From the first day we drove our used 2.5L-equipped ’97 Jeep Wrangler home, we longed for more power under the hood. We sprang for the great deal on the used Jeep with the underlying expectation of one day swapping-in a more powerful engine, but as the years rolled on, the factory four-cylinder remained quietly in place. Like so many of you, we loved to complain about how weak the factory four-popper was, but were far too cheap to drop the coin on an ultra-pricy Hemi conversion.
For all of its faults, the 2.5L never really let us down—it is, at its core, a very reliable engine. In the end though, our goals of furthering the build and increasing the Jeep’s on- and off-road capabilities sent us looking for a cost-effective way to gather more ponies behind the grille. With so many engine conversions and opinions across the globe, we opted for what appeared to be the best bang-for-the-buck V-8 swap—the 5.9L Magnum V-8.
Since our donor engine did...
Since our donor engine did not come with a power steering pump, we used this opportunity to upgrade to a hydraulic-assist steering system from PSC Motorsports. And while it is not recommended to run the stock V-8 pump with the factory steering gear box, it can be done by having a set of custom hoses made.
Available in Grand Cherokees, Dodge Rams, Dakotas, and Durangos, the 5.2L 318ci and 5.9L 360ci were two of the most common engines used throughout the ’90s. Now, nearly two decades later, these powerful V-8s can be had for dirt cheap, along with the entire donor vehicles themselves. Though storing a truck carcass can be a real pain, it makes engine conversions much easier, as many of the miscellaneous parts and pieces you’ll need can often be picked from the donor rig.
For our conversion we pillaged a 5.9L and 46RE automatic transmission from a ’99 Dodge Durango. Since our Jeep was already under construction at Off Road Evolution in Fullerton, California, we added on one more item to the list for the expert Jeep crafters to help us out with. Off Road Evolution is a full service 4x4 shop that is experienced with all projects, big and small. In this installment, we’ll show you the initial breakdown and list the essential parts and pieces you’ll need to achieve the conversion. Be sure to check back with us next issue as we put all the pieces in place.
Part Numbers
•Upper radiator hose: E71953 (Auto Zone)
•Lower radiator hose: D71954 (Auto Zone)
•Engine mounts: 713094 (Advance Adapters)
•Radiator: 716685 (Advance Adapters)
• 23-spline input shaft: 716095 (Advance Adapters)
•1-inch Daystar Body Lift: KJ04508BK (Daystar Products)
To achieve a little more elbow...
To achieve a little more elbow room we removed the entire front clip from the TJ. This may seem like a lot of work, but it’s actually pretty easy and will save you a ton of aggravation and time later on.
The scariest part of most...
The scariest part of most engine conversions is the dreaded electronics. We decided to make life easy on ourselves and leave the cutting and splicing to the experts. This required that we send both the donor vehicle’s V-8 harness and factory 2.5L harness along with the fuse block to Hotwire Auto. Be sure to let the company know if you’ll be converting to an automatic transmission from a manual, as this will require an extra fuse and insert. We’ll show more on how Hotwire Auto makes engine electronics a plug-and-play affair in Part Two.
The factory 2.5L and AX-5...
The factory 2.5L and AX-5 powertrain had served us well over the years and was still in working order when we plucked it from the Wrangler. Though we suggest holding on to your stock parts until the V-8 swap is complete, selling our engine and transmission combo helped offset a good portion of our conversion cost.
One part that is not required...
One part that is not required for the V-8 conversion but is strongly recommended is a 1-inch body lift. We installed a 1-inch kit from Daystar so we could tuck the new powertrain as high into the tub as possible. The mild body lift also made more space for routing the exhaust.
Our 5.9L from the ’99 Dodge...
Our 5.9L from the ’99 Dodge Durango came with most everything we needed, with the exception of a few pieces of smog equipment. Be sure to spend as much time as you can rummaging junkyards for any assorted pieces (like smog equipment) that are missing. These items are very pricy at the dealer, and a few minutes in the field digging can save you a lot of change.
To secure the engine in place...
To secure the engine in place we bolted on a set of Advance Adapters Chrysler V-8 engine mounts to the block. On the frame side we cut off the factory mounts and welded on the other portion of the Advance Adapters kit. Be sure to keep the hardware loose, as it will make alignment of the transmission mount and assorted linkage much easier.
The 5.9L cooling inlet and...
The 5.9L cooling inlet and outlet ports are positioned opposite as compared to the factory four-cylinder. To accommodate this change and increase the cooling area, we went with an Advance Adapters Jeep V-8 radiator that’s designed to bolt in place in a TJ.
Though the Advance Adapters...
Though the Advance Adapters unit can be used as equipped, we had our local radiator shop weld on a larger-diameter lower inlet so we could run a factory lower hose from a 5.9L ’99 Dodge Durango. The upper hose came from the same Durango, but it needed to be trimmed down a few inches.
To finish out the cooling...
To finish out the cooling equation we used a fan from a ’98 5.9L Jeep Grand Cherokee and a radiator shroud from a ’99 4.0L Jeep Wrangler. The junkyard is a great spot to pick up both parts, but since both items are relatively low cost, you’ll be OK grabbing them from a dealership if you have to.
Since our 5.9L isn’t running...
Since our 5.9L isn’t running any extreme power adders the factory four-cylinder fuel pump will work just fine to feed the engine. Though dropping the tank is not required for the conversion, it’s not a bad idea to test the output pressure of your old pump and buy a new one if it’s low.
Our Jeep was equipped with...
Our Jeep was equipped with the AX-5 manual mated to an NP231 transfer case with a 21-spline input gear. Moving up to the 46RE Dodge transmission required us to swap out the factory T-case input with a 23-spline unit from Advance Adapters.
One thing we had terrible...
One thing we had terrible luck with was the factory Dodge V-8 computer. After going through a couple of junkyard ECUs (engine control units) and having no luck getting the truck running, we ordered a factory replacement unit from Auto Computer Exchange. The company builds the computers to spec and requires an ECM core. We suggest trying your donor computer at first, but Auto Computer Exchange is a reputable backup plan for when things just won’t compute.