I honestly dont undersatnd or for that matter know what the big difference between torque and horsepower is.
A towing regular(like me) always thought that the more horsepower you have the better tow vehicle you have, but it seems that that isnt true, its seem to be all about the torque.
What is horsepower for?
What is torque for?

Why do they say that a v10 w/4.30 gears can do the same as a diesel w/3.73 gears as far as towing goes?

why do people say diesel is better than a v10 or vice versa whan they are rated to pull the same load?
PLEASE NO DIESEL VS V10 ARGUMENT, I AM JUST SEARCHING FOR THE TRUTH.

I personally have a Excursion v10 w/4.30s and pull a 773 bobcat and a mini excavator with attachments on the same trailer at the same time with a pintle hitch and i have not had a single problem. Im guessing that all together my equipment weighs about 14000 lbs total with trailer

Im not dumb, just a little slow

 

hp is how fast it can do the work
torque is what does the work
diesels have major low end torque which is what you want for towing.

 

I may be wrong, but I think of it as follows:

Imagine walking the stairs to your office in a 20 story building:

If you are climbing stairs, torque is how much weight you can load on your back and still climb. Taking the stairs in my building (with fixed step length and fixed leg length)I would run out of strength (torque) with 200 lbs on my back. Some other guy would have more torque or less torque than I have. [Torque is how much of a mule you are. Mules pull harder than thoroughbreds.]

Horsepower would be how fast I can climb the stairs, say with the 200 lbs on my back. Or I might have a different rate of climbing with 100 lbs on my back, so my horsepower would vary with different weights. If I were perfect, I could make it up the 20 flights of stairs in 2 minutes no matter how much weight was on my back. [HP is how fast you are runniing considering that you weigh 1500 lbs or so like a thoroughbred.]

Take the stairs at work a few times (like I do) and it gives you time to think about torque and HP. I think I calculated I have to generate 1/3 hp to get my fat **** up the stairs in 3 minutes (or some such time)

 

Thats a pretty good example

 

Here is a good article to explain the differences.

http://www.off-road.com/hummer/tech/power.html

Hope this helps.
Darren

 

Horsepower is what matters in moving a load at a given rate of speed. Increasing the rate of speed or the weight of the load requires additional horsepower. Given the same horsepower..... as the weight increases the speed decreases (or as the weight goes down the speed increases).

The only advantage diesels have over gassers is that they develop more horsepower a lower rpm's (as a result of higher torque). However you can do wonders with gearing.

We have a yard truck with a 5.9L TD that will pull around 100,000 GCW. Now it's top speed is only 15 MPH under full load but that is what you can do with gearing. Our yard truck has the same torque and horsepower of a 1 ton truck that can travel 70MPH with a 13,000# 5 th wheel but it is geared much lower.

So the horepower torque fights are like saying the Eagles are better than Philadelphia.....you can do so much more with the right gearing.

Regards,

Mike

 

HP and torque are the same thing, HP can not be measured. Years ago a dude named Watt, yes like the 100 watt bulb same guy, wanted to know how much work his mules were doing in comparison to equipment so he came up with a formula. You can look it up but no biggie. Torque can be measured so if we measure torque so to get HP take torque X RPM / 5252 = HP.
So as RPM's rise the motors torque # will go down but it's HP # will rise, a high reving motor will make more HP because of the revs but by design will not make much torque. A torque motor will have a long stroke so if you try to rev it piston velosity will become critical so it can not make big HP #'s.

So in order to understand a motor we are given both figures. In other words if I tell you a motor makes 500 lb/ft of torque and 100 HP you know right off this motor will not rev and there for not be usable. If I tell you a motor has 100 ft/lb torque but 1000 hp this motor might be ok in a Formula race car but be worthless on the street. So you se by giving both #'s it is only to paint a whole picture of how the motor performs. Torque is what you measure (OK rolling dyno's measure rate of change and you calculate HP and torque) but HP can not really be measured and in fact means nothing, it is mathmaticaly tied to torque.
Sumation a V10 say makes 415 ft/lb torque and 365 hp and a PSD makes 500 ft/lb and 200 hp you know right away the PSD will not rev as high. (#'s for explanation not meant to be correct) Look at the 7.3 VS the 6.0 and you will see the HP #'s for the 6.0 are higher because it revs more, part of the reason for going to a smaller motor was to get the revs so you could make a more balanced motor.

 

HP = (torque * RPM) / 5252.

Torque is twisting force typically measured in ft*lb or N*m and HP is a measure of how much twisting force is applied in a unit of time.

Good old James Watt (the steam engine guy) figured that a strong mill horse could lift 33,000 lb per minute or 550 lb per second. Given that we want to measure what is coming out of the end of a crank shaft that rotates, we divide 2 time Pi (6.28) in to the 33,000 lb to come up with the 5252 number.

At 5252 RPM, HP and torque will be equal. Less than that torque will be greater than HP and above that the HP value will be larger.

There are a couple good sites out there that go in to nice detail:
http://vettenet.org/torquehp.html
http://auto.howstuffworks.com/horsepower1.htm
http://homepage.mac.com/matt.kramer/...%20Torque.html
http://www.revsearch.com/dynamometer...orsepower.html

Enjoy,

Daryl

 

That is a great explanation.

 

Thanks,

And to be clear and to sync up with what I posted in the SD forum, the 5252 number isn't precisely 5252. I just rounded down to the nearest whole number. in the post, readers can see that the 33,000 was divided by 2 x Pi. And we know that Pi is a transcendental number that goes on forever.

So dividing a whole number by a transcendental gives you a transcendental.

Just wanted to be clear on that. So it's really 5252.11312203255......

 

Thanks for the further clarifications, but how does "twisting force over time" help us understand why torque and horsepower are a good thing? (Further how does clarifying 5252 to 10 sig. digits help us?)

Describing torque as "twisting force over a unit of time" is like describing acceleration by saying "it's velocity over a unit of time." Velocity is what determines how fast the stripes in the road go by. Acceleration (velocity over a unit of time) is what snaps your head back (or forward when you stop). Everybody knows that, but such explanations of HP and Torque would help this forum.

I think the best explanation of HP and Torque may be using a pulley hooked to the crankshaft. If I weigh 560 pounds, can the 6.0 lift me? Not if the pulley has a radius greater than 1 foot. (likewise, if I weigh 230, the 6.0 won't lift me if the pulley has a radius greater than 2 feet.)

So if it the 6.0 lifts me (at 230 pounds on a two foot radius pulley), how fast can it lift me? This is determined by Horsepower. The horsepower determines how many RPMS your engine will do in this loaded situation. The 6.0 characteristics dictate it will turn 3048 times per minute. That is the best it can do, and I'd be pulled pretty rapidly on that pulley. If we hooked up a horse with (one HP) and 560 pounds of torque, a two foot pulley would turn at 9 RPM, which would take me forever to be pulled up.

Engines without much torque would have to be geared to lift me at "highway speeds." Gearing multiplies peak torque to the wheels to any amount desired. Increasing the ratio increases torque.

I hope that is correct. I'm still trying to understand these things myself.

 

I know what you mean It can take a fair bit of head scratching to come to grips with what force, power, work, and all that really mean. Top that off with the fact that most of us are crippled with using U.S. Customary units rather than SI and when you start talking about mass, weight, force, and all, it is sometimes easier to just use SI to do the calc and then convert back to U.S. at the end.