False.

You clearly ignored RPM's. Torque is not what creates a sub 6 second run, because torque is stationary. Torque is still sitting at the line waiting for something to happen, while the person in the next lane won the race because they allowed their engine to spin RPM's.


Wrong again.

Literally your sentence said: increase RPM's in order to create more horsepower in order to create more torque. That is absolutely NOT the way power is created.

Total power output in horsepower is what pulls trailers, moves vehicles, gets you up a hill, etc. To reach horsepower, you have to have torque AND RPM's. More RPM's doesn't create more torque. RPM's doesn't create anything. It's a measure of time.

Still wrong.

Torque has NOTHING to do with acceleration. Why? Because torque is STATIONARY. Torque isn't moving. Look at the formula for torque and tell me where there is movement in that calculation. Weird because acceleration is movement. What has movement? Horsepower of course.

Are there differences in efficiency? Of course, and I've mentioned that time and time again. An engine that has very low torque output and spins at much higher RPM's to make the same horsepower as a motor that puts out that horsepower at much lower RPM's will not be as efficient in fuel. No one here is arguing that. What you keep doing is confusing torque with horsepower and interchanging them as if they were one and the same. They are not. Acknowledge that they are different, then educate yourself as to why they are different. Then step back and apply them correctly to see how your arguments in this thread have been severely flawed.

 

Your breaking it down into nonsense and my major point has nothing to do with fuel mileage. You will never get a 800 HP Nascar to accelerate like a Pro Mod and it's not the lack of HP but the lack of torque, You need 2000 FT pounds of torque to accelerate and 800 HP to go 250MPH for Sub 6 seconds in a 2500 hundred pound package for a 1/4 mile run. RPM is just what the motor does multiply x torque to get the HP. Who cares how he gets it and at what RPM.

You don't have to make it complicated.

Who cares where the torque is and in what part of the power band as long as you have it you can gear to keep the motor in the peak torque zone of the RPM output for maximum pull.

A Top Fuel car does not even have a gearbox because it makes so much torque it can pull 2300 pounds to 350 in a 1/4 from torque generated without one.

All they are doing is loading the motor in the RPM range where it makes maximum torque with the clutch by applying it harder and harder at a rate of grab to hold it in the max torque output RPM range where ever that is probably about 5000 or 6000 RPM so they can get down there as fast as possible. They change that rate of engagement to adjust amount of TQ HP meeting the pavement depending on track traction because a Fuel car can just boil the tires to the rim all the way down the track it makes so much torque and HP.

They say a TF car in power is equivalent to 2 locomotives but again 2 locomotives are about 50,000 ft pounds of torque and a TF car is 1/8 that so it cannot get a big train up to speed without a shove from some other external force to help it generate the power it is capable of making when wound up to accelerate thousands of tons to desired MPH speed.

It has the HP but not the torque, this is just the same thing but a slightly bigger scenario compared to the RC motor in a moped example I gave earlier.

It's real simple to understand and you need no complex formulas.

This is the thing, what is on paper is correct but you may not understand what that means until you see it in action in use in real world application. When TJC told me a 600 HP rig could accelerate a load of 80 grand up a step grade I was like a 600 HP car cannot do that at all so what was the other part of the equation and it was torque. That is when I finally understood how to read a Dyno and what it meant.

 

The real world answer to your question;
I had a 7,000 boat that I pulled with an '05 Chevy Suburban Z-71 4X4.
The truck was fine at pulling low speeds (295 Hp) but because of the sail area of the boat all it was capable of on the interstate was 65 mph on flat ground.
I replaced the sub with an '02 F-250 CC, LB 4X4, 7.3 (275 Hp), around town it is about the same, on the highway it will pull at any speed you care to drive.
The diesel just pulls much better even though it is much heavier.
I now have a boat that weighs 10K, the F-250 will pull it as fast as you care to drive and gets better mileage than the sub did pulling the smaller boat.
The F-250 just pulls like a train.

LA

 

Thanks I appreciate it, I learned a lot. For heavy pulling higher torque lower RPM motors just work much much better Gas or diesel. I understand why now.

 

I'm not making it complicated. I'm pointing out that you are completely and totally wrong.

You started a thread asking for help explaining how it works, and when the correct answer is given, you ignore it and continue arguing.

Look at your above statement: "You need 2000 FT pounds of torque to accelerate". WRONG! You need HORSEPOWER to accelerate. Why? Because acceleration is work. Horsepower is the measure of the actual work being done. Torque does NOT measure the work. Get it now?

And let's look at this statement: "Who cares how he gets it and at what RPM". Wrong again! RPM's are precisely the factor. I've explained this several times in this thread already. You can take an engine with LESS torque output and have it make MORE horsepower if it's capable of higher RPM's than another engine with MORE torque output. Now take those engines and have them pull a trailer uphill, or drag race side by side. The engine that produces MORE overall horsepower the entire time will always win. Period. There is no argument against that.

Wrong again! You clearly ignored my other post where I gave this example:

To further study, which will win a towing race up a mountain pass...
- 7.3L Powerstroke running at peak torque of 525 lb-ft @ 1,600 RPM's?
- 6.2L Ford Boss engine running at peak torque of 434 lb-ft @ 4,500 RPM's?

At 1,600 RPM's, the Powerstroke has 160 horsepower.
At 4,500 RPM's, the Gasser has 372 horsepower.

The 6.2L gas engine will win the race up the mountain if each engine maintains the RPM's to keep it at it's peak torque output. The reason is that the amount of work being produced by the 6.2L is more than twice that of the Powerstroke. So even though the Powerstroke has more torque, the mechanical work being done is limited by RPM's.

The lesson here: Torque does not equal power. If you look only at torque, you are ignoring RPM's.

Clearly the gasser wins, even though both motors are doing EXACTLY what you stated.

Makes ZERO sense. Comparing apples to squirrels without even properly using horsepower and torque.

That's a completely backwards statement. Formulas are designed to explain events mathematically.

Really? Then take my example of the 7.3L, put it on cruise control and keep RPM's at 1,600. I'll take the gasser and run it at 4,500 RPM's and we'll see it in action as I pull away all day long. That's real world. You ignore facts when they aren't convenient.

600 hp is 600 hp. A car can't do it because it can't physically hook up to a trailer in the first place.

But if you had a gas motor that made 600 hp and put it in a semi, then yes it will tow a load of 80 grand up a steep grade. It's not the torque that is pulling the load, it's the horsepower. The torque is only going to determine where in the RPM band you will be towing in the first place. If both motors can maintain their peak 600hp the entire pull, then both will end up reaching the top of the climb at the exact same time.


You started this thread asking for help. Now you're biting the hands that are feeding you information. Stop and take a minute to think about what you are posting.

 

No realslow, you don't understand why. But I can explain Lattitude's results.

This is where people get confused between "on paper" and "real world".

Both the 7.3L and the Chevy make close to the same horsepower. However, if you put both vehicles on the dyno and look at their power band, you will see that the Chevy motor has a quicker peak and fall off, where the 7.3L has a more steady and even horsepower curve.

What does this mean? It means that the 7.3L is capable of staying at or near peak horsepower for more of the driving scenario. This is why the 7.3L will out pull that Suburban.

Now go back to that 6.2L motor I used in the example. The 6.2L still makes less torque overall than the 7.3L, but makes FAR more horsepower. Put the 6.2L on the dyno and it's power band is wider than the Suburban, so now you have more horsepower to work with in a broader RPM range. Go ahead and hook the two up side by side in this same scenario, and the 6.2L will out pull the 7.3L all day long. It will run circles around it. The 7.3L will still get the better fuel economy, but it won't keep up in acceleration and speed.

Horsepower wins the pulling and acceleration contests. If your dyno curve has a broader horsepower range, meaning it stays at or near a higher horsepower for a longer period of time than another compared engine, then it will out pull and out accelerate regardless of the fuel being used.

And that is how to explain what happens "on paper" and what happens in the "real world". Torque won't do anything if you can't turn it into motion. The instant that happens it becomes horsepower. Because horsepower is torque in motion.

 

Pocket,
What would the comparison be between a 6.2 gas and a 6.7 diesel.
The horsepower is closer between these two engines versus the 7.3 in the posts above

LA

 

The 6.7L will out pull hands down. Again it goes back to that power curve. Even though both engines have similar peak horsepower, the 6.7L has a broader horsepower band than the 6.2L.

Here's how to break it down, I'm using hypothetical numbers not actual 6.7L or 6.2L dyno results.

Let's say both motors have a peak of 400hp. The diesel can maintain 300+ horsepower from 1800-3200 RPM. That's 1,400 RPM's of power band over 300 hp, and you tow up a mountain staying ONLY in that power band as you change speed and gears. Now the gasser can maintain 300+ horsepower from 4,000-5,200 RPM. That's 200 RPM's less power band than the diesel at over 300 hp. Furthermore, while towing up the same mountain you spend time outside that power band, going anywhere from 2,000-6,000 RPM as you change speeds and gears. That's time spent under 300 hp, while the diesel never drops below that power range.

So the engine that spends the most time at the highest horsepower wins the race. That's why the 6.7L out pulls the 6.2L. That's why the 6.2L out pulls the 7.3L. A diesel can out pull a gasser and vice versa. It all depends on how much available power you have and how it's used. Torque all by itself doesn't doesn't do anything.

 

Here is a scenario to prove what I am saying in my mind and real world and I own both and it shoots a hole in what you are saying. Honda CR 500 and a Honda CRF 450 for hill climbing. They make the same HP 55 RWHP one is a 2 smoke Diesel truck and the other a 4 stroke spinner. The 4 stroke makes way way broader power over the RPM range and makes peak output at about 8 or 9 grand. The CR 500 makes max output at 5500 and I mean narrow power band.

You can go on the net and read dyno pulls on both machines and you will see where the CRF 450 has a way broader power band over a much wider RPM but peak HP is all more so upstairs and then you can pull up hill climbing on Utube and watch the CRF450 get it's a$$ handed to it on the steep hills by the CR 500. As a matter of fact this motor a CR 500 is a threat at hill climbs to win because it has this nasty narrow Knot of torque the hill shooters know how to utilize. Much narrower power curve but because it makes way more torque earlier and the crank has more torque if held in proper RPM range to spin up to maintain the relatively low HP no matter how you gear it and for this reason even today the engine is highly sought after. The CRF is much easier to overload even though it has a much broader power band. I do believe you are missing part of the equation which is for pulling their is no substitute for peak torque because you can always clutch and gear it to over come a broader power spread if you have more torque to maintain your HP under load.

Look on flat land putting along in 5th gear on my CR500 I can role the throttle on and with no clutch the bike will immediately power out and role up to a 100 MPH with nor problem. Why do I have to down shift on the CRF450 even though it has a much broader power curve and make the same HP? because the CR 500 has the power down low like a diesel. This is on flat land and as the incline gets steeper the CRF 450 will have a harder time under the load to spin up to make the HP until it can't and overloads and chokes out and the CR 500 just motors away no matter how geared to compensate.


This is what you are seeing and as stated earlier people do not understand what the dyno is telling them, they look at it like a bunch of #'s and really do not get it. Their is no substitute for peak torque at the crank when under load and the more the load the more it becomes apparent the spinner does not have the raw power the non spinner does no matter the power curve and gearing the motor that makes more peak torque can out pull the one down on torque, gearing does play a role but apples for apples YOU NEED TORQUE TO PULL GOOD because you cannot spin up to HP under heavy load if you do not have it no matter how broad your power curve .

 

Actually it doesn't shoot a hole in anything as I've already clearly described this scenario in my other posts. I've highlighted in bold and explained below once again.


Your comparison clearly takes one engine out of it's peak HP range while leaving another in it's peak HP range. As I have stated over and over and over and over again in this thread..... if you keep both motors of identical HP at that peak HP, they will both do the exact same work and pull exactly the same speed.


But your example takes one trying to spin up to a much higher RPM in order to make the same peak HP as the other motor that doesn't have to spin nearly as fast. Yet again, I gave examples of this happening in the real world, and explained why. It's very clear that one is spending more time outside of the peak power band than the other, which will lend the motor that stays in the peak power band the longest as the clear winner. This I've already described in detail in my other posts. You just aren't reading and comprehending this.

It's obvious you didn't start this thread to learn anything. It's also obvious you aren't trying to even read and understand my posts. Maybe someone else can come in and explain it to you, but I'm tired of going in circles.

 

I understand your post completely and learned from them but what I am saying is the motor that makes more torque will pull a load better if geared correctly HP being equal no matter how broad the curve is of the one that makes HP further up the RPM power band this is gearing dependent however. I agree with you and what I learned was RPM is feet per second and that explained alot.

The torque motor will have a much easier time making the HP and keeping it as the load goes up because it makes more torque. The lower torque motor is more easily over loaded and HP scrubbed under a heavy load, maybe I am missing something.

 

I went back over this and finally read the whole thing, I was just spouting off because I thought I understood HP but I realize now I did not understand it as well as I thought and Pocket helped a lot in making it make more sense so in the future I understand it much better so Thanks.

But I think he is looking at a piece of paper and missing something in the equation and that is the torque motor makes the HP much much easier through Raw grunt rather than spinning up more and getting it through more RPM.

I don't think a Nascar is going to pull a Tractor trailer well at all "sorry Pocket" no matter how you gear it, I am going to talk to a builder to settle this and yes HP is HP but you have got to be able to make it under a load and that is where I think the torquer gets the spinner big time.

 

The answer to the original post is what type of power do gas vs diesel engines produce at the speeds that we tow at.
Most trucks (both gas and diesel) now days are in the 1800 - 2200 rpm range at 70 mph.
At those rpms, the diesel has the best torque and horsepower.
Under load it will almost always outperform gas, the greater the load, the more apparent the difference.
If you look at the power curves at that rpm range it is pretty obvious for towing you want your peak torque and HP in the lower rpm range where you operate.
Again this is at the rpms to run at the speed limit while towing, drag racing is not in this equation.

LA

 

I just had to throw a bunch of spaghetti up against the wall and sift through it and it worked good for me to learn, I did not mean to offend anybody and if I did sorry. For the most part so far Pocket is right so thanks. I was just trying to understand it in my head before I looked everybody's replies over to see where I got it wrong.

I will understand this whole thing shortly, I just read where people use a formula and say you can do it through gearing and I read people saying it does not work like they say on paper on this forum and you need diesel to pull heavy and they buy a diesel and never look back also I read what a 240 HP semi does with a 5speed and I am like no 240 Hp car motor will do that no matter how geared but he's right HP is HP but I worded my approach wrong and it is how you make the HP by spinning a lot of RPM or Low RPM torque and the dyno shop I talked to so far said a 600 HP car engine will run a tractor trailer with many more gears than the standard rig set up so like 50 plus gears and that was what I was saying as well, the gearing is unrealistic. I just want to understand why these motors behave how they do is all.

I will talk to a few more people and everybody thanks for all the good replies.

 

I talked to 2 engine builders and a dyno company and got mixed opinions about this and I want to talk to a few more.

I just want to understand how HP works and how it applies to the real world. The 2 engine builders said I was right in understanding how to read a dyno and what it meant.
The paper printout on a dyno tells you what the motor can do and what it can't but people think you can gear to make what you want if each engine produces the similar HP and RPM output ranges are totally different and the motor builders say no THE TORQUE# is way way more important for pulling or most racing. So they were in agreement that people cannot understand what the dyno tells them.

Everybody posting said their diesels pull way better in this thread so I just want to know why for real world sakes. I just about got it figured out real close so thanks for all the help from everybody.