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6.1 Hemi JK Wranglers - A Pair Of Sixes

Posted in Features on June 15, 2007
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The Jeep JK Wrangler has taken the off-road-vehicle market by storm. Both the Wrangler (two-door) and Wrangler Unlimited (four-door) have been selling so well, Jeep can't keep up with the orders! We wanted to build a JK to take advantage of the new design and to use off-road. It was hard to decide whether to build a two-door Wrangler, which looks great in our opinion, or a four-door Wrangler Unlimited that, when we first saw one, looked to us like a Vegas limo company had added a pair of doors to the Jeep. It grew on us and now we really like the Unlimited, and apprently so do you, since 70 percent of all Wrangler orders are for the four-door.

We called Doc Murdoch at Dave Smith Motors, the largest Dodge Chrysler Jeep dealership in the world, and got a great price on an '07 Wrangler Unlimited Rubicon. Since the Wrangler is selling so well, Jeep was giving no deals to friends, family, or employees of DaimlerChrysler, so the great deal Doc gave us was even sweeter. We drove up to Kellogg, Idaho, where Dave Smith Motors takes up at least half the town, and picked up our new Rubicon.

Meanwhile, in Burnsville, Minnesota, Dan McKeag, owner of Burnsville Off Road, and the Burnsville crew, were busy making engine swaps work in the new JK. Whether it was a 2.8 diesel out of the Liberty, a 5.7 Hemi, or the very nice SRT 6.1 Hemi, Burnsville Off Road was putting them in the new JK Wrangler.

Dan told us that the Controller Area Network bus (CANbus) system used in the JK actually makes some aspects of the swaps easier, as the engine and vehicle communicate with each other. Tony Squire at Squire Incorporated in Mena, Arkansas, supplies his beautiful harnesses for the Burnsville JK swaps. Tony's harnesses look OE and use all factory connectors. Dan is able to flash the JK computers so everything works, including ABS, TCS, BAS, ERM, and ESP, the alphabet soup that makes up the Electronic Stability Program in the JK. The speedometer, cruise, air conditioning, and all other systems work just as they did when the JK rolled off the Jeep assembly line. All future engine swaps in new vehicles are going to have to deal with these systems. Burnsville Off Road has already done it.

We told Dan we still weren't excited about the Unlimited's four doors and he told us that was OK, as he was building a two-door Wrangler Rubicon and would trade us if we still didn't like the four-door at the end of the project. He also talked us into going with the 6.1 Hemi in ours, the same engine he was installing in his silver two-door. This was a hard sell, as the 425hp 6.1 is substantially more expensive than the 5.7 Hemi, being that it's hand-built in Chrysler's SRT plant and balanced, blueprinted, and installed in only the SRT8 Grand Cherokee in the Jeep line. There aren't very many of them out there. At one point, SRT was going to release 24 crate 6.1s and, if our information is correct, about half shipped to dealers before they decided to pull the plug and quit shipping them so the 6.1 would stay exclusive. Dan has searched the country and found most of these crate engines, buying them whenever he can. We decided to empty our pocketbook (JEEP = Just Empty Every Pocket) and go with the 6.1.

The 6.1 in the Grand Cherokee comes with a full-time, all-wheel-drive transfer case with its own bolt pattern, so this wouldn't do. We procured a 5-45RFE five-speed overdrive automatic used in other Hemi applications such as the Dodge Power Wagon. This computer-controlled transmission has proven itself for a number of years and will hold up to the use (abuse?) we plan on dishing out. The stock Rubicon Rock-Trac 4:1 transfer case we used bolts right up to this tranny, as will an Atlas or other T-cases you might want to use. Dan used the same transmission and transfer case in his two-door.

To install the engines in both Wranglers, Burnsville used its JK engine installation kit, which comes with everything needed to install the engine in the Wrangler. This includes the motor mounts, computer flashed for the engine/tranny/vehicle application, wiring harness, Howe Racing aluminum radiator, and all belts and hoses. The Burnsville kit makes it easy not only for the company to do a motor swap into Wranglers, but also makes it easy for a shop or do-it-yourself mechanic to perform the same swap.

The 6.1 shoehorns nicely into the engine bay of the JK using the SRT8 Grand Cherokee front dress. Burnsville keeps the factory cooling fan and shroud and mounts them on the big Howe radiator. We can report this keeps the big mill running cool, even crawling around in the desert when daytime temperatures reach triple-digit levels. Burnsville builds its own mandrel-bent, stainless exhaust system using stainless MagnaFlow mufflers.

Both Rubicons came with the new, excellent Dana 44 front and rearends with electronic locking differentials. These are much beefier than earlier 44s and have 32-spline axles in the rear and 32-spline outers up front. The ring gears are stronger, and the pinions are much larger and stronger. To return the gearing to just about stock with the 37-inch tires both Jeeps would be running, Burnsville installed 4.88 gears from Superior. J.E. Reel supplied the front and rear driveshafts for both Jeeps. The strong CV shafts run true with no vibration problems.

Burnsville installed Full-Traction's 4-inch Unlimited suspension on the two-door Rubicon. The Full-Traction system includes 4-inch coils, adjustable upper and lower control arms for both the front and back, and adjustable track bars front and rear. Bilstein reservoir shocks were installed to handle damping chores. When Burnsville was building our four-door, it was hard to get suspension components as everyone was out of stock, so we mixed things up a bit. Our Unlimited has 4-inch Superlift coils, Superlift front and rear adjustable track bars, Superlift diff guards, Daystar adjustable control arms, and adjustable Walker Evans 2.0 reservoir shock absorbers. The 12-way compression-damping adjustments on the Walker shocks allow us to quickly dial in the suspension no matter what we're doing. A JKS shock conversion kit allowed the Walker shocks to bolt into the JK.

PhotosView Slideshow

LoD makes great-looking bumpers for the JK Wrangler, so LoD bumpers were bolted on the Wrangler. The front LoD is clean and simple and allows the use of the factory foglights. A Ramsey 9500UT winch fit perfectly. Burnsville fabricated a hoop to bolt onto the LoD bumper. The LoD tire-carrier rear bumper easily handled the heavy, 37-inch Nitto/Mopar-Hutchinson beadlock combination. The rear bumper has a nifty toolbox where we like to carry straps and other extraction accessories. Although we didn't get them for this project, LoD also offers gas-can, gear-rack, and Hi-Lift jack carriers for its swing-away tire carrier. Front and rear bumpers from MORE were used on the Unlimited. A Warn 9.5xp was installed here, as well as two HID driving and two HID cornering Soltek Fuego lights from Baja Designs. The lights throw off an unbelievable amount of illumination for off-road night forays. The MORE rear bumper has a swing-away tire carrier that can also carry a Hi-Lift jack.

Inside, Dan decided these two Jeeps needed to stand out a bit more, so he had both of the seats covered in quality charcoal leather. The seats are all leather, even the sides and backs, not matching vinyl like some. He also had the SRT8 emblem embroidered in the seatbacks. The Unlimited also received a Tuffy Security console insert that was covered in matching leather. A Cobra CB keeps us in touch with others. The UltraMount CB antenna mount from Cool Tech is really... well, cool. It mounts inside the license-plate bracket, grounding to the body and using an existing hole in the body to route the antenna cable. Our SWR was no more than 1.5 on all channels, 1 through 40.

Mopar Accessories supplied a number of products, including seat covers that were used until the leather was decided on, a Freedom Top panel bag that keeps the top panels protected when removed for storage, doorsill guards, and a hardtop caddy that holds the hardtop and doors in a handy roll-around cart when they're removed for the summer. Mopar Rock Rail rocker-panel protection and taillight guards were bolted on the two-door. We also plan on installing our Jeep Trail Guide GPS when time permits.

PhotosView Slideshow

OMF beadlocked the factory Rubicon wheels, making them 8 inches wide instead of the stock 7.5 inches. Sticky 37x12.50R17LT Interco TrXus tires were mounted on these wheels. 37x13.50R17LT E Nitto Mud Grapplers were installed on Mopar-Hutchinson beadlock wheels. These wheels beadlock the inner and outer beads and are super high-quality. Spidertrax wheel spacers were used on both Jeeps to get the backspacing to 4.5 inches, where it needs to be with the 37s. The stock steering gearbox and pump work fine on a stock JK. As soon as you modify it with larger tires, a heavy bumper, a winch, etc., an upgrade is in order. Tom at PSC is working on a Delphi steering box, pump upgrade, and cylinder assist for the JK to replace the stock system. Watch for an upcoming article.

After all the work was done, the Burnsville crew delivered the Wranglers to Moab. As all project vehicles we've ever built (or had built) were bug-infested, we were worried about doing the shakedown cruise in these vehicles in front of everyone on trail rides. Our fears were unfounded, though, as everything worked in both vehicles with NO BUGS at all. Remarkable. This is a testament to Burnsville Off Road's attention to detail. Both Wranglers drove superbly on- and off-road. The 6.1 Hemi supplied the most power we've ever had in a Jeep, but it was very tractable off-road where the computer "detunes" the throttle sensitivity in Low range so things don't get jerky in the rocks. The Wrangler was able to snake through the same places all Jeeps have historically been able to get, while the Wrangler Unlimited was phenomenal on steep climbs, going places no one thought possible in the past. Winding through tight rocks and trees was a bit more interesting in the Unlimited though.

So, did we trade? Not yet. We like both vehicles so well that it would have been sixes (pun intended) to trade. The Unlimited offers great room, outstanding climbing ability, and unbelievable popularity in the marketplace, while the two-door has traditional Jeep nimbleness with more comfort than ever available before. The 6.1 Hemi swap makes already great vehicles phenomenal. We REALLY like them. Both.

PhotosView Slideshow
PhotosView Slideshow


Superlift Suspension Systems
West Monroe, LA 71292
Superior Axle & Gear
Rancho Cucamonga, CA 91730
Poway, CA 92064
JKS Manufacturing
Alliance, NE 69301
Walker Evans Racing
Riverside, CA 92516
Ramsey Winch
Tulsa, OH 74116
Full-Traction Suspension
Bakersfield , CA 93313
Interco Tire
Rayne, LA 70578
PSC Motorsports
Azle, TX 76020
Spidertrax Off-Road
Longmont, CO 80503
Warn Industries
Clackamas, OR 97015
Cool Tech
Newhall, CA
Howe Racing Enterprises
Beaverton, MI
(989) 435-7080
J.E. Reel Drive Line Specialists
OMF Performance Products
Burnsville Off Road
Daystar Products International
LoD Genuine Off Road Equipment
Tuffy Products
Cortez, CO 81321
Mountain Off-Road Enterprises (MORE)
Dave Smith Motors
Squier Inc.
Mena, AR 71953

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