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Kymera: Fab Fours Cummins-Powered 2015 Chevy Colorado

Posted in Features on March 10, 2017
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It’s called Kymera. It’s a name that’s derived from the Greek mythology creature Chimera—you know, the one that was part goat, lion, and snake. Yay, we hadn’t heard of it either, but it makes perfect sense once you realize the different pieces that make up what started off as a ’15 Chevy Colorado.

Fit with a fully built 12-valve Cummins diesel engine, AxleTech 4000 axles, and detailed metalwork more commonly found on high-end hot rods, this Bow Tie is beyond unique. Debuting at the 2016 Specialty Equipment Market Association (SEMA) Show in Las Vegas, Kymera was the brainchild of Fab Fours CEO Greg Higgs. Teaming up with Tim Odell at Vice Unlimited, the American bumper manufacturer wanted to build something so over-the-top that everyone would stop and take notice.

Powering the truck is a 5.9L Cummins diesel that was sourced from BD Diesel Performance. The 12-valve engine had extensive work done to punch out the estimated 650 hp and 1,200 lb-ft of torque. A BD injection pump sends fuel through 8mm BD injection lines to BD high-flow injectors. An ATI harmonic balancer was also used in conjunction with a Keating Machine tappet and timing cover. Topping things off are BD valve covers.

As good as it looks, we were curious how the pickup would perform on the trail. Luckily, we got the chance to tag along on Kymera’s first outing at the Flats Offroad Park in Marion, North Carolina. From full-throttle hill assaults to twisting the suspension on the muddy trails, we got to see firsthand how this presumed showpiece works in the dirt. While there are still a few kinks to work out, the rig proved that it can impress on-road and off.

With plenty of fuel on tap, there needed to be an appropriate air mixture. This air density boost came by way of BD’s 6BTA twin-turbo system. The low-pressure turbo is fit with a 66mm compressor wheel and 80mm turbine wheel. The high-pressure turbo was built with a 58mm compressor wheel and 65mm turbine wheel. This setup helps achieve power faster versus a single turbo and allows the truck to be more versatile in different off-road arenas.

At A Glance

Vehicle: ’15 Chevy Colorado
Owner: Fab Fours
Stomping grounds: Lancaster, South Carolina
Build Time: 10 months
Engine: 5.9L BD Diesel twin-turbo Cummins
Transmission: 47RH
Transfer case: Advance Adapters Atlas 2
Low range ratio: 3.8:1
Crawl ratio: 52.60:1
Front axle/differential: AxleTech 4000/stock pneumatic locker, 5.65 gears
Rear axle/differential: AxleTech 4000/stock pneumatic locker, 5.65 gears
Front: Double-triangulated four-link w/18-in-travel Fox 3.0 Factory Series coilovers and 4.4 Factory Series Bypass Piggyback shocks, Fox 2.0 Factory Series bumpstops, Currie Antirock sway bar
Rear: Double-triangulated four-link w/18-in-travel Fox 3.0 Factory Series coilovers and 4.4 Factory Series Bypass Piggyback shocks, Fox 2.0 Factory Series bumpstops, Currie Antirock sway bar
Steering (f/r): Full hydraulic w/double-ended steering rams
Tires: 405/70R20 Alliance Multiuse 550
Wheels: Custom 20-in
Armor: Custom 2x4-in, 0.250-in boxed square and 1 3/4-in, 0.120-wall tubing chassis
Cool stuff: Be Cool radiator, Rough Country LED fog lights, GenRight taillights, Katzkin leather, Dakota Digital instrument cluster, Warn winch

The custom saw-blade roof ties into the custom interior cage, which is comprised primarily of 1 3/4-inch, 0.120-wall DOM tubing. Hiding the BD-built 47RH transmission is a custom sheetmetal dog box. This beautifully crafted setup has a hand-built center console that still makes enough room for the Katzkin draped leather Colorado seats. To help keep an eye on the vitals, a Dakota Digital instrument cluster was modified to fit in the Colorado’s stock dash.
Since the engine now resides in the bed, the space under the hood was utilized for the 15-gallon fuel cell, Odyssey dry cell battery, and Be Cool custom radiator. Along with the nicely done coilover tower that peeks through the hood, special considerations had to be made for the truck’s most basic function- brakes. Since there wasn’t enough room for the brake master cylinder to mount forward, a cantilever arm was fabricated, which allowed the brake system to be mounted horizontally along the firewall.
For as long as we can remember, the 2 1/2-ton Rockwell axle has been the go-to for those looking for ridiculously strong take-out military axles. That’s no longer the case. These days, AxleTech 4000 axles are the go-to. Originally found under the U.S. military MRAP, these axles are rated up to 19,800 pounds and have massive planetary gear hubs. This particular set is fit with a final gear ratio of 5.65:1 and paired with AxleTech’s pneumatic differential lockers.
Out back, a matching steering AxleTech 4000 axle is secured by a double-triangulated four-link suspension. As is the case with the front, a double-ended hydraulic steering ram is used to increase the maneuverability of the 130-inch wheelbase truck.
Tucked under the high-clearance composite bellypan is gear-driven Advance Adapters Atlas 2 transfer case. Given the amount of travel the rig has and unconventional drivetrain layout, the truck is currently pretty hard on driveshafts. Currently, Fab Fours is examining a few possible solutions that would help the situation.
More commonly used on go-fast trophy trucks, the shock setup on Kymera is colossal. Fit at each corner of the rig is a Fox 3.0 Factory Series coilover and 4.4 Factory Series bypass shock. These 18-inch-travel shocks make for some incredible wheel travel. To make sure the shocks don’t get damaged after a jump or big hit, Fox 2.0 Factory Series bumpstops were added all around.
One of the most visually impactful modifications done to the truck was the 4-inch roof chop. Vice Unlimited Tim Odell’s background in bodywork really came through with how smoothly this modification was executed. Special care was also taken to ensure Kymera retained the look of the Colorado. This meant fabricating custom fenders, panels, and bedsides.
SEMA trucks often get the stigma of being nothing more than show pieces. Thankfully, Fab Fours likes to play in the dirt. While CEO Greg Higgs states a more versatile set of 40-inch Nitto Mud Grapplers will be replacing the 42-inch Alliance tires soon, the truck is extremely impressive as it sits. The company plans to haul this truck all over the U.S. to different wheeling events. So, hopefully you too can get a chance to see this 7,000-pound machine do work on the trail.
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