Hello, I drive a big truck and I like efficiency

[Backtobasics]

One thing I have not read in this thread was propane injection. While I am not thoroughly versed, what I have read is that it is great at cleaning up an overfuel truck, but that it also can be programmed, to augment the diesel used, extending range, and increasing MPG.

quick searched article here, on Dodge:
Dodge Ram Cummins Diesel Propane Injection Performance | Mopar Muscle Magazine Article at Automotive.com

[slowmover]

Propane injection works well when the cost of propane is low, relatively. The btu content per "gallon" (rough equivalent) is lower than diesel; maybe 2/3'rds. In some states (Utah) this is $$-efficient. In most others one simply has a dual-fuel vehicle to extend the range of available diesel (were there a shortage). The cost is easier to absorb than a CNG (compressed natural gas) conversion/addition, but CNG stations are fairly rare (search for nationwide locator); one can also spend $$$ for a home compressor station. Propane is widely available nationwide (and be aware that one must pay road tax for fuel in either case; an expensive citation if not properly registered).

Both add complexity and weight to the truck, not to mention reduced space.

Both should also be viewed on a graph comparing also WVO and WMO.

The great thing about a diesel is that all can be considered.

.

[slowmover]

Originally Posted by Diesel_Dave

slowmover,

I think we actually agree on more than we disagree on. Mainly, people shouldn't play around with changing things that you don't understand. I guess I just come at things from a slightly different perspective because I've worked in diesel R&D for several years.

I also believe we do. Very few of us have, however, the knowledge, skill and tools to gauge the condition of an electronically-controlled diesel engine. A gasser is simple in comparison (and everything is far cheaper) when it comes to assessment.

On the other hand I'd take chances with a $6k gasser longblock (engine cost) that I never would with a $18k Cummins. Had I a cousin at the local CUMMINS dealership I might be more willing. If I knew of fleet comparisons I'd be more willing to try aftermarket parts. The usual enthusiast crowd is short-term ownership and abusive, by definition. (And I won't leave out those who use trucks for their livelihood as I've seen too many with no feeling for, or records of, proper maintenance procedure. For just a start).

What we do has to work. If we have no way of gauging long-term effects then the gizmo is suspect from the beginning.

.

[Dad]

JustLuckey,

Congrats on the birth of your son!

I also have a 2005 Dodge Ram 2500 4X4 CTD but mine is a LWB and has the G56 6-speed manual transmission. I LOVE my truck. My best (hand calc) FE in the truck is 22.5mpg, but I'm usually in the 21-22mpg range most of the time. Everything is stock on the engine, stock wheels and tires, and stock ride height. I have a Pace-Edwards JackRabbt tonneau cover that helps a bit with mpg's. Also, I tried the tailgate removal trick, and my mpg's actually went down slightly. My best mpgs are with the tailgate up and tonneau cover closed.

IMO, these trucks can probably be pushed to higher mpg's, but what I ran into is that these Cummins diesels don't like to loaf along under light load for too long or they complain. They're meant to be worked, and if you don't work them, they get sluggish, run rough, and suffer from wet stacking (washdown) leading to increased fuel dilution in the oil. Just not worth it, IMO. I ended up having to run the truck hard periodically or hook it to a load just to prevent too much cylinder washdown and get it running right. And that negates the FE efforts. Also the Cummins is just not conducive to many hypermiling techniques such as FAS-ing. I love my truck a lot and refuse to part with it though. I have 170,000 miles on it and hope to run it at least another 170,000 miles. But, I finally decided it was more efficient for me to park my truck and commute to work in my minivan instead. The fuel cost savings alone on my 140-mile daily commute, along with carpooling, actually is enough to fully cover my minivan's loan payment and then some.

I'll be interested to see your progress in eeking more mpg's out of your CTD though. One thing to consider looking into is getting a programmer that will eliminate that third injection event, which only serves to clean up the CTD's emissions. My understanding is that you can pick up another 1-2mpg just by making this mod. Maybe one of your existing programmers already has this capability. Good luck!

[slowmover]

what I ran into is that these Cummins diesels don't like to loaf along under light load for too long or they complain. They're meant to be worked, and if you don't work them, they get sluggish, run rough, and suffer from wet stacking (washdown) leading to increased fuel dilution in the oil.

I read this in other places online, but find no verfication. Oil analysis or Dodge TSB re-flash, or?

If one runs the truck lightly then the ECM adjusts to that. If one is loaded heavily, then the ECM adjusts to that. Remaining in any condition just long enough and the computer will use accumulated data on the most recent several hundred or several thousand miles. I can park the trailer and notice that the truck is "peppy" compared to use when solo until it re-adjusts itself. That is not performance degradation. If it were, we'd see CTD life as short as too many Fords or GM diesels (ha!); really, a motor running that way has a shortened life.

Our two trucks are not identical stock from factory, granted. Yet it's fair to state that what you've described as a One Note Johnny engine (only works well under a prescribed condition) is not borne out by much other experience, and, without verfication, is suspect. I might remember to go WOT once a month or so, and I might remember to use some fuel treatment once a year (usually now, during hurricane season). Were the premise stated correct then I would see a degradation in FE due to my use. I don't. This time of year I break my self-imposed "no idling" rule as it is too danged hot. This single factor reduces my in-town economy as shown by a decrease in average mph. Light loads and light throttle are just fine with an HPCR CTD.

Hope to read more of your experience with that truck (and all other CTD's). The bed cover and tailgate "up" is backed by much experience, and by expertise (from the OEM manufacturers, among others). Reduction of rolling resistance is the place to spend money, IMO, and the experimentation (mainly on this site) of aero aids to pressure drag reduction will pay some dividend if highway miles are high enough to justify them. The cheap DIY approach, here, is great (versus the cost of aftermarket toys so many are enamored of for pickemups) for investigation of pressure drag reduction.

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[Diesel_Dave]

Dad,

I really wouldn't be concerned too much about fuel dillution at light loads unless you have some info from an oil analysis showing it. Since the advent of the common rail, the injection timing is adjusted for different speeds & loads. Older, mechanical fuel systems had to keep the same timing everywhere. Especially if you're running stock, I would be suprised if you had any issues. That being said, if you're concerned about it just have an oil analysis done.


slowmover,

ECM's don't "adapt" over time. In some cases, it can go into or out of different control modes/look-up tables (steady-state, transient, high altitude, etc.), but the ECM doesn't "learn" anything. Eventually, that might happen (I've talked about it a little with other folks in the industry) but it's not in production today. The technology is actually out there to be able to do such things. One of the biggest problems, however, is dealing with the EPA--how can you prove to them that it will always meet emissions if it's always adapting itself? It's not impossible, but it's really difficult.

I'd say the difference that you notice after pulling your trailer is psychological. Just like like when you ride in a car again after driving your truck so much and it feels so wierd that you're sitting so low to the ground.

[skyking]

Thanks again Dave. I dream of an affordable adjustable timing gear for my old 12V. As it sits, I must go with what works best.
12V + mappable timing = pure win, IMO.

[Dad]

Thanks for the added info guys. Yes, common rail injection has provided dramatic improvements in diesel efficiency. Only downside is that these common rail systems are a little more sensitive/finnicky, but careful attention to fuel quality and filtration takes care of most of that. Although I still have concerns about this ULSD and its possible negative effects (shortening their life) on these injectors.

Anyway, my concern is based on two things: 1) Oil analysis from Blackstone Labs. I had a test done on an oil interval that was all unloaded commuting and compared against oil analysis from running loaded and dilution was up substantially on the unloaded interval (something like 3% running unloaded vs less than 1% loaded). It was a few years ago so I'll need to see if I can dig up the reports to give you exact numbers. 2) Personal observation. After running light unloaded for some time, the truck's performance becomes quite sluggish. Then when I hook up some weight behind it and run it hard for a while, then unhook, it has all its power and economy back again. It seems to respond well to the old "Italian tuneup," in a sense, to clear it out and clear the unburnt fuel. Also, after loafing along for a while and then getting on it, it blows quite a bit of smoke for the first couple WOT runs until that unburnt fuel is burned out of there. You guys with the newer 6.7's may not notice this much, but the old 5.9's do it. Anyway, while the common rail injection system is dramatically improved vs the older mechanical injection, I do still tend to believe they don't quite run optimally at very light loads. It's probably not quite achieving complete combustion of all the fuel at very light load, but that's just my guess from what I've personally observed. Anyway, maybe there's more to the story that I don't know, but based on what I've learned and research so far, this is what appears to me to be going on with these CTD's. Despite this, I still love my truck and they'll have to peel my cold dead hands from the steering wheel to get me to part with it.

[slowmover]

Despite this, I still love my truck and they'll have to peel my cold dead hands from the steering wheel to get me to part with it.

Yup. Best vehicle I've ever owned on a cost-per-mile against potential work-per-mile basis. A Camry for mpg, but can pull a house down the road. DD, I'll grant you the word on the ECM, for now. As to dilution I'd like to see numbers as I believe only extensive idling (as a percentage of total hours) will show a rise on an HPCR (given a truck with no magic gizmos attached).

.

[wilcorp70]

Seriously, more people need to think about aeromodding their big trucks. My uncle drove an 18 wheeler, and I swore I could have cut his fuel bill in half with a lot of fiberglass and bondo.