Hello, I drive a big truck and I like efficiency

[Diesel_Dave]

Congrats on the birth!

Regarding the tunes, just start trying different things and keep a record of your mpg on a regular trip (to work and back for example). Just see what works best.

My 6.7 engine has the advantage of a VG turbo rather than the wastegate turbo on the 5.9 so that probably helps the smoke. Also, the 6.7 has an intake throttle that needs disabled/removed to avoid smoke issues with a lot of tuners. I don't think that the 5.9 has a throttle, but you might want to check.

[Diesel_Dave]

Also, I don't think that you really have to worry much about a hot tune doing damage to your tranny, etc. --- as long as your just doing daily driving without much load. The only time I'd be concerned about that would be if you're really pushing the engine (towing a lot, etc.)

[skyking]

I sympathize regarding the wife. I purchased an auto so she would feel comfortable driving it some, but I keep adding doodads that are beyond "put it in drive and go". Totally to her credit she has driven the truck/5th wheel combo with relative comfort.
I have a powerful exhaust brake that also has the annoying function of locked shifts from 3rd to 4th. I remember to either let off the throttle or have it disarmed, but I can't expect her to do all that.

[backyard engineer]

congrats on your little boy. I'm glad to hear of your willingness and interest to conserve. any and all efforts are appreciated if only from afar.

[slowmover]

Nice numbers thus far!

I'd be careful about having replaced the mechanical fan if heavily loaded or contemplating towing. DODGE would have gone to them (as would makers of big trucks) for FE reasons long ago if they were capable of moving as much air as a clutched mechanical fan. They aren't. I leave mine as is for the practicality of the wide range of work a truck can perform. A truck is either income-offsetting or income-producing. If neither, then another vehicle is warranted. Frankly, the fan change is a crippling move.

In that same vein there are problems that bear investigation, especially on the 4WD models, namely, steering and front suspension component that wear somewhat fast and are re-engineered on later models. Plenty of threads on upgrading on Dodge-specific forums. (Same for HVAC performance, etc). All of these are "economy" in that we are increasing the per-mile cost of ownership, however reluctantly.

The first step for truck FE, IMO, is very careful record-keeping. Understanding the costs as expressed in a cents-per-mile format. An understanding of truck use (percentage highway vs percentage city) is only seen through records, not "what I think it is". Average mph and average mpg go hand-in-hand together. One begins by forecasting ownership life and annual miles.

For truck FE: Truck spec is first, terrain/climate is second, and driver skill is third. The first two cannot be changed, only accommodated. The third is ripe for exploitation if one can get some distance from the usual emotions around driving, primarily the convenience of 24/7/365 usage. Restrictions of use -- such as no single trips (combined trips only) -- are a good first step to see what works. And roll into that a "No Left Turn" policy such as UPS uses.

The difference between the best and worst professional drivers is 30%. Call it a one-third difference in the amount of fuel used to accomplish the same task. Same truck, same work.

Thus I have little patience or belief in aftermarket gizmos that only add to cost -- some with the propensity to shorten vehicle component life -- and the use of which tends to overshadow driver skill improvement (and the gizmo is given credit). A stock truck is the best baseline, and for a factory-delivered Dodge maybe a camshaft change plus timing advance is worth 1-2 mpg annually assuming LRR Michelin tires. (Modified trucks are so far out of spec as to be worthless for comparisons unless one can find an exact match as to spec, terrain and use).

The aftermarket gizmos also increase depreciation and add to the "initial purchase price + finance cost" line of a spreadsheet. One can go through the items mentioned each by each, but let's admit that wishful thinking is part of the "equation" (unless, again, we can corroborate the changes with a similar spec truck in a similar climate/terrain and cross-our-fingers hope that driver skill is similar and that records are honest).

For what it's worth I'd can the go-fast stuff and look to other changes as mentioned; tire spec being the single-most critical change after safety is covered. Bed cover, grille block, air dam, belly pan, etc, can all be experimented with cheaply (and some great stuff to read around here per some other owners).

Start with wheel-by-wheel weights from a certified scale when "empty" (full fuel plus driver plus normal stuff in truck), and scale again (axle-by-axle) when loaded. A stack of scale tickets is handy for comparison purposes. I did this initially to set trailer hitch rigging, but found that it was also useful in predicting FE for a given trip. IMO, if one cannot predict the mpg of a given trip, then more homework is needed. Same thinking for tire & brake life: less than 70k on either (for an on-road vehicle) then the driver is in need of remedial training.

Proper tires, proper alignment, and detailed attention to mechanical drag (system by system) is the first "real" step after complete records establishment. Maybe manual hubs will help, for example. I've seen reports of yes & no. Aero improvements are only relevant to a truck that spends enough time above 50 mph to actually recoup costs. An in-town commuter, a local contractor, is unlikely to see enough change to matter.

FE will be the percentage change of average (overall) mpg change from baseline. If my annual mpg changes from 22.48 to 23.61 mpg over 15k miles, then I am on the right track. 5% has meaning, here, where "1-2 mpg" does not. The particular "blend" of steady state highway speed versus in-town stop-n-go is nullified when looking at changes in this manner.


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[Diesel_Dave]

slowmover, just a few comments on what you said.

1) On the fan, you're probably correct. My thinking is a CLUTCHED mechanical fan is probably superior to an electrical fan from an efficiency perspective because there aren't the conversion losses ( I can see where an electric fan would have an advantage over a non-clutched mechanical fan). Also, unless you're doing a lot of driving where you're really working the engine at low vehicle speed, I don't think you're clutched fan is going to run that much anyway.

2) Your note on careful record keeping is right on. If you're not doing that you're just fooling around.

3) I totally agree with your point that you have to think about all mods from a TOTAL cost perspective, rather than only a FE perspective. If you spend $1,000 on something that improves your FE by 0.1% on a pickup you're crazy.

4) Regarding the "aftermarket gizmos", I have to disagree somewhat with what you said. You really have to look at things on a "gizmo by gizmo" basis. You are correct that some mods are going to result in premature failure, so don't do those. However, some mods will actually increase your mechanical life IF done correctly (removing EGR for example). The key is to be patient and really understand what you're doing BEFORE you do it. Know what to do. Know how to do it. Know why to do it. You should research the whazoo out of a mod before you go out and do it.

5) Maybe I misunderstood you, but you seem to have the idea that, "If it led to better FE and/or better engine life, then the manufacturer would have done it so don't mess with anything." This I have to disagree with. The one thing that you're forgetting about is emissions regs. Engine manufactures have been forced to add components and calibrations that significantly hurt initial cost, engine wear, and fuel economy. Case in point are the DPF's (diesel particulate filter). They add a bunch of initial cost, a bunch of maitenence cost, burn a bunch of fuel (both in regens and added backpressure), and they prevent the driver from driving effectively for FE because you need to keep your exhaust temps up.

All that being said, I geneally like the way you think!

[slowmover]

Bear with me, this isn't as adamant as it may sound.

As to case-by-case basis the two I mentioned seem to be the ONLY ones, that, together produce changes in overall average annual fuel economy (working from a solid baseline and stock truck). The magic boxes only "may" produce an increase, typically in only one mode of driving: stop n'go. The timing advances make it easier to not hang shifts (manual) and make life a bit easier for autos. The "evidence" for steady-state fuel economy increases -- highway -- pretty well doesn't exist. (This understanding is taken from the main guy at the best known aftermarket Dodge tuner; all my wording, however.)

You may be the person to allay the concerns: solid mechanical baselined truck, highly extensive records, and the education to pull off a set of proper tests (given the exigencies of private life and budgets) once the parameters are clear to you. Hope you'll give us Dodge guys another piece of ammo to chronograph!.

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[Diesel_Dave]

slowmover,

Timing advances (almost always) increases engine thermodynamic efficiency--both transient & steady-state. There's not really any mystery about that. You can get the information from any basic engine textbook.

There are 2 warnings, however, about advancing timing.
1) If you take it to an extreme, it is possible to advance the timing too far. When this happens your FE will come back down. You'll also start getting black smoke. Back in the day (before we had to worry about NOx emissons) a rule of thumb for setting the timing was to advance it as much as you could until you started getting black smoke.
2) Be very careful about advancing the tuming significantly if you're going to be running at high loads (heavy towing, etc.). Advanced timing increases peak cylinder pressures. This helps your FE, but if you go too far you can cause mechanical damage. If you're not pushing the engine you don't have to worry about it because the cylinder pressures aren't anywhere near the limit.

FYI, I've done diesel tuning for years and if you want to increase FE the easiest thing to do (tuning-wise) is to advance the timing. Engine manufactures can't advance the timing that much anymore because the NOx emissions also go up.

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Here's a simple graph from an old research paper:
http://www.oliverdiesel.com/referenc...tiontiming.jpg

[slowmover]

Thanks, DD. I should have posted that there are DIY mods ("tone ring" on CTD) that are pretty well free, versus a $600 gizmo. I'm well aware of changing timing to more optimum specs (and you did a far better job than I would have in explanation).

The unanswered question -- as always with engine programming -- is what else is affected? Even subtle changes can have long term impacts that the short-term owner (5-7 years) has no "reason" to care about (as his purchasing decision is emotional, with only a nod to potential consequences) as the truck is long gone once issues of wear & tear begin to surface.

Diagnosis of problems is kept within bounds as aftermarket gizmos add complexity to decision trees. Of course, there is no in-depth explanation by the aftermarket as to what parameters are changed, and we are in the dark with -- at best -- SWAG to work with. The "improvement" may wind up costing more (much more) than the purported savings; thus my cautionary stance. (We are to put ourselves, IMO, in these shoes: my job has disappeared, my wife is now chronically ill and the need for the truck has become paramount . . . . )

Having owned many "old" vehicles [daily drivers], and driven 3/4-million mile trucks one is always stymied by a previous owners attempts at "improvements" . . from which I do not except myself. The dead stock vehicle tends to have the longest life for the lowest cost. A very high tendency. A 50k mile reduction in useful vehicle life is no small consideration (as an example). A truck has no substitute for itself as does a car as it is much more than private transportation. It is central to the income of the owner (whether an individual or a group). The loss of an otherwise good truck is little different from having to search for a new employer when understood properly.


EFI Live is a new (to CTD) program that allows the user to tailor engine operation profiles. Could be one will do more or less hypothetical damage, but at least the inputs would be clear during experimentation. At least I know whose tail to kick if things go wrong.

Looking forward to this thread progression. There is a dearth of genuine interest in fuel economy in diesel pickup trucks.
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[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.