A Surprisingly Simple, 700+ HP OBS Ford

Budget-minded drag racers have always had a knack for getting the most out of readily available engines with reasonable performance potential. And savvy gearheads have always had ways of building their own components rather than paying someone else to do it. Steven Davis is one such customer. Smart parts hunting, the ability to fabricate and a well-rounded set of wrenching skills have all contributed to his ’95 Ford F-350 churning out six-second, eighth-mile passes. The best part? The original 7.3L Power Stroke still sits between the frame rails.

“The 7.3L ain’t no powerhouse, but it’s hard to beat. There’s no school like old school.” —Steven Davis

A 367,000-mile forged-rod, stock-bottom end 7.3L Power Stroke is the foundation of Steven Davis’ lightning-quick F-350. Its only hard-part upgrades consist of beehive valve springs from Dyno Proven, Smith Brothers Chromoly pushrods and ARP head studs, which were threaded in one at a time. For fuel, a set of 300/200 hybrid injectors from Full Force Diesel sit above each cylinder, while a Honey Badger Sr. high-pressure oil pump from Dyno Proven maintains the oil volume they require. Dyno Proven also handles the PCM tuning, and Steven navigates tunes via an F8 chip from DP-Tuner.

The proven BorgWarner S467.7 FMW turbo feeds the engine and mounts in the lifter valley, thanks to a T4 turbo mount from Irate Diesel Performance. The corresponding intercooler pipes, intake plenums and up-pipes also came from Irate, while the plastic intercooler was sourced from a 6.0L Power Stroke. Absorbing nitrous blasts and seeing 70 to 75psi of boost on each pass, the non-waste-gated turbo has been extremely durable.

Another readily available yet proven component that made its way onto the truck is the Walbro GSL392 lift pump. Steven built his own electric fuel-supply system around the Walbro unit, which incorporates a pre-filter, fuel filter and a Fuelab regulator, set at 67psi. The Walbro pump pulls fuel from a six-gallon, stainless-steel fuel cell that Steven fabricated himself.

With just six gallons of fuel onboard, diesel heats up fast and can rob horsepower. To curb this, Steven routes fuel through a Derale electric auxiliary cooler that he remote-mounted to a cross member in the bed.

A Nitrous Express Lightning 250 system adds another 180hp into the mix. But Steven’s nitrous system goes beyond that, as he engineered and built his own fogger system within the intake plenums, to get as close as possible to individually feeding each cylinder a solid dose of N2O. The fogger system helped the truck gain more than 100hp on the chassis dyno, and Steven says it is calculated and sized to support a 250hp hit.

Bought for just $700, Steven’s initial goal for the truck was to put together an E.T. Bracket Class candidate. What he didn’t plan on was the truck running low eights almost immediately, followed by high sevens within the first year of ownership. You could say it snow-balled from there.

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“We’d make a change, and then go to the track on Friday night,” he told us. “If the truck went faster, we’d leave it alone—and if it went slower, we’d pull it back off.” It rarely went slower….

367,000 Miles

As proof that some 7.3L Power Strokes just won’t die, the 21-year-old, 444ci V-8 under the hood has 367,000 miles on the clock. To date, it has shown no signs of giving up, either. Regularly exposed to 4,000-rpm and 70 pounds of boost, a set of Dyno Proven beehive valve springs are employed to eliminate valve float and valve creep. Chromoly pushrods from Smith Brothers are also utilized, along with a set of ARP head studs that Steven threaded in one at a time.

Fuel, Oil, Tuning

Big-power production called for big injectors, so a set of Stage 3 units from the nearby Full Force Diesel were installed. The hybrid injectors flow 300cc and feature 200-percent nozzles. A Dyno Proven Honey Badger Sr. high-pressure oil pump keeps ample injection-control pressure (ICP) on tap, and Steven built his own fuel supply system—which incorporates a Walbro pump—to keep the fuel side of the HEUI injectors happy. Dyno Proven custom PCM tuning ties everything together, and an eight-position F8 chip from DP-Tuner is used to navigate through the tunes.

Box Turbo and Nitrous

The proven BorgWarner S467.7 turbo is positioned at the rear of the lifter valley thanks to a T4 mounting kit from Irate Diesel Performance. Irate’s intercooler pipes, three-inch intake plenums, and stainless-steel up-pipes are also utilized. Adding even more air into the equation is a two-stage, progressive Nitrous Express system, which is activated immediately after the truck launches. On the dyno, Steven’s nitrous system added an extra 180hp to the truck’s fuel-only numbers.

Front and rear traction bars keep the Dana 60 and 10.25 Sterling stationary during the course of boosted four-wheel drive launches. Both sets were built by Steven to rule out hopping issues up front, and to stop axle-wrap in the rear.

You won’t find any leaf springs in the rear of Steven’s OBS, just a set of QA1 coil-over shocks. For optimum traction, the rear differential was treated to a welder (i.e. Lincoln locker), which Steven likes to refer to as his “Miller locker.” The Dana 60 up front was fitted with a budget-friendly Spartan locker.

Gutted and lightened, the interior is about as no-frills as it gets. Along the dash, Steven keeps an eye on oil pressure, water temp, boost, transmission temp and bottle pressure, for the 10-pound NOS bottle.

Stock E4OD

Believe it or not, Steven believes the E4OD in his F-350 is a stock automatic. It hasn’t skipped a beat since he purchased the truck, hence going untouched up to this point. The one upgrade it has seen is the addition of an unidentified (and free) triple-disc torque converter, and the only repair it’s received is a replacement (stock) input shaft. How does he get away with it? For starters, the truck’s light curb weight of 5,450 pounds makes life much easier on the transmission, and spending most of its time in the eighth-mile as opposed to the quarter-mile makes its time spent in overdrive very brief. Still, the fact that it’s survived more than 70 dyno pulls, and well over 500 drag-strip passes, is impressive to say the least.

“It’s fun watching people lose to an old dinosaur.” —Steven Davis

In an age of over-the-top, big-money builds, Steven’s is a throwback to the grass roots, homegrown days of diesel performance. His setup is so simple it’s surprising. In areas where money had to be spent—such as the injectors and turbo—it was. But in areas where something could be built, installed or improved upon—like the roll cage, traction bars, fuel cell and gutting of the truck—Steven did the work himself. The end result is a reliable, low-buck, lightweight OBS Ford that’s a riot to drive. In the future, Steven plans to up-size to 350/200 injectors, add dual high-pressure oil pumps, spray a little more nitrous, and run the 6.70 Index class (10.50 quarter-miles). With a track record of going faster every time it’s unloaded from the trailer, we don’t see that being a problem. DW

On a big nitrous pass, the 7.3L Power Stroke sees as much as 4,200rpm. A 6,000-rpm Pro-Comp Ultra-Lite series tach from Auto Meter allows Steven to watch engine speed and recall peak rpm after each run.

A B&M shifter graces what we’ll call Steven’s “mystery transmission.” As far as Steven can tell, the E4OD is completely stock, and is the same one that was under the truck when he bought it. So far, it’s survived more than four years’ worth of drag-racing abuse, with a triple-disc torque converter being the only known upgrade.

To keep the truck glued to the track at all times, Steven runs a set of 13.00×16 M&H Racemaster slicks mounted on 16×12-inch Mickey Thompson Classic III wheels. Thanks to the stickies, the truck is a downright animal out of the hole, often cutting 60-foot times as low as 1.48 seconds.

At the 2016 TS Performance Outlaw Drag Race, Steven turned off the nitrous, detuned the fueling and ran the 12.0 Index class. He would end up finishing in second place in a 32-truck field. It takes a lot of talent to slow a truck down by more than a full second and remain competitive. This speaks volumes as to Steven’s driving abilities, and also to how well he knows his truck.

Proof is in the puddin’, as they say: This 6.91-second, eighth-mile pass at 98mph (Steven’s personal best) could’ve easily been a 10.8-second pass at more than 120mph in the quarter. In the future, Steven plans to grace the truck with a fiber-glass hood, spray a little more nitrous, and compete in the 6.70 Index class (10.50 quarter-mile).

Specs

Year/Make/Model: 1995 Ford F-350
Owner: Steven Davis
Hometown: Woodbury, Tenn.
Odometer: 367,000 miles
Engine: 7.3L Power Stroke with ARP head studs; Dyno Proven beehive valve springs; Smith Brothers Chromoly pushrods
Fuel/Oil: Full Force Diesel 300/200 hybrid injectors; Walbro GSL392 lift pump with homemade fuel system; Fuelab regulator; Dyno Proven Honey Badger Sr. high-pressure oil pump
Turbo/Air: BorgWarner S467.7 FMW turbo; Irate Diesel Performance T4 mount; stainless-steel intercooler pipes; stainless-steel up-pipes; aluminum 3-inch intake plenums; plastic 6.0L intercooler
Injectable(s): Nitrous Express two-stage progressive nitrous system
Tuning: Dyno Proven via F8 DP-Tuner chip
Transmission: Stock E4OD with triple-disc torque converter
Horsepower: 861hp (dyno); 700+ hp (track)
Torque: 1,532 lb-ft (dyno)
Tires: 13.00×16 M&H Racemaster drag slicks
Wheels: 16×12 Mickey Thompson Classic III
Suspension/Steering: Leaf spring (front) with traction bars; QA1 coil-over shocks (rear) with tractions bars
Axles: Spartan locker (front); welded differential (rear); 3.55 ring and pinion

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Pinaki Bhattacharya

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