So I have had a few hours to collect my thoughts on the visit to the Columbus Engine Plant today, and as I type this I am recalling even more details that I would like to report. I can’t say enough good about the Cummins team; they were fully aware that I am just an end user, an owner, and really went out of their way to host a fantastic tour for me and my friends during our visit. We spent over an hour out on the assembly line floor discussing all the steps to machining, assembly, and test for the Cummins 5.0L V8, and then we went into a conference room where we met with a team of 5 Cummins employees and discussed things like reliability, user experience, fuel consumption, parts availability, and other topics that just came up in conversation, for over another hour or so. We had a nice lunch in downtown Columbus, then wandered over to Cummins corporate HQ where we took a look at the museum they have there with some vintage engines, some examples of current production engines, and some vintage Cummins-powered cars. They could not have been more gracious, and if I had any reservations about Cummins as an organization before (which I did not), I certainly would not have any now!
Some things we discussed during the tour in particular, some were nebulous, but they answered all my questions, and I am sorry that the owners here on the forum didn't have more questions for me to hammer them with. Cummins is really starving for owner feedback on this motor and chassis combination, and only having a few miles of experience to draw from, all I could really do for them was give them my perceptions, comparing it to my last Cummins ISB 5.9L inline 6. One disappointment was that although the 5.0L is substantially similar to the ISV used in medium duty commercial vehicles, they intend to only supply parts through Nissan who, along with every other OEM automaker, tends to be sky high on pricing. That’s not to say that Cummins wouldn't sell over the counter to anyone who walked in with a part number, but I think that they are going to really fall back on Nissan when we need parts for this engine, as opposed to the experience I had with Cummins and the 5.9, where you could walk into just about any Cummins service center and get parts for that engine.
We were not allowed to take any photos on the tour, but if you go on youtube, you can see press video from the Cummins/Nissan launch where you can see essentially everything we saw. All the parts come from vendors; the blocks come from Brazil (I think that’s what they said), the heads are outsourced, and the crankshaft forgings are all specced and brought in from outside. They don't use robotics as extensively as I expected; most of the machining and block positioning is robotic, but the major assembly is mostly human interaction with the exception of the camshaft installation. Each part is recorded on a birth certificate, and you can see the part numbers and some serial numbers if you register your engine serial number on Cummins QuickServe Online; there is a major assembly build sheet with all that data so if there is ever an issue with recalls or faulty batch parts, Cummins can quickly locate those engines and parts in the field. The lower blocks of the 5.0L and the ISV travel a common line during assembly until they get to the installation of heads and then they split with automotive on one line and commercial on a second line. This is because the heads are slightly different, cam timing and intakes and turbos and such, due to emissions differences and fuel mapping variations. The commercial versions have several different options and the automotive versions are all standardized (at least for now, that presumably would change if another OEM would pick up the engine for a different truck). Every engine undergoes cold testing and every engine undergoes hot testing as well; 100% of each assembled unit undergoes both cold leak and torque and fueled operational firing. On the assembly line, they said that they have an 80% assembled unit no failure recorded statistic; that is to say, that during assembly, 80% of the units show no sign of abnormalities during measurement or QC inspections and tests, and the 20% that do, get reassembled, and retested. They said that the top five causes for reinspection and testing were phantom computer recorded failures, and I don't know if that is good or bad, but those were their numbers. The number of final engines that meet spec at hot test is above 99%. Apparently Cummins was astonished at the QC requirements for the engine that NNA specified, so evidently Cummins had to really step up the quality assurance game for this engine, at least according to the Cummins team. The ECM is supplied by Cummins and mated to the specific performance map of the engine, which was recorded during hot testing. They have lots of room to ramp up production, and I fully expect that they will soon. They would not talk about other OEM’s using this engine other than BlueBird school buses, Tiffin Motor Coaches, and Freightliner (I couldn’t find any specific equipment information for Freightliner equipped with an ISV online), but they did specifically say that there is no exclusivity arrangement in place with Nissan, NA.
During cold testing, they measure lots of pressure and torque parameters, but one thing that surprised me was that Cummins records instantaneous torque force for 360 degrees of crankshaft travel, as opposed to just recording starting torque and averaging running torque for the engine and gear train, so they have an entire normal torque force map for each degree of crankshaft travel. It is an interference engine, and so I am very appreciative of chain drive rather than belt drive for the cams and valves. The engine block is not sleeved, and when discussing reliability numbers to date, Tim Britt stated that their test engines in Titans had accumulated over 200,000 miles of testing with normal wear and tear expected for that endurance. They did not say if each of the test mules accumulated more than 200,000 miles or if it was combined testing, but I suspect that was the case with each individual engine. I asked if that was comparable to the same wear that could be expected from an ISB 5.9 or 6.7 and they said that wear was comparable. I don't know if its reasonable for us owners to expect million mile engines from this platform with care, but they seem to indicate that it is possible, yes; likely, who knows? The Cummins team stated that the highest mileage Titan XD on the road with a consumer that they were aware of now has about 33,000 miles on it and counting.
Cummins is big on user experience. I was the only one in my group who owns a Titan XD, and they really grilled me on the whats and whys of my purchase. A big why for me was built in America with American engine. I had a Ram 2500 built in St. Louis, but now I think all of them are built in Saltillo. Some people don't care about that, I happen to. To each his own. One thing I told them that bugs me about the Titan and the Cummins implementation is that Nissan elects to display the auxiliary gage data as dummy graphs with L/H and no real numbers to equate what is normal and what is abnormal. Call me anal, but I like to equate a number with parameters; if the temps are normal, I want to know that a range from 170-235 is normal temperature for coolant, not H or L. They agreed that this is a Nissan deal, it could be displayed any way the OEM wanted. Another thing that I have noticed is the DEF gage has no real indication of quantity, and that bugs me, too. Doesn't seem to indicate deplete in a linear fashion. The final thing that bugs me is something others have posted here, that there is no clear indication of Regen and when it's happening. I asked Cummins how to see it and they indicated that it should be seen by instantaneous fuel usage and exhaust temp increase, but I said that from my limited experience, I see wild differences in that instantaneous fuel usage with no real change in exhaust temps. The only real indication that I see is the DEF gage quantity dropping during normal usage but that tells me nothing. I’d like to see some annunciation that Regen is actually occurring and when its done since Cummins said that Regen was computed and initiated by a couple of different exhaust and pressure sensors in the exhaust stream; they did not know exactly what sensors Nissan selected to be displayed (such as pre or post turbo or pre or post cat) when the Titan XD displays exhaust temps. Maybe the Nissan service manual tells us? They also asked me how I felt about being an early adopter of the XD and whether or not that concerned me. I replied that I had tons more confidence in the powerplant after the visit than I had before, since I got to see just how robust this engine really is disassembled. I also said that my wife and I have had great results from two Muranos, the first being a 2003 launch year model and we had trouble free service for 260,000 miles from that car, and the second is a 2013 with 44,000 miles. That being said, the Titan XD chassis/Cummins combination was not a stretch in confidence for me at all.
I lamented that Nissan did not choose to install block heaters in the lower US trucks, and Cummins said that they think I will be pleased with the starting performance with the ceramic glow plugs and wont miss the heating element. I have a hard time wrapping my head around how a preheating measure can be somewhat irrelevant, even if the ambient temps don't drop to below 0 degrees F. From experience, I know that warm lubricant in any winter weather is better than cold lubricant, but since I don't have any cold weather experience with the 5.0L to draw from, I will have to take Cummins’ word on this. (I’d still like the option of a block heater, whether it’s necessary or not. Nissan: hope you’re reading this)
I would like to know and thought about this on the way home if the rotary turbo diverter valve could be implemented through software to act as an exhaust brake. I seem to recall reading that it could be used that way, but I can’t find anyone at Nissan who knows if it was tested that way in the Titan. I do not believe that it is implemented that way in the released version of the Titan, nor do I know what effect that would have on the transmission or drivability, but it seems to make sense that it would be a good implementation to make it work that way. Maybe if enough owners gave NNA some feedback on that feature they could enable it, but doubtful. I will have to email Cummins and ask them.
So that is my trip in a nutshell. Cummins wants more user feedback on this motor since this is the first widespread automotive implementation for it. We had some conversation regarding some other things Cummins has in mind for diesel Titan owners, such as a dedicated owners reunion like they have every couple of years with Ram operators. It would be a good thing for us early adopters to let Cummins know that we want that, and the information on reliability, maintenance, and feedback we can give back to Cummins would be mutually beneficial. I think it will be a solid engine for us. A very interesting visit to a very informative company, and I felt that they were as forthcoming with any information that they were at liberty to share, and I believe that it was the right decision for me to go with the Cummins, even though the 5.0 is a new engine (to me), in a new chassis platform from Nissan.
MB
