I see many diesel trucks spewing black soot...

[supton]

Originally Posted By: KrisZ
Originally Posted By: Jarlaxle
As long as it is geared correctly, it will pull it.


And a gearbox is what? A torque multiplier. Sure, you can gear an F1 engine to pull the same load as the 6.7 diesel, but aside from the dismal fuel economy, it would blow up to pieces in short order.
HP matters if you plan on racing while pulling a trailer.


Even the diesel engines use a transmission with underdrive gears pushing a final drive which is under-drive also. All of which multiplies torque. I guess even diesel can't do the job right.

Horsepower is a measurement of how fast work gets done. Torque is a measurement of applied force. Technically I can generate piles of torque, standing on a 6' bar attempting to turn a bolt that is welded. Won't mean I do any appreciable work.

 

[Jetronic]

Originally Posted By: Shannow
Originally Posted By: Jarlaxle
Originally Posted By: Ramblejam
Originally Posted By: Jarlaxle
No, it really doesn't...repeat after me: one horsepower equals one horsepower! This is junior-high-school stuff.


It's your contention that in a F-550, the 6.8L gas (362 hp @ 4750, 457 lb-ft @ 3250) will out tow the 6.7L diesel (300 hp @ 2800, 660 lb-ft @ 1600)?


If the V10 truck is geared correctly, absolutely yes. Again, one horsepower equals one horsepower.


Yep...you are right.


question is, how long can the truck continue to deliver 362 hp? that's a lot of heat to get rid off, and a gas truck will produce more than a diesel for the same output. Also, you can't get 362 bhp from standstill to get the load moving.

 

[Shannow]

Originally Posted By: Jetronic
question is, how long can the truck continue to deliver 362 hp? that's a lot of heat to get rid off, and a gas truck will produce more than a diesel for the same output. Also, you can't get 362 bhp from standstill to get the load moving.


That's not part of the "power/torque" discussion, but still valid...how are the two things designed, built, and assembled (hint 620 versus 1,100lb).

 

[Shannow]

Originally Posted By: Ramblejam
Originally Posted By: Jarlaxle
This is junior high school stuff!

We'll agree on that. Most were able to eschew such flawed, theoretical belief when they left grade school; this is no different than the kids who would tell me that I could remove the Maxidyne from a R-model, drop in a high-horsepower Chevy V8, and with the right gearing, it'd run off and leave the old diesel behind. Of course, anyone with a scintilla of real-world, practical application understanding/knowledge would see past that foolishness in a second...we're not drag-racing here, we're towing heavy loads.

Based on advertised horsepower, one might mistakenly believe that the gas would perform better than the diesel. However, the speed at which horsepower occurs and torque dictates the engine's real-world performance.

6.8L Gas:
362 hp @ 4750
457 lb-ft @ 3250

6.7 Diesel:
300 hp @ 2800
660 lb-ft @ 1600

The gas engine here delivers maximum power at higher engine speeds, and those speeds are beyond normal operation range.


I think that your highschool wants their diploma back.

Is there a world that you consider the diesel is going to sit at 2,800RPM ALL day in "normal operation either ?

Put either in a vehcle fitted with an infinitely variable CVT, and both will "drag" or tow the same amount/time sitting at peak power...power is torque times RPM, so they are interchangeable.

Per jetronic's argument above, yes, the diesel will likely pull for a lot longer in service...it's built twice as heavy to do so.

 

[Ramblejam]

You want to play the silly game of theoretical, make-believe with products that don't exist. As I already said, I'm discussing "real-world, practical application".

Originally Posted By: Shannow
Put either in a vehcle fitted with an infinitely variable CVT, and both will "drag" or tow the same amount/time sitting at peak power...power is torque times RPM, so they are interchangeable.


We know. This has already been covered

Originally Posted By: Anduril
Oh, look at all those people lining up to pull trailers with their Honda S2000. 240 horses... at 9,000 rpm! Must be a fun experience!


Please keep up.

 

[Ramblejam]

Originally Posted By: Jarlaxle
Originally Posted By: Ramblejam
Originally Posted By: Jarlaxle
No, it really doesn't...repeat after me: one horsepower equals one horsepower! This is junior-high-school stuff.


It's your contention that in a F-550, the 6.8L gas (362 hp @ 4750, 457 lb-ft @ 3250) will out tow the 6.7L diesel (300 hp @ 2800, 660 lb-ft @ 1600)?


If the V10 truck is geared correctly, absolutely yes. Again, one horsepower equals one horsepower.

Jarlaxle,

Sorry for coming off short earlier; I can understand if you don't want to listen to me, nor DoubleWasp, or even the tow ratings that Ford provides. Instead of posting and just replying to nonsense from others (which is again why I've gone to helping over PM...), I took a few moments this evening to pull up some real-world, third-party test results so you have some good data to run with.

The F-250 here is powered by the 6.8L V10 (gas) making 362hp @ 4,750-rpm
The F-350 here is powered by the 6.4L V8 (diesel) making 350hp @ 3,000-rpm
Additionally, you'll notice that the gas truck has 4.30 gears, while the diesel has 3.73; this gives it the best possible gearing advantage for this model.

This testing was conducted with only 10,500#. As aforementioned by myself, with this kind of weight, the gas truck does a perfectly fine job, and it's why I like them (such as pulling a Jeep, as we discussed). However, as the loads get heavy (simulated by the 15% grade), and horsepower or not, the Diesel really pulls away.

 

[Jarlaxle]

Originally Posted By: KrisZ
Originally Posted By: Jarlaxle
As long as it is geared correctly, it will pull it.


And a gearbox is what? A torque multiplier. Sure, you can gear an F1 engine to pull the same load as the 6.7 diesel, but aside from the dismal fuel economy, it would blow up to pieces in short order.
HP matters if you plan on racing while pulling a trailer.


By that "logic", you should tow with a Poppin' Johnny!

Real-world experience...driving OTR, my uncle used two very similar tractors with two very different engines. One was an 855ci Cummins with gigantic torque, able to take off in high range (13-speed) even with one loaded trailer. The other was a 6-71T Detroit, about half the displacement of the Cummins; a low-torque, high-revving engine happiest when screaming against its 2300RPM governor. However, since both had proper gearing and the same horsepower, when pulling turnpike doubles, they both pulled grades at exactly the same speed!

 

[jcwit]

I thought we were discussing "Rollin Coal".

 

[KrisZ]

A transmission is nothing more than a lever, it just multiplies or divides the rotational force, a.k.a. torque instead of linear force. All this talk that torque doesn't matter, only HP and proper gearing is simply silly. Archimedes said "Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.". While theoretically true, it is impossible in practice. The same thing applies to engines with little torque. The transmission can make up for lack of torque, but only to a certain point, after that such a transmission makes no practical sense.

Again, a transmission multiplies or divides torque, not power, nothing more, nothing less. If the multiplication or division is not needed it is simply a dead weight. That is why electric cars do not have one. Their ability to provide full torque right from 0 RPM eliminates the need for the transmission.

Now, if you want to talk how fast a given amount of load can be moved, that's where the power comes in. However, since our roads and highways have speed limits, there is no need to chase HP, aside from marketing purposes. That is why all of the HD pick ups have anything between 300-400hp. This amount of power ensures that whatever the payload rating of the vehicle, it will be able to reach the speed limit and maintain it in a safe manner and in moderate grades.

If you want to pull a load in the fastest way possible, a.k.a. racing, that's where you start chasing power, however you still need to be able to provide enough torque to move it in the first place.

 

[demarpaint]

Originally Posted By: Ramblejam

I choose modern gas as well for these appplications, and you're lucky to have an excellent source of rock-bottom price, minimum rust trucks in your very state out on Long Island; however, our choice doesn't change the facts from above.


Rock bottom prices on Long Island, where? I live here nothing is rock bottom priced. We have our fair share of rust buckets, the roads are salted all the time, and people living near the coast have even more rust problems.

As far as your diesel vs. gas comments, they're spot on.

 

[supton]

Originally Posted By: jcwit
I thought we were discussing "Rollin Coal".


Most internet debates closely resemble rollin' coal, and accomplish about as much.

 

[supton]

Originally Posted By: Ramblejam
Originally Posted By: Jarlaxle
Originally Posted By: Ramblejam
Originally Posted By: Jarlaxle
No, it really doesn't...repeat after me: one horsepower equals one horsepower! This is junior-high-school stuff.


It's your contention that in a F-550, the 6.8L gas (362 hp @ 4750, 457 lb-ft @ 3250) will out tow the 6.7L diesel (300 hp @ 2800, 660 lb-ft @ 1600)?


If the V10 truck is geared correctly, absolutely yes. Again, one horsepower equals one horsepower.

Jarlaxle,

Sorry for coming off short earlier; I can understand if you don't want to listen to me, nor DoubleWasp, or even the tow ratings that Ford provides. Instead of posting and just replying to nonsense from others (which is again why I've gone to helping over PM...), I took a few moments this evening to pull up some real-world, third-party test results so you have some good data to run with.

The F-250 here is powered by the 6.8L V10 (gas) making 362hp @ 4,750-rpm
The F-350 here is powered by the 6.4L V8 (diesel) making 350hp @ 3,000-rpm
Additionally, you'll notice that the gas truck has 4.30 gears, while the diesel has 3.73; this gives it the best possible gearing advantage for this model.

This testing was conducted with only 10,500#. As aforementioned by myself, with this kind of weight, the gas truck does a perfectly fine job, and it's why I like them (such as pulling a Jeep, as we discussed). However, as the loads get heavy (simulated by the 15% grade), and horsepower or not, the Diesel really pulls away.


Interesting. Where is this data from? Not that I'm doubting it, I'm just unclear why a hp isn't a hp. Was this a standing-start acceleration?

450m is almost 1,500 feet, or more than a quarter mile; 250m is 820 feet. I'd think accelerating >15,000lb up 7% grade would take more than 30 seconds so I don't think it's a standing-start.

 

[SwampSurvivor]

I'm not saying that gas is better than , or equivalent to a diesel for towing in a light duty application.

What I'm saying is - for most light duty application - the gas is the better choice for most. For no other reason than they are cheaper to operate even with increased fuel cost.

I'm sure great uncle Arnold can pull every hill on the Interstates at 65 with his diesel truck and fifth wheel camper where a gas engine would slow down a bit and have single digit mileage. But the maintenance on a diesel is going to be much higher and repairs are out of this world.

I'd gladly sacrifice some fuel costs and speed on the hills.

 

[Srt20]

Originally Posted By: Shannow
Originally Posted By: Ramblejam
Originally Posted By: Jarlaxle
This is junior high school stuff!

We'll agree on that. Most were able to eschew such flawed, theoretical belief when they left grade school; this is no different than the kids who would tell me that I could remove the Maxidyne from a R-model, drop in a high-horsepower Chevy V8, and with the right gearing, it'd run off and leave the old diesel behind. Of course, anyone with a scintilla of real-world, practical application understanding/knowledge would see past that foolishness in a second...we're not drag-racing here, we're towing heavy loads.

Based on advertised horsepower, one might mistakenly believe that the gas would perform better than the diesel. However, the speed at which horsepower occurs and torque dictates the engine's real-world performance.

6.8L Gas:
362 hp @ 4750
457 lb-ft @ 3250

6.7 Diesel:
300 hp @ 2800
660 lb-ft @ 1600

The gas engine here delivers maximum power at higher engine speeds, and those speeds are beyond normal operation range.


I think that your highschool wants their diploma back.

Is there a world that you consider the diesel is going to sit at 2,800RPM ALL day in "normal operation either ?

Put either in a vehcle fitted with an infinitely variable CVT, and both will "drag" or tow the same amount/time sitting at peak power...power is torque times RPM, so they are interchangeable.

Per jetronic's argument above, yes, the diesel will likely pull for a lot longer in service...it's built twice as heavy to do so.

Diesels in boats and ships, spin at max speed all day long everyday. Just saying....

I don't get into the gas vs diesel debates. They each have their own uses for different people.

 

[The motor guy]

A lot of it can be because they're putin around town for a long time and then they get on it hard to pass somebody and the extra exhaust flow blows out the carbon build up inside the exhaust pipe.

 

[Anduril]

Originally Posted By: Srt20
Diesels in boats and ships, spin at max speed all day long everyday. Just saying....

Which is measured in the hundreds of RPM, not thousands.

 

[Ramblejam]

Originally Posted By: Srt20
Diesels in boats and ships, spin at max speed all day long everyday. Just saying....

Heavy Duty (HD), Medium Continous (MCD), Intermittent Duty (INT), and High Output (HO) do not. The only marine engines doing this carry a continuous duty rating (CON).

For reference - High Output 6.7L Cummins makes 542hp and runs 3300RPM; continuous 6.7L Cummins makes 301hp and is limited to 2600RPM

 

[Jarlaxle]

Which is about the RPM it runs in commercial service. (Highway RPMs are 2100-2500, with a 28-2900RPM governor.)