Ultimate Diesel Builder's Guide - - Contents -

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.

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