Idea to get better gas mileage...

[Serious Johnson]

When my '83 Wagoneer was stock and in pretty good shape it got slightly better fuel mileage at 75 MPH than at 50 (around 13 MPG @ steady state for both). There's a lot of torque converter loss with those goofy old slushboxes, turning power into heat, and it's generally worse at low revs. Aero on a Wagoneer is really not horrible -- smaller frontal area than most modern SUVs and a pretty decent shape, relatively.

I can't say exactly what got mine to 18-20 MPG because I did a lot of stuff at once. My guess is that the manual transmission swap accounts for most of it, followed by custom GM TBI. Properly integrated electronic fuel injection is not just an electric carburetor -- that would be fuel injection with a bad O2 sensor or the cheap kits without ignition control. The ability to monitor and adapt fuel & ignition curves is huge, especially if you drive where there are significant elevation changes. If you go farther, as I did, increased compression ratio contributes to efficiency, and can be reliably exploited with the precise control that good fuel injection affords and a little judicious re-shaping of the combustion chambers. An LS engine would be still better, but hell, everything is better with a small block Chevy in it.

S.J.

[PlumCrazyChris]

Right from the factory, these rigs got bad mileage.... 11 mpg

https://www.fueleconomy.gov/feg/noframes/8489.shtml

I sold my 79 Cherokee 360 for an 83 EFI 258 Cherokee. Same mileage.

I asked the other day if anyone that did a LS swap had any mileage results and everyone basically said it was the same. I seem to remember some years ago that someone at BJs swapped an LS into a Cherokee and was saying they were getting 20 mpg...

My 98 Ford Ranger 4x4 with an 5spd Auto 4.0 MPFI only got 15. I can't imagine these will ever get much more than that.

That said, a new Chrysler 300 with a 5.7 can get between 16-25 mpg and weighs almost as much... but has better aero and shuts off 4 cylinders.

[Don S]

..

Our 1981 360 2- barrel Wagoneer got 17 plus mpg on a 3000 mile trip through the Colorado mountains from Ft. Worth. The 1981 was one of the few (prolly only year) that the TF 727 had a lock-up Torque converter. Normal driving over 40 mph was direct drive.

Good Luck.. Don S..

BTW... Drive easy like you had an egg taped to the gas and brake peddles.

[FSJunkie]

Doesn't matter a whole lot what engine is powering it, you're still pushing a brick through the air. Aerodynamics are your biggest sucker of fuel on these for the highway. Their high weight isn't really a factor on the highway, it's a factor around town because you're trying to accelerate all that mass. That's the second biggest sucker of fuel. Together they kill the gas mileage.

The AMC 360 is actually a pretty efficient engine. It just has a lot of work to do.
Mine got 14 MPG on my latest road trip at 60-65 MPH. That's exactly what my parent's 2003 Dodge Durango that was following behind me got too, and it's a Dodge 5.9L with EFI, overdrive, and all the "modern" whistles and bells.

So you're just screwed. It's the price you pay for owning a car that is shaped like a box. Modern cars are all shaped like bubbles for a reason, which makes our boxes look cooler.

[ZackN920]

hmm, then why does my 'burban get decent mileage for it's size? If I'm driving on flat land, it's not uncommon to get 18mpg on the highway, and on average-around 12 in town. That thing weighs a good 1k more, and is as "bricklike" as the Wagon.

IDK, but I'm thinkin it would be better with an overdrive and re-gear for the overdrive... along with a locking torque converter. That'd get ya better/easier acceleration around town too, and thus better in town mpg.

I don't see how the 360 (in stock form) could be considered "pretty efficient" though. With all the emissions, it's choked to a weasy 145HP. Torque is all right, and gets ya going, but if it made more power, it would be easier for it to move the vehicle. If it's easier for it, then its more efficient.

[FSJunkie]

I think you'll find a lot of people on this forum who agree with you, which is why I am not going to argue this any further.

The topic of efficiency and performance on stock 1970s and 80s engines is a soapbox I tend to preach from, and being an unpopular view around here, stepping onto that soap box usually doesn't end well for me. It tends to bring the wrath of the entire forum down on my head.

So I'll just excuse myself now. Bye everyone.

[Locked and Loaded]

Buy a HOT cup of coffee. Place it between your legs. Pull the lid off. Fuel mileage automatically increases. It's magic.

[Locked and Loaded]

I think you'll find a lot of people on this forum who agree with you, which is why I am not going to argue this any further.

The topic of efficiency and performance on stock 1970s and 80s engines is a soapbox I tend to preach from, and being an unpopular view around here, stepping onto that soap box usually doesn't end well for me. It tends to bring the wrath of the entire forum down on my head.

So I'll just excuse myself now. Bye everyone.

Don't give up the soapbox Matt. There are a few of us still around that agree with you.

[jsinajeep]

Matt, I am with Jeff on this.^

[yossarian19]

This is an old thread but I'll beat a dead horse. Hell, it's the last thing I'm going to do before i put the laptop down and hit the books - so let me rant a little...

These rigs are bricklike but this does not mean they can't do better on the highway. They are also heavy, but ditto, they can do better in town. Heavier, larger vehicles with more modern technology are getting better mileage. A few key differences, though:

Overdrive transmission. Highway mileage demands an overdrive that gets used, so you need axle gears somewhere in the 3.xx range because in the 2.xx range you just drop to third anyway. I'd suggest 3.55 or 3.73 as the sweet spot.

Newer stuff tends to sit lower in front and have some sort of an air dam. You could duplicate this but at the cost of Jeep-ness.

EFI. Throttle body injection is great and it's what I'm building but MPFI is just plain better. Edelbrock has a lock on aftermarket kits but if you can come up with the know-how, you could put coil on plug ignition and MPFI on an AMC V8 using a lot of junkyard parts. You'd be into it for less than the Howell TBI kit.

Parts list: XJ fuel tank (or the blazer saddle tank), 5.3 coils, wires, harness & injectors, older chevy MAP IAT & CTS sensors, XJ auto trans & controller, Ebay some injector bungs & fuel rail stock, add an Edelbrock Air Gap (injector bosses cast into this one, not the performer or torker) manifold and a Megasquirt II or III controller... you're now low brow but high tech.

A TBI Blazer with AW4, weighing similar to our SJs, is rated ~3 mpg better than our rigs. The next generation Tahoe with the Vortec MPFI I think is 1000 lbs heavier and still gets better mileage yet.

I don't want to go nuts, here, but I honestly think that 14 city and 18 highway should be doable with these rigs. With a 4.0 / 4.2 hybrid (4.6 liter) I6, you might do a little better on the highway.

[jarhead_jeeper]

The original question was asked about a year ago but I suspect people are still interested to know the answer. The original question:

Has anybody bolted in one of the newer (1993 onward) 727s into a GW and taken advantage of the overdrive? I keep thinking with all my highway miles that 4th gear might really increase mileage.

I can't answer that directly because I have not done that.

Doesn't matter a whole lot what engine is powering it, you're still pushing a brick through the air. Aerodynamics are your biggest sucker of fuel on these for the highway.

I'm relatively new to this forum as far as posting goes but I will have to disagree with the first part of this statement. I believe the engine used does matter.

I had a 1969 M715 that I re-powered with a naturally aspirated 6.2 diesel engine. I used an adapter from Novak and the rest of the truck was stock. I consistently got 16 mpg with that truck but it fits perfectly with the second part of that statement. Since my top speed was only 45 mph I could not take it on the express-way to test the mileage there. I'm guessing since it didn't get driven fast aerodynamics were not a major factor.

I currently have a 1968 M715 that I have re-powered with a turbo charged 6.2 diesel. It also has a NV4500 5 speed manual transmission.

I don't have a working odometer so I can't measure fuel economy yet but I'm optimistic that I will be getting at least the same mileage as before and hopefully better. This trucks transmission will allow me to do 60 mph so I will be measuring mileage as soon as I get a speedometer/odometer functional.

I doesn't really matter to me much though. I'm not "worried" about fuel economy. It's really just a curiosity. I'd like to have an idea how far I can travel on a tank of fuel.

[Mikel]

The original question was asked about a year ago but I suspect people are still interested to know the answer. The original question:



I can't answer that directly because I have not done that.




I'm relatively new to this forum as far as posting goes but I will have to disagree with the first part of this statement. I believe the engine used does matter.

I had a 1969 M715 that I re-powered with a naturally aspirated 6.2 diesel engine. I used an adapter from Novak and the rest of the truck was stock. I consistently got 16 mpg with that truck but it fits perfectly with the second part of that statement. Since my top speed was only 45 mph I could not take it on the express-way to test the mileage there. I'm guessing since it didn't get driven fast aerodynamics were not a major factor.

I currently have a 1968 M715 that I have re-powered with a turbo charged 6.2 diesel. It also has a NV4500 5 speed manual transmission.

I don't have a working odometer so I can't measure fuel economy yet but I'm optimistic that I will be getting at least the same mileage as before and hopefully better. This trucks transmission will allow me to do 60 mph so I will be measuring mileage as soon as I get a speedometer/odometer functional.

I doesn't really matter to me much though. I'm not "worried" about fuel economy. It's really just a curiosity. I'd like to have an idea how far I can travel on a tank of fuel.

Very cool. How is the power in both trucks?

[jarhead_jeeper]

The n/a 6.2 was pretty anaemic but it was reasonable. The turbo is better but still nothing near your Cummins powered truck. The biggest difference is I can now maintain speed on grades without down shifting and revving the thing up so high.

I have not turned the fuel up at all and I don't generally get above about 5 pounds boost.

I'm fairly confident a turbo'ed 6.2 in a Wagoneer would be a nice boost in fuel economy and probably be a very small increase in power over a stock AMC 360. It should be fairly easy too.

[JPSwapMohn]

Not sure it helps the OP, but I did the LT1/4L60e swap a decade or so ago. I went to 4.10 gears at the same time. When all was working well, I was easily in the 17-19mpg range before the trans started acting up. I would guess the folks running the 5.3 are there or a bit better as the LS is a much more refined design and far less complicated than the LT of 94-96 was/is.

When I went to the Golen engine w RV cam, 1.7 rockers, etc. I never really looked at mpg again. I do run lockout front hubs and a np242 now, but the rig hasn't been on the road long enough since then to assess improvement.

Again, I would have to assume the 5.3 guys are doing better.

[jeepman1]

Amen