Improving the JK fuel efficiency?

[Black_ZJ]

Quit your complaining, with the v8, 4.56 gears, and 35's I am very lucky if I get 14-15 mpg highway going downhill. Someone once said that if you can't afford the gas then you shouldn't have bought the vehicle.... I own 2 Jeeps and our 2 other cars that get 30 mpg, and so glad the Jeep will never be a DD. When I bought my first Jeep in 1999 gas was around 89 cents a gallon, I still have that Jeep and have added another Jeep to the mix knowing it gets poor mpg. But this is my hobby and how I relax, can't put a price on the peace and feeling of accomplishment that comes from working on your own Jeep and taking it where others only dream of.

With all of that being said, I am starting the hunt for a 94-98 Cummins to tow the Jeep to the trails with, the truck will almost get better mpg towing than the Jeep does empty.

[Septu]

Really? What's wrong with asking others to see if there's a way to save a few bucks? Good for you that your jeep gets 14MPG. Want a cookie? I get 15-20 depending on how I drive it, yet that doesn't mean I don't look for other ways to perhaps improve on that further. It may or may not be possible... but that doesn't mean I shouldn't at least look into it.

No need to be an ******* about it.

[DontBlink]

Having come from a performance car back ground with an in house chassis dyno i'll always be a fan of air intakes with a velocity stack(K&N for the jeep) and exhaust systems. my wife has a 2007 JK with just a K&N intake,when we bought the jeep average mpg was 19 on the jeep cluster and 19.2 on my calculator, that was a strip from Pittsburgh to columbus ohio via rt 70. after the intake almost the same trip from Pittsburgh to Logan Ohio 21.7 on the jeep cluster and 21.9 on my calculator(also via rt 70). around town we dont pay to much attention with since she only works 8 miles away and its alot of stop and go traffic and red lights.

On the dyno i never seen a vehicle lose hp with a velocity stack equipped air intake, but i seen gains as low as 1hp and gains as high as 12hp(this was at the wheels). so for the price id give that a shot.these are figures i have seen so thats my suggestion, everything else is down to weight and aerodynamics.

Im very interested in your trip also, as soon as i get my 2nd week of vacation from work my wife and I would like to take a 2 week trip just as you have planned but were still mapping out routes and sites. we'll most likely be taking my TJ instead of her JK.

[grecy]

Having come from a performance car back ground with an in house chassis dyno i'll always be a fan of air intakes with a velocity stack(K&N for the jeep) and exhaust systems.

On the Pentastar, this is more true than ever before for Jeep.
Ever wondered why the exhaust runners hang so low on the new V6? It's because sophisticated engines with VVT really, really, really benifit from tuned-length extractors. (Dave from AEV mentioned he thought it was good for 45 hp).
Further to this, the V6 really wants to breathe well, so an air intake will help things for sure.

I know this has been proven not to work in the past on the 4.0 etc. Remember, we're talking about a sophisticated computer controlled V6 with VVT here.
Jeep engines are no longer in the dark ages.

-Dan

As an aside, while it's not a Jeep engine, my 3.0 V6 with VVT, DOHC and 4 valves a cylinder from Mitsubishi gained 20hp and roughly 15 ft. lbs. of torque from a new air intake and tuned length extractors.

[irish1371]

there are a few tricks that help with jeep gas mileage, cold air intake, proper gears ect. The 2 biggest factors to me getting 22 on the highway with my 98 tj on 33" when all my friends get like 16-18?

a vacuum gauge and keeping the engine under 2k rpm. If you get use to driving my the vacuum gauge you will find you highest efficiency for your engine is almost always at it's highest vacuum rating while at cruzing speeds.

As far as the 2k rpm, try getting any returns out of a brick going into the wind, It seems that after 2k rpm I might as well count on getting 12-14 mpg but that's my jeep and every one is different. My friends are always amazed at my gas mileage

[JKJenn]

Thanks for all of the replies. I have not driven a lot and I think I have reached a manageable situation. first, most of my regular driving occurs in constant stop and go traffic, in hilly terrain and for short periods (Pittsburgh has the steepest street in the world.) That is going to suck the life out of my gas mileage and there sin't much that can be done about that.

Second, I have been trying Craig's advice out and reached a nice 16-17mpg highway last time. I am happy with 16mpg. I have noticed I get better mileage driving North to South versus East to West. I am guessing it is because our winds are usually from the west and I am often driving into the west. I also think my gas mileage should be higher when I hit the flat lands, just across the PA border in OH.

Thanks, again, for all of the suggestions.