But Ford owns Volvo, so why don't they use Internationals motors. I realize that even the Ford big truck line even offers a Cummins and CAT option. Appearantly some people still prefer one or the other to an International. I think we can all agree they all make good engines, each has their strong points and the Duramax and the PSD are the only two really meant for Light Duty truck applications. The PSD even more so because the Duramax as I hear it started out with a larger displacement.

 

If it was such a problem, a Medium duty engine in a light duty truck I think people would know by now. as for what I see there are no complants. Diesels are not designed to rev high and the higher you rev any engine the shorter the life span of that engine will be. I see guys reving a Cummins to 8k rpm's is that good? yeah but it will not last. I put a 4k gov kit in my truck just to use the rpms when drag raceing or pulling large loads up steep hills. I like to winde it out before I shift so that I don't cover the people behinde me in Black smoke. Does a V8 diesel rev higher that a I6 yes it does. By how much not very. I like haveing my Max TQ around 1400rpms. This means that through to the rear wheels the max tq is about 1600rpms. Now take that and add it to the numbers of a 6.0 and I believe that puts it closer to 2k rpms for a stroker By how much I don't know for I don't have the charts for the stroker so I might be wrong. I don't know about you but I don't like to wate. for anything.

If you all want to come to muncie Indannia june 7th. There will be a sled pull on the 7th and diesel drags on the 8th. Every diesel head in the Norht America is welcome to come.

 

The cummins makes torque peak for longer than the 6.0. Not that it matters because it revs much lower. The cummins has torque peak form 1400 to 2900. The 6.0 has torque peak from 2000 to just short of 3300. The torque is falling off when it makes its peak hp. The higher revs will make for a faster truck.

The cummins is suited well for towing. But it is at a handicap for racing. Not terribly fast. But a good design.

The opener to this thread is deceptive. Is there any vehicle in the 6.0s class?

 

The cummins is good for pulling and not raceing. I agree with in stock form. Now with any engine you start bombing it and it will be better at a lot more things.

 

Why can't manufacturers make double OD units for diesels to keep their revs down. I know the real reason.

 

The Cummins makes 500+ lb/ft of torque from about 1300-2300 RPM's. The 6.0 Power Stroke makes 500+ lb/ft of torque from about 1450-3600 RPM's. That means the the Power Stroke has a torque curve that is much flatter than the Power Stroke. I don't know where you got your numbers, but they seem to be quite inaccurate. At 2900 RPM's on the Cummins it is making only around 300 lb/ft of torque.

 

Have you ever actually looked at the torque curve for these engines? The Cummins does not make peak torque for longer. The 6.0 makes 500+ lb/ft of torque for almost double the amount of time that the Cummins does. At 2900 RPM's, where you suggest that the Cummins is still making peak torque, it is only making about 300 lb/ft.

 

we were talking peak torque right? Cause 500 isnt peak for either engine. The cummins makes peak torque longer. the psd makes 500 longer. Slight difference but worth pointing out. Especially for a hairsplitter like myself.
I read everybodys graph and did the math for myself.

Lets just do the math. 305 hp x 5252 / 2900 = 552 lb ft. You said 300 right. I got 552. Hmm I wonder why the descrepancy. I hope you werent going by a dyno graph that is on the Ford parent site. It is a gross misrepresentation of both products. Creative to say the least. Because if you do the math. The 6.0 is dropping off torque peak when it reaches peak hp.
Thus the cummins makes very close to peak 555lb ft from 1400-2900 rpm. The 6.o makes peak at 2000. And is dropping it somewhere before 3300. 325 x 5252 / 3300= 517. I seen the graph. You are correct. It makes 500 lb ft for longer. I am impressed. But I notice some of the people with sticks complaining that before 1800 its doggier than their old 7.3s. Low power problem possilbly. But if it is making 500 lb ft at 1500 as the graph shows. There wouldnt be anyone complaining. Because 500 at 1500 is superior to the output of the pre '03 7.3. In 03 they moved torque peak down 200 rpm to 1600. 525 lb ft at 1600 is a nice number.
500 from 1500 to 3600 is 2100 rpm. Great torque curve. I would think with it falling at 3300 hundred it would drop below 500 lb ft around 3400. Can you show me the link to the factory dyno. I found one on pickup trucks but it is mislabelled. I would like an official one that is labeled with the correct hp.
Cummins graph shows 500+ from about 1200 to 3000 rpm. Respectable showing. But definitely worth looking into your 300 lb ft figure. 300x2900/5252= A whopping peak hp rating of 165 hp. I say peak because the cummins is rated at 305 peak hp at 2900 rpm. Cummins graph I had to use a straight edge to discern when it was above 500 lb ft. So I must seriously question your double statement. Because using your numbers with a corrected version of the cummins. I got 1800 rpm for the 5.9 and 2100 for the psd. I think its probably closer to 1900 but Thats just me splitting hairs.
The truth will set you free. Ford dyno This dyno definitely shows somewhere between 3300 and 3500 the torque falls below 500. An optimist would say 3500 a pesimist would say 3300. So its 1800 rpm for one and 2000 for the other. Pick one. I think you will find my est. of 1900 to be very close in the end.

The 100 rpm broader torque curve would explain why the psd kicked everyones butt on the pickuptruck.com test. But my original statement was correct. The cummins makes Peak torque for longer. the psd makes peak torque for 12 or 1300 rpm and the cummins make peak torque for 1500 rpm. Where did YOU get your numbers?

 

How flat the torque curve is only matters if you are constantly accelerating. For instance, racing applications.

When you are someone who uses these trucks for their intended purpose, which is NOT racing, all you care about is WILL it pull the load. And the peak torque is what matters here.

Ford = 560 lb./ft.
Dodge = 555 lb./ft.

OOOhhhhh big deal....the PSD makes 5 more lb./ft. of pure torque. And it needs TWO more pistons to do it. I'm still not impressed. If Cummins wanted to, they could turn the 5.9 up some more and completely wipe the floor with the PSD. The 5.9 is capable of so much beyond what they are tuned to from the factory anyway.

Furthermore, no one is going to keep adding weight to their trucks until they reach the absolute breaking point, so the 100% capability of a Dodge or Ford will never be reached anyway. So it doens't matter which you buy...they both will do the job.

What matters then, is which will do the job for the greatest number of miles? And we haven't seen yet if the 6.0 can last nearly as long as the Cummins.

 

WX, dont forget that on hilly terrain the engine will need a broad torque range to keep speed up the hills.

 

I must put my two cents in this consversation. If you want a truely fair comparision of diseals you must take not their displacement nore number of cyclinders into account but their design type. Any true diseal person knows that an inline diseals motor will do better, last longer, and will be cheaper to maintain and fix major problems. Here is one example: My dad is a farmer and because of this he must have tractors that are big enough to pull 40' air drillls so you need 300hp tractors minimum(this is a medium sized tractor with a motor around 800+ cu in motor:not sure on that size but i think that pretty close) Anyway my dad used to have a Versatile 900 tractor that was around 320-350 hp. It was a good tractor but because of the V-8 it just got to be really expensive, and when it was compared to my uncles 875 I-6 tractor it would get its but handed to it in the fields. So my dad traded it for the same model as my uncle and now(all these are cummins turbo power) we have the ability to pull air drills without worry of blowing the motor and having a $15,000 (easily) motor rebuild. All in all an inline diseal is a better motor and has better potential, it just depends which is hooked up to the better powertrain to deliver what the motor is capable of, and in this case i believe that powerstroke has the better powertrain so in turn you see what the motor is truely capable of.

 

I suppose choice of transmission comes into play here as well. I am thinking of manual transmissions (which is traditionally what most people want in a large truck). In this case, you can use whatever gear is necessary to stay in the powerband of the engine...regardless of how broad or narrow it may be. If you consider the computer-controlled automatic transmissions then I guess it's a different ballgame because the truck decides when it needs to shift for you, so a broad powerband would be nice. Automatics are also dangerous though, because as the original post explained I think...sometimes computers are no match for pure human intervention and if it decides to downshift on a steep grade with a 15,000 lb. trailer hooked on you might have serious trouble!

 

'tis true, but where I live if I want a manual tranny I have to SPECIAL ORDER IT. Sucks..........

 

The Powerstroke is a "Light Duty" engine and the Cummins 5.9 is a "medium duty" engine. The Powerstroke isn't even in the same class as the Cummins. Enough said.

 

I said that before but they don't agree I guess the reason is because the Cmmins does not have as long a tq curve compaired to a Powerstroke. I have never looked at a dyno sheet so I don't know But there are enough nice guys on here I think I can trust them.