a higher performance ignition will help a little (MSD and others)

reduce rotating mass (lightest wheels and tires you can get, reduce weight of any other moving parts int he drive train)

reduce air resistance.....dont think you can do that easily...this is the biggest killer for jeeps.

 

Didn't even think about ignition. Does that really effect gas mileage? What about These air intake kits and airflow management systems? Even using a cone shaped air filter I have heard helps air flow. Now I know that better air flow adds horsepower but will increased horsepower necessarily help gas mileage? Would new aluminum headers help?

 

but will increased horsepower necessarily help gas mileage? Would new aluminum headers help?

Have I missed something over the years? I thought that aluminum was used for intake manifolds and steel used for exhaust headers.

Increasing horsepower, or torque, will not necessarily increase gas mileage. However if you use the performance increase to allow a gear change or larger tires, they you may get a gas mileage increase.
Basically an increase in gas mileage comes from turning the tires the same number of times using less gas, or more times with the same amount of gas.

With it burning oil then some of the bang inside the cylinders is not being used to turn the wheels.

 

A low restriction air filter will help, and you'll feel a power increase. Headers probably won't help, and a new ignition system will probably help, but won't ever save enough fuel to pay for the ignition. Like Greg said, the aerodynamics of a Jeep negate any kind of fuel mileage. I get around 16, but most get less than that. I drive like an old woman in order to get that mileage.

 

Most high performance add-ons aren't worth the power to blow 'm to hell. Look at the cost and see what they'll payback and you'll find, even with today's fuel prices, the cost is prohibitive. Also, most of these items are supposedly "performance" enhancing and that is a whole lot different than items that result in fuel savings. The Open exhaust and intake can help, but IMHO, even that is a crapshoot as it's cost driven.

The biggest thing you can do... is drive that Jeep at the lowest speed you can stand, and go lightly on the gas pedal.

You may be interested in this article from JP Magazine:

Save Gas! - Cheat The Gas Nazis
Fuel Economizers: Tested!

 

anyone here willing to chop and channel a jeep????

it'd be in the name of science for gas mileage studies (does that make it tax deductable?)

I think the channeling might reduce your tire clearance a little though

 

Its old and it burns oil and gets bad gas mileage, but damnit its my baby. I had it up on blocks for the past three months working on the exhaust and tranny system and clutch during free time and when I got it back all I wanted to do was drive. I appreciate the advise guys and I guess with these bad boys you just need to take the good with bad right. I'll work on the air system and when I do I'll let you all know what effect if any it had. The ignition is probably (from what I'm hearing) too costly to be a benefit. I do still have to do the rack n pinion though so while I got it taken apart I may just do that also.

Oh, and driving slow isnt me...oh well

 

I do still have to do the rack n pinion though...

are we still talking about the Wrangler here???

Oh, and driving slow isnt me...oh well

doesn't sound like mileage is all that important to you then. I use to have a hard time staying out of the throttle myself, but I found it easier on the wallet to lighten up on the skinny pedal.

 

Oh, and driving slow isnt me

Too bad. That's the only thing that will really save money.

When you're thinking about re-arranging the air intake think about keeping water out of it. I ran my air intake through the firewall above the battery. It will have to be in very deep water to get any in there. If you just suck air from high in the engine compartment it's fairly safe, but breathing hot air decreases the engine power. Getting it from behind a headlight is dangerous. It's real easy to nose into a puddle of unknown depth and get in that deep.

 

I recently found a most certain way to increase mileage. I slowed down 5 mph on my 30 mile commute. went from a VERY consistent 350 miles to a tank to now 400+ miles to a tank. This morning I just hit 3/8th tank mark and I'm at 325 miles on this tank. I'm looking at an extra 3.5 mpg on my ZJ with the 4.0L. that's about the best mileage increase I've ever done... short of a different vehicle.

 

It's easy - Buy every gimmick JC Whitney offers that "improves mileage."
But be careful, using too many is a pain too - you have to stop every so often to drain fuel out of the tank.

Probably the biggest improvement in economy for the money is getting the timing curve correct. If it's not igniting the air and fuel properly it's wasting fuel.
You want it as efficient as possible.

Higher efficiency also lowers emissions and improves power as well.

 

Besides having the timing correct and carb set up correctly....about the only things that will help are:

1. Weight - the less weight you are trying to move around, the less gas you need.
2. Speed - Slow down
3. Acceleration - Stop and go traffic kills MPG...start off slower and use less gas.

Low restriction air filters....do nothing for MPG. The amount of gas going into the carb is determined by the amount of air going through the ventury...a low restriction air filter just lets more air go through the carb.

Don't forget, the jeep is about par to pushing a 4'x8' sheet of plywood through the air.

 

"""""Low restriction air filters....do nothing for MPG. The amount of gas going into the carb is determined by the amount of air going through the ventury...a low restriction air filter just lets more air go through the carb.""""

Unless of course the restriction is enough to create a vacuum inside the carb environment, then it helps to "suck" more gas down, more than needed.
That includes the bowl vent ent area and the area where the bleed holes are. They should be kept as close to atmospheric as possible.

 

I'm getting about 21 right now on my TJ, about 95% highway driving in my daily commute.

I drive slow on the highway, about 65.

In my opinion, anything that reduces "pumping loss" for the engine, will increase MPG. Reducing air filter drag, air intake tube drag, headers, high flow cats, high flow exhausts, etc. And synthetic oils in the diffs are supposed to help. Question is, will any of those improvements be measurable.

Here's a picture of a TJ from Turkey. Note the cool bumper air deflector. I wonder if stuff like this helps mileage. If it improves air flow over the Jeep, I'd guess so. I wonder if one of those goofy hood-mounted air deflectors would help too.

Pete

 

Do an injector swap. I think you only have the one nozzle injectors. They're probably all ill matched for flow. You can try Gumout Regane Complete FSC or something like Amsoil's PI and see if it helps. I just went to 4 nozzle Liberty injectors and the drivability was substantially improved over the single nozzle originals. Fords (mostly) appear to be 4 nozzle types. You surely have Design II with the Design II connectors (rectangle) but there are some Design III's (pencils as opposed to chubbies) that also have the right connector. The length is the same.

Mine must have been really bad. I can actually walk out from the shift light shift points with 33" tires. Normally 5th gear was 50mph+ ..but now 4th is 30 mph.

..but if you're hammering it anyway ...<shrug>

I have a Warn lock out hub kit and synth in the diffs and whatnot. While they appear to reduce drag, it really doesn't seem to equate to mpg.

 

Boys, boys, why stress about it? I'm pretty sure none of us bought our jeeps for the great mileage they get. My jeep came with the 6 banger, then came the 304 and now I'm running a 360. In all the years I've had my jeep I have never once checked the mileage. I don't need to know, I don't WANT to know. As said, there ain't much you can do about it anyway. Maybe we can start a new fad running those good looking donut spare tires on the street on our jacked up jeeps! Oh man, just the thought of that makes me ill...

 

i recently re-read an article on the 2.8L diesel 4 door jeep released in the UK....says it got 29 MPG.....almost 2x what US gasoline jeeps get.....but diesel is more expensive, though not 2x as expensive....

I wont buy a new jeep until they get me a diesel with good MPG here in the US. I drive too much for a Daily Driver jeep otherwise.