Watson Family Super Stock pull truck
Of course we all agree that sled pulling is a fun motor sport where diesel truck enthusiasts can gather and enjoy watching and/or competing with fellow gearheads. It's common to see families at the pulls on both sides of the fence as spectators and as competitors. The Watson family from Batavia, Ohio—paul and Deborah and their two sons Chris and Randy— have enjoyed sled pulling for years and decided to get serious about running in the fiercely competitive Super Stock Diesel Truck class with a machine of their own making. To run with the big boys at the top level of diesel truck sled pulling is no easy task, but the boys have worked together in their family construction business as well as building and wrenching on various diesel trucks for the better part of their lives, so they thought they would be able to build the new truck as well.
Rather than buying a chassis and dropping a built Cummins engine in it then hanging a fiberglass body on it and calling it their own, the Watsons wanted to build the truck themselves from the ground up as a family project with help from a few friends. Not only did they want to build the truck themselves, they also wanted to do it their own way, with a Duramax-based engine, rather than the tried-and-true Cum- mins-based engines that are used by the vast majority in the class.
Starting with a stack of DOM steel tubing and working in their home shop, the Watsons went to work designing the truss-work chassis with a 158-inch wheelbase and plans for a large suspended GMC front axle assembly and massive Rockwell rear axle integrated into the chassis. Once the design was completed they went to work cutting, bending and notching tubing, then fired up the welder and connected the pieces together as the chassis came into shape. To meet the 7,500 weight limit and keep as much weight out front as possible, the Watsons built a weight box for the front of the truck. But rather than going with a simple steel box they had a local shop waterjet Chevrolet Bowties out of 3/4inch steel plate, then bent the front piece at the
center 8-degrees to match the factory Bowtie angle and create the unique weight box, which weighs about 800 pounds on its own.
Of course, the rear of the truck has the axle housing solidly welded into the chassis. The Rockwell is stuffed with SCS internals to put the power to the ground. Up front, the suspension they designed uses three parallel DOM link bars with QA1 heim joints to mount them at the chassis and front axle, which also uses SCS internals. A pair of QA1 adjustable coilover shocks are used on each side along with Hypercoil springs to keep the front axle planted on the ground no matter how rough the track gets. Braking comes from 10-inch Wilwood rotors clamped by Wilwood calipers that are independently actuated with their own pedal on either side of the steering column. Steering is handled by a PSC hydraulic ram that actuates custom spindles through a set of fabricated links with QA1 heim joints.
The chassis is topped with a 2013 Chevrolet extra-cab fiberglass body from GTS Fiberglass in Troy, Michigan. The Watsons fabricated an internal skeleton to hold the body pieces together in proper alignment while it is tilted back with a pair of polished stainless steel hydraulic rams. After the custom-fabricated chassis and the body’s skeleton were completed, they painted everything Dodge Viper Red to really pop when the body is lifted. The inside of the body and some of the trim panels were treated to a glossblack paint finish, while the exterior of the body received several coats of GM Ghost White paint
to create a solid foundation for graphics. Shelby Krebs at Cincinnati Graphics and Design created the design, then Mike Hacker at Pro Trac Solutions printed and installed the wrap on the fiberglass body. Hacker also installed the Bowtie graphic to complete the weight box.
Since the Supermax was built specifically for sled pulling, the interior is built just for that purpose with a no-frills approach. But the Watsons didn’t forget to pay close attention to the details in the interior, either. They installed a Kirkey aluminum racing seat as well as G-force Racing Gear 5-point harnesses to keep Randy Watson in the seat as he pilots the truck down the track. He steers the truck with a lightweight Joes aluminum racing steering wheel on a quick-release hub and fabricated steering column. To data log each run and give Watson a quick visual while he blasts down the track, they installed a Racepak IQ3 dash monitor system along with a pair of LED warning indicators for low oil pressure and max EGT limit to help the driver easily monitor the engine during each hook.
When the body is lifted high into the air the glory of the Supermax truck is revealed with the highly detailed and well-built, one-off Duramax engine. It all starts with an LML GM block that was bored 0.010 over and fitted with a Crower billet crankshaft swinging a set of Crower rods and Arias pistons through the bores. A Socal Diesel billet camshaft controls valve actuation in the Wagler Competition Products billet ductile iron Port Max heads, which have 0.750 inch taller ports than stock GM heads for increased airflow and volume. The cylinder heads are capped off with a set of custom-fabricated Super Max valve covers that the Watsons installed on the engine after they completed the build and assembly to give it another custom touch.
Rather than retain the common-rail fuel system on the Duramax the Watsons decided to go with a mechanical system, starting with a Columbus Diesel Supply 16mm Sigma pump to deliver tons of fuel to a set of CDS Billet KDEL injectors through custom-bent stainless steel lines. The pump is driven by a timing gear that the
Watsons fabricated specifically for their one-off application. Fuel is fed from the highly polished stainless steel fuel tank, mounted high and to the rear of the Bowtie weight box, by a Waterman transfer pump.
Spent exhaust gasses are pushed out of the Wagler heads into a set of log-style headers that the Watsons fabricated to flow well and handle the extremely high EGTS that the truck will see as it blasts down the pull track. From there, the exhaust is sent into a Y-pipe before driving the turbine of the first Chaos Fabrication Holset turbo mounted directly in front of the engine. Hot exhaust gasses next flow into another pair of Chaos Fab Holset turbos mounted low on the driver’s side of the chassis. Then the gasses are sent through more piping back toward the other side of the truck, where they turn skyward and are released through a pair of polished stainless steel stacks.
On the intake side, air is drawn in through a large K&N carbon-fiber air filter to protect the turbos and engine from dirt and debris that could be ingested by the low-mounted atmospheric turbos mounted near the left front wheel. After the initial compression stage in the pair of Chaos Fab turbos, the intake charge is handed off to be further compressed by the third Holset turbo. Then the high-pressure charge is routed into a water-to-air intercooler that the Watsons fabricated using a Bell core. Airflow is then routed into the engine through custom-fabricated, runner-style intake manifolds that feed into each cylinder head. The Watsons estimate that their Sigma-injected Duramax engine is currently making around 2,800 horsepower.
To improve the longevity of the Duramax engine, the Watson team ditched the factory wet sump oiling system in favor of a dry sump system. An Aviaid pump handles the oiling chores for the engine as well as a separate oil circuit for the turbos. For the engine, oil is supplied to
the system from a five-gallon tank mounted behind the right side of the weight box, while it is drawn away from the engine using three scavenge inputs from the pump. The Chaos Fabrication turbos have their own oil circuit on the Aviaid pump apart from the engine oil, with a two-gallon oil tank dedicated to keeping all three turbos well lubricated.
The Supermax engine is linked to the SCS reverser through a custom clutch setup made by Kenny’s Pulling Parts in Waynesburg, Kentucky. It uses a custom flywheel and clutch discs with a Molinari Racing Products pressure plate. The assembly is housed inside a Browell bell housing. Power is then channeled to an SCS Reverser and transfer case to send the power to the front and rear axle assemblies through the SCS differentials and axles. To put the power to the ground, the Watsons use a set of 34x18.0-15 Dick Cepek Giant Puller cut tires wrapped around 15 x 18inch Real Wheels lightweight polished wheels up front and Pitbull 34x18.0-15 tires mounted on 15x22-inch Real Wheels lightweight polished wheels in the rear. Bead screws are used on the inside and outside lips of the wheels to prevent them from spinning inside the tires as Randy Watson puts the power down while clawing his way down the track.
The Watson family continues to work on and refine the Supermax truck between their busy daily routine with the family construction business. Their attention to detail, amazing craftsmanship and out-of-the-box thinking has come together to create one of the best-looking pull trucks we’ve seen. It’s yet to be seen if the Sigma-pumped Duramax can keep up with the Cummins-powered rigs that normally dominate the standings, but if anyone can make it work the Watson boys will be the ones to do it! We expect that once they get the Supermax dialed in they will be vying for podium spots and wins on a regular basis. Whether you are a Power Stroke, Cummins or Duramax guy, it would be hard not to appreciate the hard work this family put into their truck and cheer them on, we do! UDBG
TOP LEFT: They did a good job on the door panel and acrylic window, making the fiberglass door look just like a steel original. TOP RIGHT: Up front, the Watsons rely on a set of 34x18.0-15 Dick Cepek Giant Puller cut tires wrapped around 15x18-inch...
The Watsons painted the GTS Fiberglass body GM Ghost White, then Mike Hacker at Pro Trac Solutions printed and installed the amazing graphics, designed by Shelby Krebs at Cincinnati Graphics and Design, to give the Supermax truck a unique look.
To Watson’s right you’ll see the control levers as well as the intercooler and ice/water tank used to keep the intake temps in check.
With the body down, the sheet metal interior trim helps to protect the driver and finishes off the truck very well at the same time.
With the body lifted, you can see the custom chassis the Watsons fabricated and painted in Dodge Viper Red along with the Kirkey race seat Randy Watson calls home for 300-feet at a time.
The Watsons fabricated the massive “Bowtie” weight box to look great while showing their Chevrolet pride and giving them ample room for weights up front. It is constructed from 3/4-inch plate steel and weighs around 800 pounds empty, and also features...
Looking at the top of the engine you’ll notice the biggest difference from a normal Duramax. This one is sporting a Columbus Diesel Supply 16mm mechanical Sigma pump in place of multiple CP3 high pressure pumps seen on most high-power common-rail...
Looking at the engine from the rear you can see the intake tract from the compound turbo outlet through the Watson family fabricated intercooler and into the fabricated intake manifolds.
Exhaust is routed from the fabricated headers into a Y-pipe before it is handed off to the first turbo. Then it’s passed along to the other two and routed from their outlets up to the passenger side of the truck, where it’s directed up and out of the...
This huge K&N carbon-fiber air filter is employed to keep flying dirt and dust out of the pair of low-mounted atmospheric Chaos Fab Holset turbos while the truck is churning through the dirt.
Looking below the filter, you can see the turbos nestled in between the weight box and front axle. If you look closely you can also see the water injection nozzles as well as the positive air shut-off valves.
Two polished hydraulic rams are used to lift the body to show off the Duramax engine and amazing chassis and detail work that went into the SuperMax pulling truck.
BELOW: The Supermax truck proudly wears a “Bowtie” to the party whenever it comes to a pull. The truck is an amazing build by any standard—but when you consider that it was built as a family project in the Watson’s shop your appreciation for the...
Here you can see more of the Watsons’ fine fabrication skills on display with the DOM steel chassis and massive fabricated axle housing for the Rockwell rear end with an SCS differential.
Looking at the truck from behind, the massive Pitbull tires and huge Rockwell rear axle grab most of your attention, but the custom-fabricated chassis and hitch are equally pleasing to the eye—especially since they are draped in Viper Red paint.
Here’s a birds-eye view of Randy Watson as he pilots the Supermax down the Elnora, Indiana, track.
Sled pulling is a great family sport and the Watson family keeps Grandma Watson in mind every time they bring the truck out.