Forum Discussion

x0054's avatar
x0054
Explorer
May 13, 2014

Better Gas Milage and Shift Lock on e-350 based RV?

Hi everyone!

We have a 21 foot 1994 Shasta RV based on a e-350 Ford with 460 engine. We are getting about 9MPG, maybe just over, on South CA roads. Any ideas on how to move that up a bit, maybe to 11-12 MPG? I read that maybe a wind deflector might help, to prevent the wind from getting trapped under the cabover bad. But googling around I have not seen anything. Is it worth it, and any links on what I could get?

Any other ideas?

Also, I am looking for some kind of way to lock the damn transmission in higher gears. The RV has a massive engine that isn't working hard at all when pushing the RV around. But any time we start climbing a steep heal, the transmission kicks down to what I am guessing is 2nd gear. It's quite annoying, especially considering that every vehicle I have ever owned since I learned to drive was a stick-shift, and I am not used to having some computer telling me what gear I should be in. Maybe there is a hack that can trick the transmission into not downshifting while a switch is toggled. Like a shift lock switch? Again, not sure if it's possible, but any ideas would be much appreciated.

- Bogdan
Class C
  • cgmartine's avatar
    cgmartine
    Explorer
    May 21, 2014
    You are not driving up hills with the cruise control on are you? If so, take it off cruise and allow the engine to come down to the next lower gear. You should not drive up hill as fast as you do on a straight away.
  • Harvey51's avatar
    Harvey51
    Explorer
    May 20, 2014
    I get about 4.5 km per Liter, which I think is 10.5 miles per US gallon with our E350, about 8000 pounds. It downshifts on hills for sure. And needs to.
  • x0054's avatar
    x0054
    Explorer
    May 13, 2014
    You guys might be right, torque converter may not be capable of taking the more load, but I am telling you, the way the engine feels, I think it could easily, without even trying, pull the RV up almost any hill in the 4th gear. Is there a way to perhaps connect a light to the transmission somehow so it would light up when the torque converter is locked. Just out of curiosity. I want to see when it locks up, and when it disconnects. Perhaps I can modify my driving style to get it to disconnect less often.

    I usually drive with cruise control set to 55mph, so I doubt the speed is a problem. I guess there isn't much of a problem, since from what it sounds like, my milage is right in the ball park. I was just hoping that I could get a little more :)
  • carringb's avatar
    carringb
    Explorer
    May 13, 2014
    tpi wrote:
    Those downshifts keep the torque converter cooler.


    X2 - The E4OD torque converter strategy does not keep the clutch locked in high gear under heavy load. I'm guessing the stock clutch just isn't strong enough to allow that. Once it unlocks, your trans temps will skyrocket. Lower gears reduce the heat generated by the T/C.
  • tpi's avatar
    tpi
    Explorer
    May 13, 2014
    Those downshifts keep the torque converter cooler. It is better for the mechanical gears to multiply torque than pouring a lot of heat out of the converter doing it.

    For overall financial perspective I'd say keep the speeds down, engine tuned, tires inflated properly, and buy gas at the best price. Beyond that sinking money and time into squeezing out the last tiny % probably won't give good returns. Your 9 MPG sounds in the ballpark as is.
  • ksg5000's avatar
    ksg5000
    Explorer
    May 13, 2014
    Drive slower and keep weight down by keeping FW tank at minimum and emptying gray/black water when departing camp sites.
  • garyhaupt's avatar
    garyhaupt
    Explorer
    May 13, 2014
    I had a '94 E 350 with the 460 and man, that is a good engine. I made a couple changes that improved the gas/distance but also really increased the power delivery.

    I installed a Banks air breather system. No big deal in cost or parts. Plus went to a K&N air filter.

    Then went to Red Line synthetic oil. This lets the engine run cooler.

    I also switched to using a NAPA Gold oil filter. Larger..more capacity. Runs cleaner.


    The biggest improvement came from switching to the Banks, everything else was a compliment to that.


    Gary Haupt
  • the_bear_II's avatar
    the_bear_II
    Explorer
    May 13, 2014
    Be happy with 9 MPG. Trying to do anything else will be costly with frustrating results.

    One of the best alternatives is to always drive at 55MPH. You'll see another 1 MPG at least.

    The worst thing you can do to an engine is to allow it to lug up a hill in top gear (waste of fuel and puts a strain on the drivetrain). The downshift will get you into a good torque range for going up a hill so you run more efficient. These aren't hot rods, even at only 21 feet that's a lot of weight you're carrying.
  • Calisdad's avatar
    Calisdad
    Explorer
    May 13, 2014
    I wouldn't mess with it. I have a '94 E350 Tioga and get 8mpg. Our best mileage occurs at 62mph and below.

    Have you looked into 19" wheels. I'm pretty sure there's a thread or 3 here on the subject.
  • jmcgsd's avatar
    jmcgsd
    Explorer
    May 13, 2014
    You're talking a 20% increase. I don't think it's going to happen no matter what you do. What speed do you drive? First thing I'd try is slowing down.

    I tow with a similar vehicle, a '91 F350. It gets 8-9 towing and maybe 11 when not towing. I also carried a truck camper on this truck for many years and it got about the same mileage as it does now when towing. I think that's he nature of the beast.

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