I AM IMPRESSED

[jcmseven]

Oh, Builder!! Here we go again....I know we speak of the Cummins, but someone needs to keep the 6.4L bash in check before it gets away again. It is true the torque curve of the Ford is later, but if one believes this graph, its curve meets the Duramax torque curve, for example, at around 1900-2000 rpm, and then passes it. This is not by mistake, but happens to be where the Ford with 3.73 gears happens to settle when running on the highway at 65-70 MPH in OD, about towing speed for most today on the major interstates. If one shifts into "tow-haul" it will rev at about 2500, which is in the meat of its curve. It also correlates well with the shift points in the transmission. My truck idles at 900 prm, which would generate "off-idle" torque similar to the Dodge. This graph also seems to show the Blue Oval's graph showing more peak torque than either of the others. It also shows something (though the graduations could be slimmed a bit for a better comparison that has been shown before: the Duramax rating might be a bit generous, and the Cummins/PSD a bit pessimistic). I recall an article in "Truck Trends" back when the 7.3L Ford and the 5.9L Cummins were both out, and the Duramax was rated at less HP than now. They performed chassis dyno testing on all three and the Ford and Dodge were underrated and the Duramax was "generously" rated, based on actual numbers. As for the Cummins, it is a pulling motor. I agree the torque curve of the Cummins is perfect for towing. It will not win any races v. the other two, but with the low onset of torque and the very flat "curve" it would feel very strong and would be a very efficient puller. Only at the limit of performance and RPM would it lose ground to the other two. Yes, this is but one graph of many I have seen, but the theme has been the same with each. Who knows how accurate this curve really is, but it shares similarity with others I have seen. Again, though, I think one must keep in mind truly how similar the performance curves of these three powerplants really are. As for the economy, looking at towing numbers on the post-DFP trucks they are VERY close. The Dodge/Cummins is usually best, but not by very much.

John M

 

[jcmseven]

JB4310,

I cannot attest to the man's truck you heard but my 6.4L is a very good starting truck, even at or below zero degrees F. The only time that the truck will sound rough after starting is if it is preparing to go through a regenerative cycle. I have had mine sound this way twice in my ownership of it. Both times, it smoothed out once warm and once the "regen" cycle had occurred. I do not know how many miles the man's truck had on it, but he could also have a DPF with some residue in it which could cause this. In either event, I doubt it is as a result of an engine issue. There have been very few injector issues with these motors, so the chance of that would be very slim.

John M

 

[JB4310]

Yeah, you never know with these new trucks, my new 6.7 is almost to quiet but one time I started it and it sounded just like the old 5.9 for a couple of minutes.

Dodge was having alot of problems with programing in the blue tech equipped pick ups in 08, don't know how that's been resolved. I have the first year 07 cab/chassis with 6.7 which doesn't have blue tech engineering but does have a huge DPF and an EGR system, had a few issues with regen cycles coming on to often IMO, but the truck seems to have ironed itself out, never had any reboots or software updates.

The software in these things is way to far ahead of the hardware and the techs really don't have a clue when there's a glitch.
It is the age of the machine, the PCMs are intuitive now, and learn as they go. my PCM has a parameter of 10,000 functions!

JB.

 

[RobertN]

As for the Cummins, it is a pulling motor. I agree the torque curve of the Cummins is perfect for towing. It will not win any races v. the other two, but with the low onset of torque and the very flat "curve" it would feel very strong and would be a very efficient puller. Only at the limit of performance and RPM would it lose ground to the other two.

I agree with most of the rest that you said. And, IMHO, these trucks are so close, it comes to personal taste and preference. If they are stock, or even mildly tuned, they are very close.

From stuff I have read though, for the most part, Cummins powered trucks rule the drags and pulls. Powerstrokes and Duramax's are in the mix too, but when you go for all out performance, the Cummins is like original Hemi; it was the one to beat.

A person certianly could not go wrong with any of the diesel pickups from the Big-3. I personally like my Dodge, and like the Cummins. When time comes for another truck though, I will definitely look at and drive them all. Hard part is I got my truck as a 300,000 mile endeavor. It is 8 years old and I only have 116,000 miles on it. Looks like another 15 years or so before a new truck My previous Ford F250 gasser had 225,000 on it and was in great shape, so I can see 300k... By then these pickups will be making more power than the 8.9l ISB in the fire engine at my station.... I can just see it, a 2224 Ram 2500, with 700hp/1200ftlb

 

[Builder]

Oh, Builder!! Here we go again....I know we speak of the Cummins, but someone needs to keep the 6.4L bash in check before it gets away again. It is true the torque curve of the Ford is later, but if one believes this graph, its curve meets the Duramax torque curve, for example, at around 1900-2000 rpm, and then passes it. John M

But the Dmax torque curve starts waaaaaayyyyy earlier. That's grunt torque my friend. The little bit more TQ the 6.4L makes (looks like a maybe 10 ft lbs) during about the 2000-3000 mark is of very little significance and probably couldn't be noticed by the average truck owner. Then look what happens to the 6.4L at 3000RPM. It drops like a boat anchor. The DMAX keeps it's flat torque curve going beyond 3000RPM past the 6.4L.

Now look at 1500-2000 RPM. The dmax is blowing the 6.4L's doors off. That's the torque any good diesel engine designer always puts in a good diesel engine-gets the load off the line and moving...trucker's torque.

I'll take the noticeable superiority of the dmax over the 6.4L in the 1500-2000RPM range over 10 less ftlbs after the load is moving. I'll also take the flatter torque table.

The thing that really gets me shaking my head is that ford basically introduced this engine half way through 2007 with twin turbos and a lot of hooplah. Is that the best they could do against essentially a 8 year old GM design and an ancient Cummins design? You'd think Ford would have designed something less complex maybe in the 400HP range with such a new "groundbreaking" design.

Guess that's why Ford is dumping it after 2&1/2 years. They are so disappointed with IH, that they're severing a 25 year relationship with them to seek a new diesel supplier. I can't blame Ford for doing this. Despite a big sales advantage, I can't think of one year since maybe 2002 that I would pick any of the 3 powerstrokes over the same year Cummins or Dmax.

I hope they pick a really good new engine. Maybe next time around, I'll buy a Ford.

 

[Diamondpilot]

Again this comes down to total package in my eyes. We all want something different, that is why we spend our hard earned money on what we want. I prefer the Ford toughness over a few more HP or flat torque curve. Never owned a Cummins but did own a 2005 D-max and it was no more powerful than any other diesel I have owned and a lot less truck.

Chris

 

[Builder]

I really am curious to see how many guys sell their 6L's & 6.4's for the new "scorpio" diesel. You'd think the value of the discontinued 6L & 6.4L's diesels will drop noticeably since neither were exactly legendary, like say a 12V Cummins.

The thing I like about the 6.7L Cummins is, like the Allison transmission, is that Ford uses the it in their medium duty F-650/750 instead of the 6.4L (or the previous 6L) .

That really underscores how Ford feels about their own 6.4L diesel engine and their own transmissions compared to Allison transmissions and Cummins diesels. The ultimate compliment to your competiton is to use their engine or trans in your own heavier duty trucks.

Unless ford hits one out of the park with the scorpio diesel and installs a real transmission in their 4th truck drivetrain design variation in 8 years, I'll be back in a GM or maybe switch to Dodge for my next truck.

I think by then, Dodge will have the 6.7L DPF system de-bugged and the 3500 chassis is already available with an Aisin trans and an exhaust brake.

 

[JoelD]

From my experience, 4:10 gears pull super hard.

Joel

 

[Builder]

From my experience, 4:10 gears pull super hard.

Joel

It all depends on the transmission and the way it's geared and the torque band of the engine. I learned this while driving bigger trucks.

I don't desire high-rpm torque because I don't run high rpms. I run my truck at low rpms to save fuel. Most of my trips are in stop/go traffic, so I like more gears and more low end grunt.

I probably would have been even better off if I had gotten a 1-ton DRW with 4.10's, but my 1-ton SRW with 3.73's is doing real well.

Next truck is crewcab dually 1-ton.

 

[jcmseven]

Builder,

It's all about the lines. You mention the notable superiority of the Duramax from 1500-2000 RPM. Actually, it appears to be 1500-1800 or so (a 300 rpm window) at which point the "superiority" of the 6.4L holds from 1800-3200 or so, right in towing range. The patriarchal way of looking at this holds little appeal. A tutorial is unneeded. Perhaps that is a very important 300 rpm window, but ALL the engines make plenty of torque for getting loads moving. Really where torque is most helpful is keeping them moving over varied terrain. The Ford produces most torque right where it is most needed. It is not very often that my RPM exceeds 3200 and then it is not very long. When the data lines intersect, we do not know much about what happens after that. You focus strongly on the initial torque, yet you mention that the 6.4L drops like a "boat anchor" after 3000 rpm. So which is important?? Another stab at the "Blue Oval??" We cannot surmise why this is and to assume it is a legitimate drop is erroneous. Was the test terminated? We don't know with certainty, but we do know the yellow line also ends at about the same RPM for its test. Assuming it is a real data line--and a metanalysis of independent testing-- how much of the time do any of us spend towing at greater than 3,200 RPM with our trucks?? I can tell you my 6.4L pulls plenty strong even above 3,000 RPM but I do not spend much time there. I know you have mentioned you want the "best truck" and are not brand loyal, but it seems this might not be totally the case. I am brand loyal, and admit so. I have had good luck with my product and found it to be competitive with other offerings currently out. With regard to brand loyalty, one espousing not to be, then exhaulting attributes of the product one owns while downplaying certain aspects of other offerings (yes, the blue lines are ABOVE the yellow lines on our graph between the RPM's noted--isn't the DM supposed to have more torque??) is brand loyalty. We can all find bits and pieces where our machine is rated better, runs better, etc. I do this, you do this, we all do this. It is OK to be brand loyal. You also mention (again) that Ford's design was not up to snuff. First, the "twin turbo" design is actually a dual sequential turbo, not a TRUE twin. It is also not a bad engine, an implication you have repeatedly made. It is durable, very heavily made and obviously makes plenty of power, as per the blue line. Where is that yellow line again? Ford does use Cummins and Allison products any many of their medium duty trucks, of various levels. The Allisons used are at times unique to the application, fit well with many frame and chassis applications, and are good transmissions, in general. They are not without fault, but overall are solid. Many medium duty applications are well-suited to an in line 6 configuration, so I am not sure any major conclusions can be made there about the 6.4L not being a suitable choice. The power numbers are there and the service interval is similar between it and other diesels in this class. I also do not feel the 6.4L engine was the cause of any termination in relationship between Ford and IH, but mainly issues from the preceeding 6.0L early production engines. I feel perhaps conclusions are being drawn here that might be a bit reaching. I too wish Ford had carried this run of engine longer, but I suppose we could look at it as more a desire to continue diesel development for more power, durability and economy. If Ford's "scorpion" diesel has 430 hp; 750 pound feet of torque and gets 15 mpg pulling with a 400,000 service interval then the change might have not been so bad and the other companies will be scrambling. As for your next truck purchase, when you are ready to buy, I think a Dodge or GM would be a fine choice.

John M