"The cummins with the auto has better torque at the wheels and hp on tap at cruising speed. It is geared to tow more weight. More comfortably at 65mph. It has more hp on tap at that rpm and more torque at the wheels. This makes it slower in a race too."

Makes it slower?? Dude, you might want to go back and read that again. I guess LESS hp on tap and LESS torque at the wheels makes something FASTER in a race?????(SNIP)????????????

 

IRONMAN: The Dodge manual at 2900 engine rpm and the Ford PSD at 3300 engine rpm. Each is at 325 HP. But that means each is at a different road speed.

IRONMAN: No. Impossible. If they both go 90, the Cummins will be at a lower HP. They can both go that speed, but if you start dropping weight in the back, the Cummins will have less HP ... and eventually come off that speed due to maxing out it's work potential (peak torque for that RPM times that RPM).

IRONMAN: Actually, no. Here's why ... in that scenario I laid out, I know the speed Dodge is going at 1600 mph. The Dodge engineers made that point (max torque) to equal the 55 mph highway speed. Here's the double check:

On my Excursion, going the same speed of 2192 tranxaxle rpm, it was 1560 engine rpm. okay ...

Speed (in mph) = (RPM x 3.14 x Tire diameter in inches) divided by (0.712 5th gear x 3.73 rear end x 1056 conversion for mph and inchs/hr)

my tires are 31 inches across

Speed = (1560 x 3.14 x 31) / (0.712 x 3.73 x 1056)
Speed = 54.14 mph

SO ... the scenario I laid out is going EXACTLY at normal highway speed of ~55mph. Look how the Cummins and PSD did. The Cummins eventually loses it at highway speed, and the PSD keeps chugging at 55 mph with a heavier load.

In my opinion ... then ... the PSD is better geared for Mom-n-Pop highway heavy-RV towing ... or Billy Bub towing his horse-trailer to the show.

I'm not sure what the Cummins is better at, I haven't figured it out yet. But I know you won't have to downshift first, if you hit a hill, that's about it. Dodge needs to go get themselves a V8 diesel engine for their light trucks. The more I think about it ... the more JohnsDiesel is right. The Cummins is in the wrong truck. It'd be better, for example, to drive one of those Parking-Lot busses at the Airport. Heavy weight ... low speed driving all day.

Mr. Ironman

 

This is only confusing because of the RPM thing. He didn't say racing he said 65 mph only... no accelerating... get it? The PSD does put out less torque at 2900 rpm and under, and less hp at 2700 rpm and under. This is why the Cummins is putting out more hp and torque at cruising speed on flat highway. When the PSD is putting out the SAME amount of torque it is travelling down the road at a higher speed(assuming they are in the same gear) and then WALA! the PSD has another WHOLE gear to use up as well. Therefore it can travel down the road at a higher overall speed(unless it is governed) etc. etc.

RECAP- if the Cummins and the PSD are going the same speed... the Cummins is laying down more hp and torque in most situations. If they are laying down similar amounts of hp and torque... the PSD is going faster since its ideal torque rpm is higher... get it now bigsnag?

 

I've got to get a better life guys. Like MI says they sit around all day dreaming up different scenarios.....I have read one of the recent tests that floored the trucks at a certain speed(50?) and recorded the g force of acceleration for each. I can't even remember if dodge or chevy was second but the ford was first. However what I did wonder was 1)what gear did the truck go into and how close to its maximum hp was each truck going when the test was done. 2)How long after flooring it did they take the measurement 3)Could each truckmaker picking the speed at which the truck was floored and how long after to take measurements taken affect the outcome?(turbo spoolup, gearing differences, etc.). I imagine that probably would happen if they were all allowed to create those criteria. Imagine reading one article saying ford has more acceleration, has this many g's and here's what they had. Nother mag does the same with dodge and chevy of course gets in the act. They would probably all be able to do it just because of the gearing and power differences of the different makes.


I can't stay here as my time is more valuable. I volunteer several hundred hours a year toward the hs band and work about 55hrs a week. It has made for some real short rest periods and its got to stop. I really enjoyed the discussions and have learned a little about figuring torques and hp and stuff. I don't really need the extreme power that is the subject here, but I know the feeling of having something that is better than the next. I also know its not always reality but perceived reality. Good luck with the posts. Could soon be a record. No offense to anyone, if I did offend please accept my apology.

 

Ok guys, there is a test out that compares the 04 PSD/TS against 04 1/2 Cummins600/6 speed. I won't spoil it but I 'll put it this way even with the Ford loaded it out ran the Dodge empty.

Also there is an article for the 05SD. Torque has increased 10lbs and now is the highest rated truck in payload and towing capability.

P.S. Look at this months Truck Trend.

 

Once the load is up to cruising speeds it really doesn't matter as much. So now you are clinging to a new strage idea, that the two trucks will instantly be moving 60 MPH and never encounter situations, such as an incline, where they need to downshift or slow down (traffic light). The PSD will get the load up the hill faster and will get it up to crusing speed faster. At 60 MPH my engine performs equally with the Cummins and 6.0 PSD because all are capable of maintaining a steady speed. For that matter, the 5.4L V8 will also equally perform. I think you're really grasping here.

Next issues:
Cummins has advantage in 0-0 MPH time
Cummins maintains 0 MPH with more power than the PSD
Cummins accelerates faster in the owner's mind
Cummins maintains more power in the owner's mind
Cummins accelerates faster into a parking space
Cummins maintains the parking space with more power than the PSD
Cummins logo adds more torque to rear wheels when towing


Can't
Understand
Most
Meaningful
Information
Needed
Sometimes

 

The big picture is putting power to the ground. Flywheel numbers dont do you any good if you cant put the power to the ground..They sound nice but mean nothing.

 

Well if you notice I did address the stop light scenario in a sense when I said the Cummins accelerates faster from 0-40 with or without similar loads especially on hills. So THEN when you get to the highway and are going 60 mph, we'll just say 60 since were towing a trailer weighing 12,500 lbs... I like to be a little safe even if bigsnag feels he can stop in time going 90 with 20,000 lbs. on his back. The Cummins is laying down more torque and hp... yay since thats the only thing I can grasp onto while the PSD blows my doors off... because whatever makes it faster is the only thing that matters.

When Ironman started talking about God throwing weight onto the trucks... I said okay... unlikely that God would suddenly do that after a couple thousand years of hiatus or that you would meet a 15% grade of paved road that holds its steepness for a mile; but alright... I'll let it go. Just let it go man... just another dumb comparison.

P.S. I really liked the Next Issues part, thanks for the laugh I needed it.

 

Mr. Spencer, you've graduated from boot camp and are now a Horsepower Marine. Hand salute, fair winds and following seas.

Mr. Ironman Lee

 

Do you have a link to that? That scenario is very similar to my analysis (that PSD would haul more and beat the cummins)

 

Its not online yet, you can buy it at the store though.

I will say this once more, With the Ford loaded, it still had better times, 0-40, 40-60 and 0-60 than the Dodge empty.

Thanks for playing.

P.S. Oh ya its not even close.

 

You're cracking me up. I have to admit, we've really run the Cummins down through the mud and back. But the PSD simply outshines even w/ 560 torque. It's amazing. What many folks have not yet picked up on ... even in this thread ... is that the V8 brings some inherent strength to the table. It's a relatively new industry ... and Ford is going down the right path of the future for light-truck diesels. It may get to a point that the PSD V design, if beefed up to a 7 or 8 liter, could really take the medium truck market. I'd love to see the Business Planning room at Navistar/International.

Ironman

 

I think the game is over. They have no chips left but refuse to leave the table.

 

Well, after giving it some thought, the Cummins doesn't prevail in all these cases.

PSD wins the 0-0 MPH time because it's in a Ford. The Dodge owner has to fill the failing transmission with fluid before he climbs into the driver's seat.

PSD maintains 0 MPH better because the driver doesn't feel compelled to jump out and pretend it's not their truck.

The Cummins does indeed win in the Cummins' owner's minds. I'll give you those 2.

The Cummins accelerates faster into the parking space, but the PSD is already parked.

The PSD maintains the parking space better because it's heavier. People are also more careful not to open their doors into the Ford because, well, it isn't a Dodge.

Unfortunately for the Cummins, the PSD logo adds power over a longer period of time.

 

Ok. Do the math with the auto. I was only making a point about the manual. I have let it go. Lets compare autos. Thats what Ive been doing in the last few posts. With the auto. The cummins has more torque at the wheels and more hp on tap at 2000 rpm which is about 65mph for both. Highway speeds.

If you have 325hp. Geared to travel at a lower speed. 50 compared to 75. You have more torque at the wheels at 50 and can tow more weight. Your still making the same hp.. You arent going as fast but can be loaded much heavier. An engineer told me that 325hp is 325hp doesnt matter where you make it. At 5000 in a gasser or 2500 in a diesel. They will do the same work. The gasser will accelerate faster but it cannot tow more.

The best way to increase your ft lbs per minute would be to go to a 3.55 rear gear right. That way you could tow WAY MORE. Less faster does not always equal more. In this case it just equals the same.

Inline 6s bring some inherent strengths to the table too. Better fuel economy. Better durability and reliability. Better low end torque. If these things are not of concern. Then a v8 is better.
I meant what if I geared em to both go 90 at their peak hp. Would one be making more power? The point is. You can acheive the same results if you just change the gearing. The reason they perform different is because of the gearing. The PSD will get up there faster but will have a harder time holding its gear. Its a tradeoff. We both agree the PSD gives up its gear easier. If the PSD drops into fourth because it cannot hold fifth. The Cummins will be traveling faster. Auto vs auto. See the tradeoff. If its more likely to drop a gear. Its also more likely to go slower up the hill. The max wheel rpms if you like are 1022 cummins 804 PSD. I get 94mph for the cummins and 74mph for the PSD. With dirty math. Not that anyone would want to go that fast. When it comes to holding its gear, which translates to going faster, and putting torque to the ground the cummins with the auto does it better at highway speeds. All figures are with the autos and a 4.11 rear differential.

I get 65 mph at peak hp if the cummins drops into direct drive. With 325 hp. I cannot see it dropping below 65mph with anything short of a 20k trailer behind. Putting it well past it ratings. MI. Do you have the math to compute hp and speed against climbing grades? I had it one time. The math was. A 325hp diesel pickup would have no problem climbing a 6% grade at gross at 65 mph. Assuming some kind of aerodynamic trailer. I wanted to double check my figures.

Do you get where Im headed MI. 325 vs 325. If one is faster the other is stronger. It one is stronger the other is faster. I am pretty sure they could gear the PSD to be slower but tow more weight. Not that they would want to but it could be done. Just like the could gear the cummins to be faster at an expense of driveability with a trailer.

They have never sold the cummins cause it was the fastest. 1 million people bought the slowest diesel on the market. It made less hp and came in a dodge. Why in the world would someone do something so foolish? The crazy thing is some of em do it over and over. Ive read of some guys on their third or fourth slow diesel. Incredible the way some people think. They could buy the fastest diesel on the market and its a reliable v8 too. With a great reputation for having zero issues.