Hypermiling tricks for an older fullsize gas truck?

Discussion in '4x4's, SUV's and P/U Trucks' started by carrmann, May 19, 2011.

  1. carrmann

    carrmann Well-Known Member

    Has anyone had any luck improving the fuel mileage of an older fullsize truck. in my case a ram specifically. this truck is setup as a tow vehicle (4.10 gears, helper springs, long bed, full bed cap), and Im currently getting apprx 13 ish mpg per tankful (varies depending on various things. it also has a 36gallon gas tank.

    Any tips on what I should/should not do? it has 170k miles on it so i dont want to do anything to hurt it. im worried that doing the N coast, then back into D may hurt the trans... anyone have input for that? same with shutting the motor off when coasting... I dont want to cause more repair bills than I save in gas if you follow.

    i will be using an ultragauge on it in a few days that should help me somewhat in seeing what does/does not improve the mileage.
  2. Right Lane Cruiser

    Right Lane Cruiser Penguin of Notagascar

    You'll be fine with shifting back and forth between N and D while the engine is running. Try it at lower speeds first to see if the transmission needs a little bit of rev matching to get engagement to smooth out and don't stomp the accelerator pedal immediately after shifting to D -- you want to give the software and hardware a short interval to figure out what it should do first.

    Don't coast with the engine off with your automatic transmission -- most automatic transmissions are lubricated by a pump which only runs when the engine is on. A short distance (a few vehicle lengths a low speed) would be okay but you would quickly wear through any remnant oil film if you tried it for any significant distance or speed.

    Your truck has terrible aerodynamics, lots of weight, a large displacement engine, and short gearing -- to improve the mileage you'll need to keep the speeds down, try to stay in torque converter lockup to minimize losses in the transmission, avoid stopping whenever possible, and avoid idling as much as possible. Once you've got your Ultragauge hooked up set one of the readings to gallons per hour. Watching your consumption rate you should be able to figure out how much fuel it takes to start the vehicle, then you can calculate how long it takes to spend that amount while idling your vehicle. Once you've determined that, turn the engine off anytime you'll be stopped for longer than that amount of time. As long as your engine is all warmed up the starter will see almost no wear from a quick spin to get things running again. Most starter wear is caused by excessively long cranking sessions which cause heat -- it doesn't take much to start a warmed engine and many of us have been doing this for multiple hundreds of thousands of miles on original starters with no issues because of this. Do keep an eye on the 12V status, though -- you don't want to get stuck somewhere because you don't have enough juice to start up again!

    Good luck and keep the questions coming! Chart your progress too so that we can offer further advice as you try new things.
    Last edited: May 19, 2011
  3. carrmann

    carrmann Well-Known Member

    filled it up from halfway today lmao. cost 74.61 to go apprx 260 miles. the car was empty, cost about 60$ to fillup and went 600 miles.

    def. gonna put more effort into getting good mileage out of the truck!

    i will hold off on shutting the motor off then right_lane_cruiser then, thanks for the tip! I will only shut it off when stopped for more than a few secs. i think the ultragauge will help me a lot with it as I have no gas mileage feedback with it until i fillerup.
  4. npauli

    npauli Well-Known Member

    All the usual hypermiling tricks work for big old trucks too. I can't tell you the particulars to coaxing better efficiency from your powertrain, but I can tell you how to drive so that the powertrain doesn't have to work as hard:

    - keep that big thing moving. That means planning you route, anticipating traffic and lights way out in front of you, and generally doing what you can to keep use of both pedals to a minimum.
    - because the aerodynamics are so horrible, driving a little slower can make a big difference.
    - air up those tires. You've probably got load range E tires with 80psi max on the sidewall. Higher pressure = lower rolling resistance. Beware, theres some tradeoff w/ tire wear and handling. Too much pressure and the tires wear unevenly, giving shorter life. Too much pressure and it's easier for a bump to get a tire to slip. FWIW, I run about 75-80 in front and 70 ish in the back (less weight on the rear axle).
  5. carrmann

    carrmann Well-Known Member

    i have the tires aired up to max sidewall i believe. i think its 60front and 55 rear.

    Cant plan my route. There is no 'other way' to go.. at all. only deadends. I have one route, and its the same as 20k other peoples route lol. 2 lanes each direction.

    I am doing my best to keeping it moving, and I dropped my top speed from 70mph (keeping with traffic), down to 55mph, 60mph downhill(not very many in florida).

    I thought airing up the tires didnt affect treadlife anymore do to steel belted radials design??
  6. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Usually true, but some truck tires still bulge and wear in the center.
  7. carrmann

    carrmann Well-Known Member

    hmmm ok. well, its really irrelevant on it anyways. Its had the front tires on it for 8 years, and the rears for about 5 haha! they do not match lol.
  8. EVuser

    EVuser Well-Known Member

    If you can plug in a ultra gauge via a OBD port it doesn't meet my definition of a OLD truck.

    DWL & DWB, are pretty low hanging fruit. In most heavy vehicles acceleration takes a big bite out of the gas tank so the ultra gauge will give you a look at how to minimize the guzzling.

    If you have a lot of extra stuff in the vehicle getting the weight down helps.

    Over at ecomodder.com you might find some truck mods that might increase the mpg by reducing the drag. At current fuel prices a little bit spent for a % or two can have some pay back.

    Keep a daily trip log with the new gauge and try to beat the best mpg on those segments you do all the time. :flag:
  9. carrmann

    carrmann Well-Known Member

    yea.. old would be 70s era like my old 71 ram lol. miss that truck!! I got 18mpg with it lol. sb, rc, v8 3spd auto with a 2bbl carb

    only 'excess' weight would maybe be never fill over a half tank since its got such a big tank? thats a lot of weight lol. the cap i think makes up for weight by improving aerodynamics slightly.
  10. EVuser

    EVuser Well-Known Member

    18 mpg might be well above the norm.

    If you mean a full size cap, like in "camper shell" cover vs a tonneau type I think they are worse. Your likely right about the flat tonneau type being better and certainly useful for securing things.

    I find the best way to save gas on my vintage 5.9L B200 is to only use it for things the gas savers can't do. If it isn't running a gallon lasts a long time. I've now had it long enough that it is a family member and neighborhood landmark. It does do better with a front air dam. But speed reduction is easily the most beneficial. Big flat mirrors seem to hurt about 1 mpg above 60 from my experience.

    Those big tanks are nice for getting between "cheaper" stations sometimes. But the weight is real. Having hiked a lot of mountains I frequently think to myself how I wouldn't want to pack this up hill as I load things into my vehicles. :flag:
  11. carrmann

    carrmann Well-Known Member

    got the ultragauge today... calibrated it once. will continue to calibrate for accuracy. going to test the gallons used tomorrow as well, and speed/mileage with my gps instead of using trucks speedo/odometer.

    ultragauge says 18mpg average over a 14.7 mile trip.

    statistics are: 14.7 miles, .82gallons used, which comes out to 17.92xxxx mpg. Avg speed of 38.1mph.

    if it seems accurate tomorrow after I fill it up, and test the speedo/odometer with the gps and its close to correct I will redo my sig lol.

    of course this was ideal conditions. apprx 65* out, no traffic, only 3 traffic light (all the rest were blinking yellow lights... normally there are 13 on that route).

    only thing I did was practice smooth easy throttle control, shift to N when I anticipated a red light (or there was one). Max speed was 55mph.

    maybe there is hope for me getting the 17mpg avg Im hoping for!
  12. herm

    herm Well-Known Member

    Regarding tires, unless you need them for heavy load reasons you dont want truck tires.. they are usually bias ply and use up a bunch of gas, plus have wear issues if overinflated. Radials use less gas and have no wear issues.

    Do you need the cap?.. get rid of it and store it in the backyard, its not that hard to reinstall it, save a bit of weight there.. when you take off the cap take off the tailgate also, if possible.. much less drag and quite a few lbs in that chunk of steel. You can also ride around with the gate down or replaced by a net if you must.
  13. carrmann

    carrmann Well-Known Member

    sadly I dont have anyplace to put the cap. so its not an option to come off. i could take the tailgate off... but it would look pretty retarded lol and not sure it would save anything with the cap on. the cap is about 250-300 lbs, and is not easy to install/uninstall unless someone helps (i've done it alone, not fun).

    not sure if they are bias ply or not, I will check today though. wouldnt want to go buy the proper tires for it if they are bias ply though... it does occasionally tow heavy loads etc (cars, trailers, stuff in bed blah blah).

    since february, i've driven it 800 miles. so honestly investing the money to buy new tires for it would be kinda overkill ya know?
  14. phoebeisis

    phoebeisis Well-Known Member

    You've gotten plenty of good info here-seem to be doing very well.
    An 18mpg tank would be absolutely spectacular for any tank that wasn't pure hy.
    For reasons I'm unclear on the Dodge 1/2 ton pickups usually get poorer mpg than similar Ford or Chevrolet pickups.
    This trend might have been slightly addressed by Dodge in the last year or two.
    My 1998 Suburban-2wd 5.7- will get 18 mpg on long(15 mile) on one pure city trip that involves almost 7 miles of in the city interstate.

    Does your vehicle engine brake when you lift off-at 37mph? My Chevrolet has ZERO engine braking when I lift at 37 mph- it doesn't offer any engine braking until I feel a downshift at about 24mph.The transmission in effect disconnects from the engine and rear wheels
    I get the same mpg in D or N so I don't have to shift to N-I just lift off and glide.
    I don't know if your Dodge has this capability.
    Main things as other mentioned-
    1) Stay off the brakes
    2) Keep you hy speed down -60 or less if possible. I don't pulse and glide on long hy trips,(I use the CC on level hy) but I will d/c the CC and drive with load up hills overpasses bridges.
  15. carrmann

    carrmann Well-Known Member

    its actually a 3/4 ton with 4.10 gears. pretty sure I would do a bit better mpg wise with 3.73 or 3.90s etc. The motor they used for a long time, is an OLD design with very few updates. Changed it to fuel injection, and slightly upgraded the head design/cam design. Nothing spectacular. Its not a bad engine, just not very fuel efficient.

    I know the new dodges see in the 22-24mpg range pretty often with the 1/2 ton hemis. My coworker has one and gets 19mpg in city driving back/forth to work, and about 23mpg on the highway with it.

    Im pretty sure it almost constantly engine brakes, as it always feels like I have less drag in N than I do in gear.

    what load should I keep the motor at when driving with load? is there a magic number, or do I have to figure it out for my vehicle??

    The ultragauge has helped me out with my driving 'style' quite a bit by being able to see real world numbers change while I use it.

    does anyone know if the ultragauge has individual programs for different vehicles? or do I have to re set it up for each vehicle when I plug it in?
  16. FSUspectra

    FSUspectra Practicing true conservatism!

    You'd have to recalibrate it... but if you wrote down the calibrations for each, the switch over should be easy and wouldn't require you to keep running calibration tanks each time you switch.
  17. carrmann

    carrmann Well-Known Member

    newest fill up showed an improvement! pretty happy considering i had quite a few crappy trips (only a few miles) that never left open loop.

    hoping to see better after I seafoam the engine/etc. etc. it needs it.

    still.. went from an old average of 12.6 before this site to last tankful of 14.4mpg.

    if i can cut out the 'short' trips i think it would vastly improve my economy at least #s wise lol.
  18. FSUspectra

    FSUspectra Practicing true conservatism!

    Your 12.6 to 14.4 MPG is a 14% improvement. That really is excellent!
  19. phoebeisis

    phoebeisis Well-Known Member

    Carrman- right-Dodge finally started getting serious about FE with the Hemi's.
    The pre cyl shutdown Hemis got horrible city MPG.
    Since about 2007 they do much better.

    14.4 mpg is excellent.
    Too bad your vehicle has engine braking when you lift in D top gear , but since it is a work/tow type vehicle- 3/4 ton- it would be biased toward engine braking(safety save the brakes), not FE.Just put it in N like you do.

    14.4 is excellent for a 3/4 ton work vehicle.
    You have done the switch to syn oil and diff lube?(worth a .1mpg or so)
  20. carrmann

    carrmann Well-Known Member

    it actually does seem to 'coast' in OD over around 38mph , didnt see a change in my instant Mpg between od and shifting to N.

    went 63.7miles, only used 3.8g which works out to like 16.76mpg avg. this was 60mph top speed, stop lights/stop signs/medium traffic.

    seems i am improving my hypermiling skills in the truck lol. that was also with a passenger, and a new freezer in the bed.

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