Choosing An Engine To Swap Into Your Jeep

Unless there just happens to be a complete engine and transmission, wiring harness and computer as well as all the necessary adaptors neatly tucked away in a corner just waiting for someone to come along and put it all together, choosing an engine to swap into a Jeep should not be based on what happens to be laying around the garage.

Although practically "any" engine can be made to fit into the generously sized engine bay of a Jeep, there is more to consider than just whether or not it fits into the hole. In the image at left here, it may not look like there is much room for a V8, but once the 4cylinder is pulled out, you'll see that there is plenty of space available.

Your States' Emissions Laws: 

One of the most important factors to consider before making any decisions on which engine to use for a swap into a Jeep is your states' emissions laws. Different states have different emissions laws, and swapping a different engine into a vehicle has emissions requirements that will need to be adhered to. If the new engine is going to be from a "donor" vehicle, and if you plan to register or sell your Jeep after the engine swap, then knowing your states' emissions laws will narrow your choices to finding a donor vehicle down to just several "qualified" candidates. Most "light Trucks" will qualify as donors as long as they are from the same or newer model year as your Jeep.  Also, any emissions equipment that was on the donor vehicle engine must also be installed in the vehicle that it is being placed into.  So if you can, make sure you can get all of the smog equipment with the donor, or you will be making several trips to the Junk Yard in search of the necessary parts to complete your project. 

V8, V6, 4 or 6 Cylinder?

Choosing whether to swap in a V8, V6, or just replace your existing 4 or 6 Cylinder engine is a decision you need to make based on what you really want, what level of complexity you are willing to accept, and how much time and money you are willing to put into the project.

Direct replacement of the existing 4 or 6 Cylinder Engine

If all you want to do is get your Jeep back on the road again after your existing engine just blew up, then a direct swap with the same engine will be the easiest, cheapest, and least complicated.

You can find a donor from a private party sale, or look around at Junk Yards for a replacement. Or if it is within your budget, then you could purchase a brand new or rebuilt engine from the manufacturer or through one of many suppliers either on line or through a catalogue or local parts store. The cost of associated with either of of these choices will range from around a few hundred dollars for a private party purchase to around two thousand dollars for a brand new or rebuilt engine. If you can afford it, of course the wisest choice would be to purchase a brand new crate engine from the manufacturer. You will get a warranty and you will know that the engine is going to last several more years. Buying a used engine will cost less, but you take the risk of getting an engine that has suffered unknown levels of abuse. Going through a Junk Yard might get you a "guaranteed to run" warranty, but that's about as far as it will go, so once you have it in the Jeep, you are stuck with it. There are a lot of ways to minimize the risk of getting a bad motor, and the most important thing you should do is to perform a diligent inspection of the engine prior to purchasing it. 

Choosing to go with a the V6

V6 engines in Jeeps are another very popular swap choice. They are generally smaller and lighter, they fit in the engine bay a little easier, and they don't usually require a lot of modification to your cooling system. There are a lot of great V6's out there that will make a great power plant for your Jeep. The  newer Vortec V6's have gobs of power and torque that will propell your Jeep up and down the road with sufficient satisfaction to the driver.

Bottom Line: There are other choices, of course, but as far as I am concerned, if I were going to put a V6 in my Jeep, it would be the Vortec. I will gladly add more options here if anyone wants to argue for them, but for now I would like to leave it alone and move on.

Carbureted or Fuel Injected?

The next question is whether to go with a carbureted or fuel injected set up. There are definite benefits and drawbacks to both, and ultimately the choice is mostly a matter of personal opinion.

The major benefit to carbureted engines is the simplicity of installation. There will be little or no need for changing the electronics in your Jeep to accomodate a carburetor. On the drawback side, you will not experience the reliabillity, performance and fuel economy that can be had with a fuel injected set up.

The benefits of going with a Fuel Injected set up is increased fuel economy, better performance and fairly carefree reliability. Once set up and ready to go, you will probably never have to worry about it ever again. You'll get better throttle response, and you can run these things at any degree of angle without so much as a sputter of the engine (whether you want to or not is another qestion).

The usually over-exagerrated drawback to fuel injection is that it may require some fairly complicated manipulation of the electronics of your Jeep. The wiring harness is different from your Jeep and as such, it will have to be made to work with the Fuel Injected system of the donor vehicle, or you could purchase everything you need for the swap through one of several companies that speciallize in making these changes. If you are so inclined, as well as a bit competent in electrical theory and procedure, then you shouldn't have too much trouble performing the changes yourself.

Bottom Line: A carbureted set up is easier, but the increased performance, fuel economy and reliabillity of fuel injection is well worth the time and effort.

Performance – 4 Wheel Parts