You are mistaken. The psd does have its powerband at a higher rpm. But it does not have any more rpms IN the powerband than the cummins does. What the psd does have is more area under the curve. Great for racing but Im not buying that its great for driveability.

I looked up the definition of powerband cause I was curious. I then applied the definition against both engines. The answer was they have the same powerband. Just at different rpms. The cummins powerband begins 400rpms sooner and terminates 400 rpms sooner. The cummins also has a much flatter torque curve. So it maintains its power, in the powerband, slightly better. From 1500-3000 the cummins makes more hp, than the psd will, at the same rpm.

 

Thank you, I was wondering where you went. Stick around more chief.

Logical Heritic..."From 1500-3000 the cummins makes more hp, than the psd will, at the same rpm."

But to carry that further, Given the GSK's and fuel plates, a Cummins will have more HP and TQ at higher rpms than that. Is this maybe why there are no PSD Rail dragsters? And for one reason or another less psd sled pullers than even the duramax.

 

Hmm. My eyes beginneth to glazeth over All I know is that I don't drag race, or pull sleds. My truck works on the road (pavement) and sometimes off of it. Having driven both (friends' dodge, and my psd) I'll keep my psd. I don't know the numbers, and don't know how much power it pumps at what rpm, but I do know it pulls anything I've tossed at it, and pulls it well, and it seems to be a well-behaved engine. Maybe its my bias (was never fond of Cummins when I drove big-rigs, always preferred CAT or Detroit (series 60 is, in my opinion, the best engine Detroit put out), but either way, I prefer my psd.

 

AHH dodge guys on a ford site, sure cant blame them for trying to convince a ford guy something we already know (that are fords
are better). And i agree with nightbiker, over the road cummins
are gutless, except maybe on the flat, mine temp truck was. And
I also preferred my little cat in my truck. have more but i lost
track of what i was going to say.

 

I am a Ford guy. I just don't care for the Navistar engine that Ford bought to put in their truck. That's all.

I suppose if you compare a 91 Dodge/Cummins to a new PSD yeah the Cummins would be weak. The same would apply if I compared a 95 Ford/psd to an 05 Dodge Cummins, the Psd would be weak. 05 for 05, both are pretty close, but the power advantage still goes to Cummins, even if only by 40 ft lbs.

 

hmm...

Am curious, why do you state but the power advantage still goes to Cummins, even if only by 40 ft lbs.???
Yes it has more on paper torque, but the PSD's ability to make torque at higher rpms means it can drop down a gear (multiplying the torque to the wheels) much before a Cummins can.
So while the Cummins might have a higher torque figure, because the PSD is capable of producing torque at higher rpms, it is able to run greater gearing reduction at a given road speed, and hence the actual torque at the rear wheels will be greater.

 

If the PSD is downshifting a gear from overdrive it would be a direct drive(1:1). That's not multiplying any torque, you have to make sure the torque converter is unlocked for any multiplication, that's IF you have an automatic. If you need to downshift to beat a Cummins, maybe you need some more fuel and better turbo or 2 .

I think the thread started out as some Cummins exec. getting some kind of award. Not who can theoretically "urinate" farther. I'm not a moderator though.

 

No, its not multiplying any torque, but overdrive reduces the torque, so effectively more torque is being delivered to the wheels.

And yes, our little debate has gone on for a while hasn't it

 

BigF350. Do you subscribe to higher rpm torque for diesels? Im a bit of a purist. I was happy with peak hp at 2500 rpm. These engines are getting more performance but I think longevity is going to be seriously compromised. Why not spin a diesel to 5000 rpm? I can tell you if the cummins or psd made peak hp at 4500, I wouldnt buy one. But an engine that makes peak hp at 4500 would be faster. Faster isnt a concern for me.

 

Careful BigF350, your logic can be applied to all engines for arguements sake, not just a CTD or PSD. The CTD does make much more torque and HP throughout any reasonably useful RPM range than the PSD does. This isint an inline vs v8 issue either, it's all in the programming and fuel. The Powerstroke is programmed as a high revver.
More fuel and more wear to make the same HP and torque a Cummins makes just loafing along in overdrive at 70 on the highway.

By your logic a high revving hemi offers higher rpm power which means it can afford to downshift to second to windup and put as much torque to the rear wheels as the Cummins in overdrive, sure it's true, but it sure ain't near as efficient. Gearing is great for making torque at slow speeds, but can never replace actual engine torque at highway speeds.

 

Ok.
I will try to clarify my comments:
As a rule I do not subscribe to the higher rpm torque when it is at the complete loss of low rpm response and torque.

However, a Diesels nature is to have fantastic off idle torque and response, but (in general) to be less powerful than an equivelant gas engine at higher rpm's.

Now because I am greedy, I would like to save my cake and eat it too.
The likes of the V10 and 5.4 Gas motors now have more and more off idle torque, and a much linear power delivery, to make them behave more like a diesel, but keeping the traditional higher rpm power.
Now I want my diesel in my SD to be more like these engines in their power delivery, but with the diesel characteristics of improved fuel economy, greater reliability, and more torque throughout the rpm range.

Seeing that even if an engine is capable of 4500rpms, it will spend the majority of its time at 2000rpms or so (highway cruising speed and around peak torque) I do not believe that longevity will be compromised, and given that many diesel engines available here in Australia are capable of reving up to, or over 5000rpm (my diesel Ranger redlines at 5000, 5250rpm is its cutout), and I have seen many of these engines travel hundreds of thousands of miles without problems.
I think a much more major component of reliability is engine design and not its rpm cutout.

I don't neccessarily believe that fast is the best, but I believe that adequate power should be available at all time, if a user requires it (maintaining speeds up hills etc.), and providing adequate power is not at the loss of drivablity I think it is all fine.

 

Well a hp is a hp. If a truck had 325hp at 1800 rpm. It would be really driveable but not fast. So I guess its what you intend to use the truck for that matters. If you tow heavy then low rpm torque is king. If you want to race you want as many rpms as you can get. Vehicles with 10000 rpms are pretty quick. So I guess I want 800 lb ft at 1600 rpm. 250 hp, or so, would be plenty. If I want to race Ill buy a vette.

 

well my cummins goes down the road tacking around 1900 rpms at 65 mph 610 ft pds of torque and plenty of power and plenty of rpms to go.
also i liked the picture of the big truck crushing the f350......fitting picture.

 

That was merely a photo a friend sent me. I found it quite amusing, merely because it puts it all in perspective - I'm not sure if its that "fitting".

Doesn't matter how big or good a vehicle you create, someone is going to try to create a newer, bigger, better one soon.

That superduty just found its match thats all...

 

i'm was just ribbing you big-f. and your right someones always going to out do you . i did and have always driven fords up til now and it just gets old lstening to all the people talk junk about a dodge. especially when i'm maken the payments. and for me the truck works very well pulling my horses and driving every day. i didnt think i would like it coming out of a ford , but i am very impressed with it..and as always to each his own.