2000 Jeep Wrangler Swaping out 4-cyl for Better

Aww you don't like the AMC 150? (lol I have a 2.5L Wrangler) I am not sure what kind of gas milage you are looking for but 25+ is out of the question. Before you consider doing anything you need to check with your state on emissions requirements and if they require you to have stock emissions equipment on the vehicle. (or someone who is willing to turn a blind eye to you and hand out an emissions sticker) Now if you just want to swap it out for the chevy 350 SB then it can be somewhat difficult. If you are going to do this then you need to also change out the transmission. Go with the GM NV4500 because it is literally indestructable. Depending on whether you want fuel injection or carburated things more or less simple. You will need to remove the ECU and all the components and replace it with something suitable to the new 350 SB. Several aftermarket companies sell entire engine management kits for engines. Try JEGS automotive and they can get you a crate 350 SB, engine management system and everything else you need. You will need to obviously change out the motor mounts, radiator, exhaust system and the stock ac compressor (unless you can find a bracket) just to name a few. You might consider a different rear end (dana 44) and a larger fuel tank.

Can I get better then 17 mpg? If I can, what do I need to have and how do I do this? Thanks, for the info I did contact the engine factory I think the engine swap maybe take awhile to pay for and due.

You can probably buy a power programmer for the computer. Change the stock muffler to the flowmaster super 44. Change out the stock air filter or the entire air cleaner for a k&n. Try Quadratec they offer tons of stuff you can look through for your jeep. Jet offers computer chips for the later model 2.5L so you might want to look into it. You can also change out the map sensor and cps sensor as well as the throttle body from Rock-It. The exhaust header can be changed out for a borla type system. Purchase an MSD 6A Capacitive Discharge ignition, a set of 8mm wires and some irridium spark plugs. Changing the ring and pinion gear can give you a greater mechanical advantage at the rear wheels if you are looking for more power; however, you will sacrifice some fuel economy. All of those together will push the car into the 22+ mpg range. Lol your talking about moving a brick through the air so unfortunatly the car needs to be streamlined for good gas milage. I doubt you will get more than 14-16 with a V8.

I'm new to the working on vechicle world... Literally... So if I do all that you sugusted I can come pretty close to or better with 22mpg. I'm just trying to make sure, I'll take gas milage over all else. Thanks I'll still besble to play in the mud right?

And got get stuck like this guy?

You will probably gain anywhere from 10 - 30 bhp from these upgrades as well as better gas milage. If you don't want to get stuck in the mud then the key there is torque. You want the highest ratio gears possible in the mud. A ring a pinion change will ensure this along with mud terrrain tires for traction and a lift kit to keep the car from becoming too bogged down in the mud.

Thank you for helping my dad, I don't want to be stuck. I have enough mud in my drawers