The psd cannot go 65 in third. Not even at 4000 rpm Which there is no torque availabe at 4000 rpm. The cummins will win in this more realistic, more apllicable test. We can assume that either is not carrying gods weight to move at 65mph. Probably nearto max gcvwr. It has less rpms but better gearing and torque. In this imaginary test.

http://cvt.com.sapo.pt/performances/performances.htm
Gearing is only advantageous if there is a set gear.
http://www.v8914.com/Horsepower-v-torque.htm

 

Okay, so still if the Ford downshifts to 4th, which is 1 to 1 then it will have an advantage over the Dodge that remains in 4th, which is an overdrive gear.

 

PSD/TS vs DODGE/CUMMINS at 65mph

A Ford PSD/Auto-TS and a Dodge/Cummins/5600 are driving across the salt-flats. They each have an empty trailer into which we are going to add weights until someone must downshift to maintain speed. They both must maintain the same ground speed. The first forced to slow down loses the race. We will start with the Dodge going at 65 mph. Each has a 3.73 rear axle and 31inch diameter tires.

My assumptions for this analysis include the following:

FORD:
I’m using the published PSD torque/HP curve from the PSD brochure, adjusted upward 10 ft-lbs for their new 570 ft-lb 2005 PSD, with the exception that I smooth that back into no extra torque gain at the 325HP point. For the Duramax, I am using their published max Torque/HP as shown below, and I assume a drop-off distance of 450 rpm after peak HP, which is identical to the curve shape for the PSD. In review:

PSD:
2100 rpm = 570 ft-lb
3300 rpm = 325 HP (518 ft-lb)
3750 rpm = drop off to zero
Slope of the Ford torque line from 2100 rpm to 3300 rpm is y = 657 - 0.041x

Torqshift Gears
1st: 3.09
2nd: 2.20
3rd: 1.538
4th: 1.00
5th: 0.712

Dodge Cummins
1600 rpm = 590 ft-lb
2900 rpm = 325 HP (588 ft-lb)
3350 rpm = drop off to zero (assumed based on peak horsepower at 400 rpm less than PSD)
Slope of the Dodge torque line from 1600 rpm to 2900 rpm is y = 614 - 0.0092x

NV5600 Gears
1st: 5.63
2nd: 3.38
3rd: 2.04
4th: 1.39
5th: 1.00
6th: 0.73

(1) DROP IN THE FIRST LOAD (1,068 ft-lb-rev/min): Ford/PSD must downshift to 4th

Dodge Engine RPM at 65 mph is:
RPM = ((Speed * 0.73 * 3.73) / (3.14 * 31inches) * 1056
RPM = (65mph * .73 * 3.73 * 1056) / (3.14 * 31 inches)
RPM = 1920 RPM

Cummins work potential is 596 ft-lb x 1920 rpm = 1,144K ft-lb-rev/min
Transmission axle rpm = 1920/ .73 = 2630 rpm.
Ford must go transmission axle of 2630 rpm, so engine turns 2630 * .712 (5th gear) = 1873 rpm
Torque @ 1873 rpm = 560 ft-lbs
Work potential of the Ford = 560 ft-lb x 1873 rpm = 1,068K ft-lb-rev/min).
The Cummins has more torque reserve (1,144K ft-lb-rev/min to 1,049 ft-lb-rev/min).
We drop a load in each trailer equal to 1,049K ft-lbs-rev/min of load.
The Ford must downshift and maintain transmission axle rpm = 2630 rpm
4th gear is 1.0 so engine is going 2630 rpm. Torque @ 2630 rpm = 549 ft-lbs.
Work capacity = 2630 rpm x 549 ft-lb = 1,444K ft-lbs-rev/min.

(2) 2nd DROP OF MORE LOAD (1,444 ft-lb-rev/min): Dodge/Cummins must downshift to 4th

Now the Ford has more torque reserve (1,444 to 1,049 ft-lbs-rev/min).
We drop more load in the trailer and the load is upped to 1,049K ft-lbs-rev/min.
The Dodge/Cummins must downshift and maintain transmission axle rpm = 2630 rpm
4th gear is 1.0, so engine is going 2630 rpm. Torque @ 2630 = 589 ft-lbs.
Work capacity = 2630 rpm x 589 ft-lb = 1,549K ft-lb-rev/min

(3) 3rd DROP OF MORE LOAD (1,549 ft-lb-rev/min): Ford must downshift to 3rd

Now Dodge/Cummins has more torque reserve (1,549 to 1,444 ft-lbs-rev/min)
We drop more load in the trailer and the load is upped to 1,444K ft-lb-rev/min
The Ford must downshift and maintain transmission axle rpm = 2630rpm
3rd gear is 1.538, so engine is going 2630 rpm x 1.538 = 4044 rpm.
REDLINE. Cannot maintain that engine rpm… the truck is forced to slow down to a slower transmission axle speed, and go slower with the new load of 1,444 ft-lbs-rev/min in the trailer. So what should the Ford/PSD slow down too? Well, if the max RPM for the dodge is about 3750 rpm, then 1,444 ft-lb-rev/min divided by 3750 rpm means it would need a torque of 385 ft-lbs. Can a Ford/PSD produce that amount there? We’ll assume so. The new speed of the Ford will now be:

Speed (mph) = (3750 RPM x 3.14 x 31 inch tires) / (1.538 x 3.73 x 1056) = 60 mph

Congratulations to Heretic. You found the sweet spot starting point for the Dodge. Notice the PSD doesn't lag far behind.

Marine Ironman

 

No they have very similar performance because of identical hp. But each will be stronger in certain situations. The PSD obviously faster.

If you do auto vs auto you will find the same sweet spot. It is because of where the gear lands the engine tho. There is no trick. Just its geared to do well at that specific speed. Same as the PSD will kick the cummins butt at 75mph. 65 seems like a more reasonable speed to travel at if you are loaded very heavily though.

Glad to see the larger brakes. For towing safety. An exhaust brake is an extra life insurance policy. Ive never had brake fade while towing because I do so very responsibly and with a manual. I have had brake fade in a little car without a load and I left a permanent clench mark on the seat. Not fun. Driving is an interesting task. A little forethought goes a long way. Planning ahead can be life or death. Analyzing traffic patterns ahead can be life or death.

One of my first jobs was delivering motor homes from one side of town to the other. I was one of two employees who didnt damage a motorhome during my tenure. One day I am crossing town in the rain in an older chevy motorhome with vacuum boost brakes. The fords were better they were air assist. In the chevy you had to brake with both feet. Otherwise you could not exert enough pressure to stop in time.
This young woman sees a parking spot and decides to pull in front of me and take the spot. Unfortunately there was not much distance to the spot so she cut me off and stopped rapidly. Roads are wet and I am going to have a difficult time stopping. I was able to stop without locking up my brakes. If I had locked em up. I would have creamed her. A motorhome will make a mess out of a little car. I wonder if she knew that she couldve lost her life that day. After which I made it a point to drive the fords.

 

OK, Marine Ironman, do you have more than one user ID now?

 

At least for this thread I do. The Book Burning club has decided I bash Dodge too much. The Dodge ladies won. That's okay. John-diesel you've been a very nice guy. I've imparted enough knowledge into the forum, so that other smart-thinking guys can pick up the ball and run with it, including yourself. My photos gone, my signature destroyed, my login neutered. Just had to haunt the place to see who was doing what.

Farewell John

 

Ironman. I have strong views but I do not bash. No names no bashing and your ok. Sorry you got booted. But you have to keep it clean.

 

oh, and goodbye Heretic. enjoyed it. I was hoping you'd see the "hole between the gears" and you nailed it, good job. if Dispenser shows again, tell him farewell.

Col William "Ironman" Lee, signing off.

 

Sorry to see you go. I had a good time. I hope we can debate again. Or it wont be no fun round here no more.
Its all about having a good time and taking some new knowledge home with you. I dont take any of it very seriously. I dont even own either one of these trucks. So im just a couch expert.
I would love to tow with both of them to get a feel for their strengths and weaknesses. I just dont like the idea of an 800 dollar a month truck payment right now. Specially when I own mine.
The ford is definitely a much nicer truck. All the way around. Dodges quality problems put it out of the picture until they can prove to me that they have their act together. Couldnt convince me to buy an oversquare diesel. So no duramax in my future.

 

No matter if you like the debate or not it is important to remember the Guidelines are for all, even people who have lived their life by a code.....and should understand and respect the rules without question.

 

No bigsnag. The comparison was with both in direct drive.

The cummins is at peak hp around 65mph in direct drive. The PSD peak is at 74mph in direct drive. Thats rpms at work for you. Who woulda thought that a measley 400 rpms would be 9 mph in direct drive. Both engines can operate above peak hp but if they encounter a large load they will be pulled down to this rpm. Because of the exponential effect of air resistance it would be possible to pull them down into the low 60s but then they could maintain the speed. Air is one of your worst enemies towing. 48mph is peak hp for the PSD in third. So it could probably pull 52 mph maybe a smidge more. So much torque is availabe at the wheels that it can go past peak hp. Even with a very heavy load. Worst case scenario puts the PSD at 52mph. Thats with the biggest baddest load and the biggest baddest hill you can find. I cannot forsee anything that would pull it lower. Not any legal load or paved road.

It would definitely have the advantage over the cummins in this case. The PSD would have a 2 or 3 mph advantage. It would be more but the dodge auto has a slightly taller second gear.

 

Let's clear a few things up.

His albums where not touched.

His signature was not removed.

His login was not turned off.

Only his access to this one section was turned off.

His views on Dodge didn't come into play. He was locked out of this section for taunting those who disagreed with him by telling them they smoked pot. The section guidelines are very clear that this section is for technical discussion only and "Emotional threads, flame wars and trolls will not be tolerated."

This second registration of this user to get around the section ban has resulted in his termination from the site. Its a shame someone in the US Marines can't follow a few basic rules, I'm glad this doesn't represent the majority of them, especially officers.

 

Unfortunate.

With this new info. I went and looked up the test again. All these figures have been for 4.11s and the pickuptruck . com test was with 3.73s. So this fudges the numbers a little.
At the end of the quarter mile on the 7% with a 12k load. The PSD was still in third.
It looks like its just about to the end of fourth in the flat land quarter mile test while empty. And just shifted to fourth at the end of the quarter with a 12k load on flat land. This is max acceleration tests. Gives you an idea of where the engine will be in the gears at the end of 1250 and 1700 ft respectively w/ and w/o a load.
This is just for reference but this is the fastest time so its obviously in a good gear for the load. These tests are done from a dead stop. To me thats not totally indicative of how they will perform on the great wide open. Each has a load and an rpm where it will eat the other for breakfast. But the PSD will always win a race.

 

This is getting too emotional for me to continue to read--I can't stand it any longer!!!!!!

 

So PSD wins?