How do I up the MPG's on my Willys Jeep???

Discussion in 'Flat Fender Tech' started by mikec4193, Apr 4, 2012.

  1. Apr 4, 2012
    mikec4193

    mikec4193 Jeepless for first time since 2007....

    Mechanicville ny
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    Hi Everyone

    I have 3 olds smelly Jeeps that are all bascially in stock configurations. I am in the process of redoing a number 3 which is a 1947 CJ2A and it has been fun so far (grind cut weld...grind cut weld...grind cut weld). This little truck supposedly weighs in around 2,200 lbs and it is a 4 cylinder (with those 2 items listed it should be great on gas). I have heard stories about how bad they are on gas. So does anybody know where to get lower gear ratio's so I can drive this thing.
    I dont need anymore Willys Jeep yard art (2 of my Willys are running lawn art) and with gas sitting at $4.22 a gallon in my neck this morning I wont drive it if I cant afford to put gas in it. I want something I can drive to work (22 miles a day).

    I know nothing about Willys Jeeps except I like the way they look and they won us our freedom during WWII.

    Any insight would be greatly appreciated.

    MikeC
     
  2. Apr 4, 2012
    garage gnome

    garage gnome Rust polisher Sponsor

    Western MA
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    An OD will greatly improve it. With my '53, I get an average of 15-16 MPG, thats with the L134 w/ carter carb, T90, D18, OD and 5.38s. It also depends on the terrain. Where I live, it is very hilly. My milage isn't so good around here. When I venture off the mountains, to the flat lands, I'll get around mid-high teens, about the same as my DD TJ.
     
  3. Apr 4, 2012
    JeffsJeep04

    JeffsJeep04 Member

    Menomonie, WI
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    Pull it with a diesel truck?

    Seriously though, while it's a light weight vehicle with a tiny motor, the motor isn't the picture of efficiency. I'd say 20 is about as good as you'd ever get with one, with everything perfectly in order.
     
  4. Apr 4, 2012
    oldtime

    oldtime oldtime

    St. Charles,...
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    Yeah but another main concern is that wind resistance is VERY poor.
    So basically the slower you drive the better the MPG. Drive as slow as 30 MPH for best MPG.

    The 25% O.D. is absolutely the single best improvement to the gearing.
    Otherwise you will gain little without changing over to an engine with maximum torque output at a higher RPM.
     
  5. Apr 4, 2012
    68BuickV6

    68BuickV6 Well-Known Member

    Chino, CA.
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    OD.

    Other than that, you're looking in the wrong place for great mileage IMO. Driving a Jeep is like driving a brick. R)
     
  6. Apr 4, 2012
    ErksBurgMN

    ErksBurgMN 200$ Jeep

    Grand Rapids,...
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    Remove the top, fold the windshield down.....wear safety glasses for the bugs.
     
  7. Apr 4, 2012
    jwjeep60

    jwjeep60 in process

    Sedalia Mo.
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    16 mpg is my personal best in the jeep.
    a jeep liberty v6 gets 17mpg
    my s-10 gets 20mpg on a bad day, if it had a 5 spd it would be 25 to 30mpg,

    if you want an eco jeep, never put the windshield up, ditch all the 4wd components, replace with a modern (fuel injected, high compression) 4cyl and 5spd 2wd trans, while driving as slow as possible in the highest gear.

    it is the sad truth; you can't go anywhere, do anything... without buying lunch.
     
  8. Apr 4, 2012
    homersdog

    homersdog Tulsa, Ok Sponsor

    Tulsa, OK
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    1.0 Only drive downhill.
    1.1 If you live in the middle part of the country (rectangular states), only drive with a tailwind.
    2.0 Ride the bus.
     
  9. Apr 5, 2012
    mikec4193

    mikec4193 Jeepless for first time since 2007....

    Mechanicville ny
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    HI Everyone again

    So does anybody know of a company that sells gears so I can at least re-gear this thing so I can drive it??? I wont really use it off road or to tow anything at all. I am not a real true Jeep guy I just want something I can drive to my jobs which is a paved roadway.

    Any help would be greatly appreciated.

    MikeC
     
  10. Apr 5, 2012
    garage gnome

    garage gnome Rust polisher Sponsor

    Western MA
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    IMO, you'll want the 5.38s for the hills....
     
  11. Apr 5, 2012
    mb82

    mb82 I feel great! Sponsor

    Charlottesville Va
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    Yeah I would not change the gears much, and the price of changing gears can buy A LOT of gas when compared to the change in mileage would be. Face it old JEEPs don't get good mileage.
     
  12. Apr 5, 2012
    duffer

    duffer Rodent Power Sponsor

    Bozeman, MT
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    What everyone says about getting an OD. Forget gears, the 5.38's and the OD will put you someplace around right where you want to be and for the cost of 2 sets of gears and setting the diffs up, I don't think there will be much difference in cost even if you purchase a new OD. You might coax a little bit more mileage out of it with a high compression head and headers but not likely a cost effective solution. Also, keep it light and stay with skinny tires.
     
  13. Apr 5, 2012
    Corveeper

    Corveeper Member

    Chanute, Kansas
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    Running stock points ignition?
    I’ve found a couple of MPG on a few different engines by adding a good CDI box, like an MSD or Mallory but there are plenty of others available, and using the stock points to trigger it.
     
  14. Apr 5, 2012
    F Bill

    F Bill Member

    Abilene, TX area
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    Trade the CJ for a DJ drivetrain... 2WD and light.. Or do your own, install a postal front axle and a Toyota/Nissan/Pinto OHC modern engine and 4 or 5 speed, coupled to the Postal rear axle in the right ratio. Ya get flatfender looks, and modern reliability and MPG. Still have the aerodynamics of a billboard, but.... not much you can do about that. The ultimate would be a diesel conversion...but not many around to pick from. And they are spendy.
     
  15. Apr 5, 2012
    nickmil

    nickmil Super Moderator Staff Member Sponsor

    Happy Valley, OR
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    My question is what are you getting now? Without a basis for comparison hard to say if what you are getting is normal or not.


    Sent from my iPhone using Tapatalk
     
  16. Apr 6, 2012
    mikec4193

    mikec4193 Jeepless for first time since 2007....

    Mechanicville ny
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    Hey Nickmil

    I am in the process of rebuilding a 1947 Willys Jeep flatfender. It doesnt run yet but I dont wanna have this thing sucking me dry as far as gasoline consumption goes. My 1960 Willys truck will idle for 20 minutes on a gallon of gas. This is not acceptable in my world. I work two jobs now to support myself..I dont want to have to get a 3rd job just to afford gasoline.

    Still not sure how you guys really do afford these things yet.

    MikeC
     
  17. Apr 6, 2012
    nickmil

    nickmil Super Moderator Staff Member Sponsor

    Happy Valley, OR
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    To be blunt and honest if fuel economy is that much of a concern I'd consider a cheap commuter car for daily driver duty. Unfortunately these vehicles just aren't fuel efficient with highway driving no matter what you do. Use the Jeep for fun. Plus, you don't have to worry about getting to work if /when the Jeep breaks down. I used my Jeep as a daily driver for several years so speak from experience.
     
  18. Apr 6, 2012
    mb82

    mb82 I feel great! Sponsor

    Charlottesville Va
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    I agree with Nick.
     
  19. Apr 6, 2012
    duffer

    duffer Rodent Power Sponsor

    Bozeman, MT
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    3x. There are two big things working against you if you want to use a stock flatty or early CJ5 for a commuter:

    1) you have the most advanced engine technology available-for 1925. The combustion chambers and low compression were designed to burn low octane and CHEAP gas and there isn't much you can do about it short of an engine swap.

    2) the vehicle was specifically designed for rugged terrain. On-road high (in a very relative sense) speed travel was not part of that design, nor was being highly efficient.


    In short, many of us ask a lot more out of these old machines than they were designed and built for and if you want more, you need to redesign and rebuild. That takes a lot of time and money, or a really lot of money if someone else is going to do the work. Just about any modern engine (execpting maybe 360/401 AMC's) will get better mileage, including V8's with 3 times the displacement.

    Otherwise, you just need to accept them for what they are and use them accordingly. No silver bullets.
     
  20. Apr 6, 2012
    oldtime

    oldtime oldtime

    St. Charles,...
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    We have 2 intertwined but different concepts here; let us not confuse them.

    EFFICIENCY vs. ECONOMY

    Actually the 134 Willys engine is an extremely fuel efficient design.
    It's exceptionally undersquared design promotes a more thorough combustion of the charge.
    That said: it is certainly not an efficient design for todays economy driving at relatively high road speeds.

    Here is the main concern...
    The 134 engine will burn 66 octane gasoline (uncracked petroleum) as efficiently as 87 octane.
    It is not economical to increase the fuel octane to 87 when 66 burns just as well.
    Therefore potential energy increase from higher octane is wasted due to the low compression ratio.
    This is exactly why a compression ratio increase yeilds the best results for the effort involved.

    I am driving an optional stock CJ-3B as my one and only vehicle.
    It is certainly not the most fuel efficient vehicle on the interstate.
    However it is very economical for me to operate it.
    The main cost besides taxes, tags, gasoline, grease and oil is the occasional machining of the engine.
     

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