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
