A P-Pumped 7.3L Power Stroke Making 1,800+ HP

A P-Pumped 7.3L’s Climb To The Top

Truck pulling is a profound sport. Even though hundreds of thousands of dollars go into the top-running trucks each season, most of the rigs you see blasting down the track aren’t new. Rather, they’re the same old familiar faces you’ve been watching for years. Under the hood though, it’s a whole different story. Big money is dumped into ﬁnding more horsepower, while countless hours are racked up in R&D and dyno time. So what happens when you take a well-known truck with a proven chassis and grace it with an up-and-coming engine package? You get the story of Joe Wiltse and Rob Thurow, the owners of one of the strongest running P-pumped 7.3Ls we’ve ever come across.

At the heart of the engine (and that 1,800 hp number) dwells an 8-cylinder inline injection pump. Based off the Bosch unit found on DV800 Internationals, Hypermax fits the body with 13mm, 14mm, or 15mm plungers (de- pending on the customer), its own customized cam, and select other internal components. While we weren’t given any flow numbers, we were told the pumps timing is set higher than 35 degrees.

More than seven years in the making, and after Hypermax exhausted every possibility of the HEUI system providing the kind of power needed to win, this P-pumped 7.3L Power Stroke was built to power Joe Wiltse and Rob Thurow’s ’97 F-350. On the dyno, the engine made north of 1,800 hp. On the track, it made 29 trouble-free passes in 2015. In the future, Hypermax plans to take things a step further with a common-rail 7.3L program, where even more power will be on the table for serious competitors.

THE TRUCK

Finding a V8 under the hood of Joe Wiltse’s old-body style Ford wasn’t always the case. In fact, the truck was originally built for the street and was propelled by a 12-valve Cummins. Put together from the frame up, the aforementioned 5.9L was set between the frame rails; an NV4500 was installed, and a Dana 80 from a Dodge was bolted in place out back. But, as is oftentimes the case with sled pullers, Joe’s addiction to the dirt soon got the best of him—and the truck.

After pulling competitively in the now- defunct 2.8 Class, Joe bumped his Cum- mins-powered Blue Oval into the 3.0 Class, where he became his local points champion for ﬁve consecutive seasons. Still, something was missing. While Joe enjoyed every minute of running out front, he didn’t like the reaction fans sometimes gave the truck. “It sucked when people looked under my hood and said: ‘Oh, an- other Cummins…,’” he told us. “So I wanted to do something different.”

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“1,800-PLUS HORSEPOWER”

Being that pre-Super Duty Fords are considerably lighter than newer trucks, Joe has always benefited from being able to hang a lot of weight out front. When you factor in the weight box, weights, ice box, fuel cell, dry sump oil system, and all plumbing, somewhere around 2,000 pounds sits forward of the front axle.

Sporting an SQHD axle out back makes for a virtually indestructible rear end. SCS air- craft quality alloy axle shafts, a full spool from Pro Fab Machine, and 6.20 gears further bulletproof the massive SQHD, as well as give it an ideal axle ratio.

THE ENGINE

Thanks to his close friendship with Max Lagod of Hypermax Engineering, Rob Thurow had the inside track on a killer P- pumped 7.3L engine program that was set to debut in 2011. But due to Max’s unfortu- nate passing in March of that year, Rob was handed the reins and given the job of putting the Hypermax name in the win- ner’s circle. After three seasons of cam- paigning the setup in his own truck (and making steady progress year after year), Rob hooked up with Joe in the summer of 2014. It was the perfect time. He had a track-tested engine, while Joe had a proven truck with the right driveline parts.

Built 100 percent in-house at Hyper- max, the 7.3L utilizes a factory, unﬁlled cast-iron block and a modiﬁed factory crankshaft. Holding the block together, se- curing the crank, and tying the main bear- ing caps to the oil pan rail is a Hypermax bedplate. Hypermax forged connecting rods to modiﬁed Mahle Motorsports pis- tons, while a billet front cover (with provi- sions to incorporate the inline injection pump) and a custom grind billet camshaft round out the bottom end components. Up top, a set of extensively ported factory- based heads feature Hypermax special-ma- chined combustion seals, billet rocker arms, pushrods, and Hi-Rev valve springs. The en- gine also uses a dry sump oil system (with two scavenge stages and one pressure stage) to maintain oil pressure.

“IT SUCKED WHEN PEOPLE LOOKED UNDER MY HOOD AND SAID: ‘OH, ANOTHER CUMMINS…’ SO I WANTED TO DO SOMETHING DIFFERENT.” —JOE WILTSE

The Hypermax 3.0 charger dwelling at the back of the lifter valley is one of the key ingredients in the truck’s success. During a typical pull, it produces be- tween 75 to 80 psi of boost, and routes the compressed air through a Hyper- max air-to-water intercooler. Water injection is sprayed pre-turbo and before reaching the air-to-water unit to keep EGT in the desired 1,600-degree range.

A Pro Fab Machine Reverser transmission with a 3850 triple disc South Bend clutch and a Quick Change transfer case gets power transferred to the axles. This transfer case is the key to making quick (i.e. “quick change”) gear changes at the track, if need be. Although we don’t know what gear Joe and Rob typi- cally run, we do know it allows the truck to storm down the track with as much as 30 mph worth of ground speed.

The ability to run a 158-inch wheelbase in Joe’s local Pro Street Diesel Class (Illini State Pullers) is the reason behind the truck sporting a 10-foot bed. With the help of friends, the frame was cut and length- ened by two feet. The added frame length also provided for use of a longer draw bar.

BIG FUEL AND AIR

Taking up plenty of space in the lifter valley is a Bosch inline injection pump off of a DV800 International. It routes fuel to eight mechanical injectors, positioned under Hypermax cast-aluminum valve covers. The P- pump gets a steady diet of high-pressure diesel from a gear driven lift pump, and a 3.0-inch inducer turbo sits at the back of the lifter valley. Cast and built by Hypermax, the billet 76mm wheel charger sends 75 to 80 psi of boost through an air-to-water in- tercooler, and ultimately the engine.

In all honesty, nothing about the engine is crazy or overly exotic—which is the best part. The heads are factory-based, cast-iron units. The turbo sits in a location remi- niscent of the stock position. A factory water pump is employed (albeit being driven by an 8mm belt). And ﬁnally, an un- ﬁlled, factory block is utilized. However, while the engine may be short on ﬂash or one-off components, it employs a host of parts designed and proven to handle big power. At 1,800-plus horsepower, this en- gine has what it takes to be competitive among the highest 3.0 ranks in the coun- try. While partnerships seem to be a rarity in the somewhat-secretive game of truck pulling, Joe and Rob have made it work ex- tremely well. Since combining resources, they’ve shared a dozen wins and ran neck- and-neck with some of the best-running Haisley and Scheid-built Cummins pullers in the nation. With a Second Place points ﬁnish in their local pulling circuit last year and plenty of upgrades coming by way of Hypermax over the winter, you can bet the Relentless Ford will be in ferocious pursuit of the top spot in 2016. DW

The trend toward Nitto Mud Grapplers in 3.0 Classes that began a few years ago wasn’t lost on Joe and Rob. According to Joe, the aggressive nature of the mud tires load the engine harder than all-terrain tires can (namely BFGoodrich All Terrain T/A’s and Interco TrXus STS’s).

Things definitely have come a long way for the Relentless Ford. This shot, taken in 2009, gives you an idea what the truck looked like back in the day—a 2.8 Class rig with the factory 8-foot bed and a 12-valve Cummins under the hood.

SPECS:

YEAR/MAKE/MODEL: 1997 Ford F350

OWNERS: Joe Wiltse and Rob Thurow

HOMETOWNS: Maple Park, IL and Davis Junction, Illinois

ENGINE: 7.3L Power Stroke with Hypermax Engineer- ing bedplate, forged rods, Mahle Motorsports pistons, Hypermax billet custom grind cam, billet front cover, ported heads with custom-machined wire-ring combustion seals, billet rocker arms, chromoly pushrods, Hi-Rev valve springs, dry sump oil system

FUEL: Hypermax inline 8-cylinder Bosch P-pump, International-based injectors, gear driven lift pump

AIR: Hypermax 3.0-inch inducer turbo, air-to-water intercooler

INJECTABLES: Water injection

TRANSMISSION: Pro Fab Machine Reverser with South Bend 3850 triple disc clutch, Pro Fab Machine Quick Change transfer case

HORSEPOWER: 1,800+ hp (dyno)

TIRES: 15/75R16 Nitto Mud Grappler

WHEELS: 16×10-inch RealWheels

AXLES: Rear SQHD with Pro Fab spool and SCS axle shafts, front Dana 60 with Yukon locker, 35-spline chromoly axle shafts, 6.20 gears front and rear