RPM and a peak Torque of 460 lb-ft from 2,500-5,500RPM. A top fuel dragster engine has a peak power of ~8,000 HP, and Torque in excess of 5,000 lb-ft in the range of 8,000-10,000 RPM. So compared with the Jaguar, the dragster has only 50% more RPMs than the Jaguar but over 10 times (that's >1,000%) of the torque. It therefore obtains much more Power from it's Torque than from RPM compared with the Jaguar. For the other extreme, compare this to a Formula-1 engine, which has it's peak power of 755 HP at 22,000 RPM, with only 206 lb-ft of Torque, even less Torque than the Jaguar.

The dragster needs to Accelerate, and therefore is built for maximum Torque relative to other cars. The F-1 is optimized for top Speed relative to its Power, and therefore has the extremely high RPMs. Your own example proves my point.

The only reason low end torque makes a car more drivable is because you then have more low end power.

This is not correct. The reason low end torque makes a car more driveable is that you don't need to rev the engine up in order to use RPMs to jack-up your Torque at the wheel. You can get Torque applied at the wheel directly from Torque at the engine. Yes, that car will also happen to have more low-end power. But that is only because it has more low end Torque. I can't emphasize enough - Power is derived from Torque, not vice-versa.

I'll give you credit for at least thinking about it, unlike the rest these jabronis.

Dude, you really need to chill out. I have never said you were wrong in saying Power determines the overall capacity for doing work. What I have said is the Power is a derived property. You can't measure it. And you don't apply Power directly to anything in any system. Power needs to exercised in the form of some force or potential in order to get anything done. You were the one who jumped in somebody's shorts, saying that Torque has nothing to do with Acceleration, when it has everything to do with acceleration.

While I am relatively new to the PC enthusiast scene as a hobby I've adopted over the last year, on this subject, I happen to know what I'm talking about. My credentials on the subject include degrees in Applied Physics and Mechanical Engineering, a Master's degree in Systems Engineering, a former Nuclear Engineer in the U.S. Navy, and an entire career in electrical, mechanical and thermal systems engineering. So, I'm afraid that on this subject, you giving me credit is just plain ridiculous.

I'm here to learn on these forums. Perhaps you can learn a few things as well.

 

[Grandmastersexsay]

You are just wrong.

Exactly which statement in any of my posts do you think is incorrect?

You can not calculate how much a vehicle will accelerate in a given amount of time, or over a specific distance, with just force.

I just did. Are you trying to tell Newton his equation is "Just wrong"? What equations are you using. Yes, you can actually calculate acceleration based on power, but only if you know the speed or RPM. You have to take the RPM or Speed out of the power in order to get acceleration. The equation for a car's acceleration based on Power is this: A = 375*Pe/(Speed*Mass), where Pe is power currently applied by the engine, and Speed is the vehicle speed in MPH. Notice that you need to take the speed component out of Power in order to get Acceleration. This is because Acceleration is caused by Force or Torque, not by Power.

The simple idea of applying that force for a period of time changes it from being force to being work, and power is the capacity to do work.

You are partially correct here. This is where you start to confuse yourself. You don't change force into work. Work is defined as force applied over a given distance. (Work = Force * Distance)
Power is defined as the rate of doing work (Work/Time).

The force accelerates the vehicle, but you can't have the vehicle accelerate without doing work to it. Your way of thinking about it is overly simplistic.

You are correct. Applying the force over a distance accelerates the vehicle AND performs work in doing so. Yes, I am simplifying it to the core element that causes acceleration. However, don't mistake my simplifying it for lack of knowledge on the subject.

If what you were saying were true, you would have the greatest acceleration when the engine is making peak torque, while in reality you have the greatest acceleration at the engines peak power. That should end the discussion right there. A vehicle has the greatest amount of acceleration at its peak power.

I have not talked about Engine Torque. I have talked about Torque at the Wheel. You are correct in that you obtain the greatest acceleration at the engine's peak power. However, this is because this power is translated to maximum Torque at the wheel by reducing the RPMs from the engine and amplifying Torque. Peak Torque at the wheel ultimately causes the maximum acceleration.

Go look at power curves. Torque almost always peaks well before power does. Horsepower = (Torque x RPM)/5252. Increasing RPM generates as much power as increasing torque.

Yes, this is true. Power increases as RPM increases. Torque does not. I've never disputed this.

This is why top fuel dragster have close to a 10k RPM red line. They sacrifice torque to make more power, and all they care about is acceleration.

You are correct that top fuel dragsters rev the engines up to 10k RPM. But that power needs to be translated to applied Torque at the wheel. Otherwise, they would not go anywhere. In fact, RELATIVELY speaking, top fuel dragster engines are optimized for maximum Torque - NOT RPM. Think about it. This reviewed F-type has a peak power of 495 HP at 6,500 RPM and a peak Torque of 460 lb-ft from 2,500-5,500RPM. A top fuel dragster engine has a peak power of ~8,000 HP, and Torque in excess of 5,000 lb-ft in the range of 8,000-10,000 RPM. So compared with the Jaguar, the dragster has only 50% more RPMs than the Jaguar but over 10 times (that's >1,000%) of the torque. It therefore obtains much more Power from it's Torque than from RPM compared with the Jaguar. For the other extreme, compare this to a Formula-1 engine, which has it's peak power of 755 HP at 22,000 RPM, with only 206 lb-ft of Torque, even less Torque than the Jaguar.

The dragster needs to Accelerate, and therefore is built for maximum Torque relative to other cars. The F-1 is optimized for top Speed relative to its Power, and therefore has the extremely high RPMs. Your own example proves my point.

The only reason low end torque makes a car more drivable is because you then have more low end power.

This is not correct. The reason low end torque makes a car more driveable is that you don't need to rev the engine up in order to use RPMs to jack-up your Torque at the wheel. You can get Torque applied at the wheel directly from Torque at the engine. Yes, that car will also happen to have more low-end power. But that is only because it has more low end Torque. I can't emphasize enough - Power is derived from Torque, not vice-versa.

I'll give you credit for at least thinking about it, unlike the rest these jabronis.

Dude, you really need to chill out. I have never said you were wrong in saying Power determines the overall capacity for doing work. What I have said is the Power is a derived property. You can't measure it. And you don't apply Power directly to anything in any system. Power needs to exercised in the form of some force or potential in order to get anything done. You were the one who jumped in somebody's shorts, saying that Torque has nothing to do with Acceleration, when it has everything to do with acceleration.

While I am relatively new to the PC enthusiast scene as a hobby I've adopted over the last year, on this subject, I happen to know what I'm talking about. My credentials on the subject include degrees in Applied Physics and Mechanical Engineering, a Master's degree in Systems Engineering, a former Nuclear Engineer in the U.S. Navy, and an entire career in electrical, mechanical and thermal systems engineering. So, I'm afraid that on this subject, you giving me credit is just plain ridiculous.

I'm here to learn on these forums. Perhaps you can learn a few things as well.

Perhaps I was wrong. Perhaps you are just another jabroni.


We can talk about torque at the wheel, or torque at the engine. It doesn't matter, it is all the same. The transmission simply acts as a torque multiplier.

Perhaps an algebraic explanation will help you understand.

Let's say we wanted to accelerate a 100 lb object at 33 ft/s^2 for 10 seconds.

If you are not familiar with imperial units:
First, 1 slug ~ 33 lb (lb mass, not lb force)
100 lb ~ 3 slug

F = m*A = 3 slug * 33 ft/s^2 = 100 lbf/s^2 = 100 lb

Here is where you fail to understand what's going on. We need to accelerate for 10 seconds. In other words we will accelerate for a distance, which means we will be doing work(W=F*D), and we do that work in a certain amount of time.

So first we'll use our position formula to calculate the distance traveled.

D = (1/2) * A * t^2 = (1/2) * 33 ft/s^2 * 100 s^2 = 1650 ft

That means we are applying a force of 100 lb for a distance of 1650 ft over a span of 10 seconds.

(100 lb * 1650 ft) / 10 s = 16500 ft*lb/s

Interesting units aren't they. Kind of looks like the units for horsepower.

1 hp = 550 ft*lb/s

(6500 ft*lb/s)/(550 ft*lb/s) = 30 hp

So to accelerate 100 lb at 33 ft/s^2 for 10 seconds we would need 30 hp.

 

[vertexx]

So to accelerate 100 lb at 33 ft/s^2 for 10 seconds we would need 30 hp.

Absolutely correct. Everything in your last post is completely correct. Maybe you are learning something. Good.

The problem is you are now answering a different question. You're original statement was this:

Horsepower dictates your rate of acceleration, not torque.

This statement is false.

Just as you indicated here, Force (or Torque) dictates your acceleration: You need 100lbs of force to accelerate a 3 slug body at 33ft/s^2.

F = m*A = 3 slug * 33 ft/s^2 = 100 lbf/s^2 = 100 lb

So, let me hear that again, how much FORCE do you need to cause an ACCELERATION of 33ft/s^2? I don't care how much POWER you have, you need to apply 100 lbs of force to cause that acceleration. Yes.

Unfortunately, in your circular logic, you are now answering a completely different question:

So to accelerate 100 lb at 33 ft/s^2 for 10 seconds we would need 30 hp.

So now you're throwing in rate of doing work. So, duhh, yes, that is Power.

So, congratulations, you finally have a post with 100% accurate information. Just don't start talking yourself in circles again. Enjoy.....