A Lightweight, 700HP 7.3L…

…Every Common-Rail’s Worst Nightmare

Pushing the limits of a stock engine is what diesel performance is all about. Unfortunately, some of us find out sooner rather than later exactly how much abuse a factory rotating assembly can handle. With a set of big hybrid injectors and an S369 SX-E bearing down on it, the 190,000-mile, stock, bottom-end 7.3L Power Stroke in David Keyser’s ’97 F-250 decided it’d had enough just eight minutes after being started. But instead of throwing in the towel, David decided to pull the engine, overbuild it, and enjoy his horsepower upgrades reliably.

-Advertisement-
-Advertisement-

Long-Haul, Big HP 7.3L

To ready the 7.3L for maximum longevity, the block was sent to the machine shop side of the local Ford dealer, where it was prepped to accept a main cap girdle and valve-relieved, standard bore pistons, both of which came from Irate Diesel Performance. The rest of the rotating assembly would consist of the factory-based crankshaft and Manley Performance’s forged-steel rods. With the block at Ford, the heads took a trip to Crutchfield Machine for light port work and a performance valve job. Complementing the added airflow of the heads is a Stage 2, billet drop-in camshaft from Colt Cams, while ARP studs make blown head gaskets a non-issue.

DW-1912-FDWHITE-02

After playing with the fire that is a 650 hp stock bottom end 7.3L, David Keyser decided this would be the last time he needed to rebuild his Power Stroke. With Irate Diesel Performance’s main cap girdle and ARP main studs, Manley Performance’s forged-steel I-beam rods, fly-cut pistons, welded piston oil jets, and a welded cam gear, he’s probably right. Other noteworthy upgrades entail a Stage 2 Colt cam, mildly ported cylinder heads from Crutchfield Machine, Power Stroke Products’ 165-ppi valve springs, cryo’d rockers, Smith Brothers pushrods, and ARP head studs holding down the fort.

DW-1912-FDWHITE-03

Taking advantage of the added airflow through the ported heads is a BorgWarner S472 SX-E. Thanks to Irate Diesel’s T4 mounting system, the big single was seamlessly bolted to the back of the lifter valley and makes use of 304 stainless steel up-pipes, 3-inch stainless intercooler piping, and aluminum intake plenums with 3-inch diameter inlets. The charger itself sports a 10-blade 72 mm inducer compressor, an 87 mm exducer turbine, a 1.0 A/R exhaust housing, and builds 55 psi worth of boost.

DW-1912-FDWHITE-04

One look at the top of David’s 7.3L and you’ll notice the factory fuel bowl is gone and that two high-pressure oil pumps are stacked at the front of the lifter valley. With a set of Full Force Diesel 350cc hybrid injectors with 200-percent over nozzles to feed, a Swamps Gen3 HPOP was bolted over the factory 15-degree unit.

Oil and Fuel Supply

After pulling the 275cc injectors that contributed to the bent factory rod, David shipped them to Full Force Diesel to be converted into 350cc units. Equipped with 200-percent over nozzles, the 350/200 hybrids are capable of supporting more than 700 rwhp with the right air and tuning. The big HEUI sticks receive their high-pressure oil supply from a Swamps Gen3 mounted over the factory 15-degree HPOP, and ICP stays in check even with aggressive, dyno-proven tunes from Jelibuilt Performance in the mix. On the fuel supply side, an Irate Diesel electric system designed specifically for the OBS allows David to keep using both factory fuel tanks. The Irate kit entails a Walbro pump, Baldwin filters, and a regulated return system.

Big Air

Packing the cylinders full of air is an off-the-shelf S472 SX-E from BorgWarner. The 72 mm forged milled wheel charger features an 87 mm turbine wheel, a 1.0 A/R exhaust housing, and produces as much as 55 psi of boost. Made to work using one of Irate Diesel’s T4 turbo mounting systems, it sits on a T4 pedestal at the back of the valley, with stainless steel up-pipes feeding the turbine and 3-inch intercooler pipes routing boost to and from the intercooler. A pair of 3-inch inlet intake plenums (also from Irate) introduce plenty of air volume into the massaged heads.

DW-1912-FDWHITE-05

To keep the big hybrid injectors happy, David installed Irate Diesel’s OBS electric fuel system, which came complete with a Walbro GSL392 pump, Baldwin filters, 3/8-inch Parker supply hose, and a regulated return system. Use of the Irate fuel system also means David is still able to utilize both factory tanks and the OEM selector valve. But even though the selector valve can be a bit restrictive, David tells us fuel pressure never dips below 65 psi.

DW-1912-FDWHITE-06

With his hands inside quite a few Allison transmissions, David had no concerns about piecing together his own E4OD. The four-speed auto sports a 300M input shaft, Alto clutches, a TransGo shift kit inside a Twisted Diesel valve body, all steel planetaries, and a triple disc converter from RevMax, which he plans to have re-stalled slightly higher. A billet intermediate shaft, billet forward hub, and several other upgrades are already on the shelf waiting to be installed when his converter goes in for the re-stall.

DW-1912-FDWHITE-07

Insuring the investment in his built E4OD, David installed an auxiliary transmission cooler from Derale Performance. The cooler’s electric fan kicks on when ATF temp reaches 185 degrees and cools things down to 165 degrees before kicking off. However, thanks to the great job the flow-through Derale transmission pan does, David reports it rarely ever kicks on.

DW-1912-FDWHITE-13

DIY E4OD

With Allison rebuilds being a part of his regular duties at work, David was anything but intimidated by beefing up the E4OD in his F-250. He got started by installing all steel planetaries, added a billet input shaft, and then stacked Alto clutches. The valvebody was set up by the folks at Twisted Diesel, and a flow-through transmission pan from Derale Performance was added for improved cooling. Currently, a 1,700-rpm stall triple disc converter from RevMax handles power transfer, but David plans to have the stall speed bumped up to 2,100 rpm in the future. The looser converter should help bring the S472 to life a little quicker.

11-Second Potential

Being that David’s OBS is two-wheel drive, traction can be hard to come by on street tires, and he tells us that even with a soft launch, the truck “wrinkles the tires at the 60-foot mark.” To date, he’s yet to get a clean pass at the track, but the truck has laid down just under 700 hp on the dyno. Once he’s able to get the lightweight Ford to hook, high 11s should be the norm. In the meantime, David is always down for a roll race, where his OBS is capable of hurting a lot of feelings. Trust us, it doesn’t take long for other would-be racers to realize his truck is packing more than pretty wheels, a 4-inch exhaust, and a chip…

DW-1912-FDWHITE-09

Originally equipped with 4.10s, David swapped in a 3.55:1 ring and pinion from Yukon Gear and Axle for lower cruising rpm on the highway. As a bonus, the 3.55s help load the engine harder, which better lights the big S472. To make sure both rear tires are always contributing to the truck’s forward momentum, David also installed a Grizzly locker.

DW-1912-FDWHITE-14

If the potent 7.3L under the hood doesn’t get your attention, this will surely do the trick. When David’s not on the throttle, an old triple-trumpet HornBlasters train horn system, tucked under the passenger side of the bed, helps keeps things interesting.

DW-1912-FDWHITE-08

Keeping the rear 10.25-inch Sterling stationary under power, David installed a set of traction bars off of a friend’s Duramax. The bars make use of beefy heim joints and David reworked the brackets so they could be bolted to both the frame and axle instead of welded.

DW-1912-FDWHITE-10

For a quiet, comfortable ride—along with their ability to maintain traction—David runs Nitto NT420S tread at each corner. In the looks department, a set of 20×12-inch American Force Blade SS8 wheels help liven up the OBS Ford’s old-school body lines.

DW-1912-FDWHITE-12

On the chassis dyno, David’s combination of parts and tuning produced 687 hp at the wheels, along with just under 1,300 lb-ft of torque. When treated to a ghetto fogging of nitrous, his 7.3L responded with 947 hp and 1,630 lb-ft.

DW-1912-FDWHITE-11

The task of making the truck drivable on the street yet maximizing its power potential at the track was left in the hands of Jelibuilt Performance. David’s custom PCM tunes are available on the fly thanks to a Hydra Chip from Power Hungry Performance, which is conveniently mounted next to his transmission temp gauge along the A-pillar. So far at the drag strip the truck has trapped 86 mph through the eighth-mile, despite David fighting traction issues and having to launch with very little boost.


1997 Ford F-250

Owner: David Keyser
Hometown: Roxboro, North Carolina
Odometer: 196,700 miles
Engine: 7.3L Power Stroke
Short-Block: Factory crankshaft, Irate Diesel Performance competition main cap girdle, ARP main studs, Riffraff Diesel Performance welded piston oil jets, Manley Performance forged-steel rods, Irate Diesel fly-cut standard bore pistons, Colt Stage 2 cam with welded cam gear, Fluidampr, ATS Diesel billet flex plate, Mishimoto radiator
Heads/Valvetrain: Crutchfield Machine mild porting and performance valve job, Power Stroke Products 165-ppi HD beehive valve springs and retainers, Smith Brothers 0.120-inch wall 4130 chromoly pushrods, Eco Diesel Dynamics cryo’d factory rockers, ARP head studs
Fuel: Full Force Diesel 350/200 hybrid injectors, Irate Diesel OBS fuel system with Walbro lift pump and regulated return
Oil: Swamps Gen3 high-pressure oil pump over factory 15-degree HPOP, DieselSite high volume low-pressure oil pump
Air: Irate Diesel T4 turbo mounting system with stainless steel up-pipes and intercooler piping, BorgWarner S472 SX-E, CSF intercooler, Vibrant Performance clamps
Exhaust: Irate Diesel 3-inch downpipe, 4-inch aluminized system to 6-inch tip
Electronics: Power Hungry Performance Hydra Chip with Jelibuilt Performance custom tuning
Transmission: E4OD with billet input shaft, 6-pinion steel planetaries, Alto clutches, Twisted Diesel valvebody, RevMax 1,700-rpm stall triple disc converter, Derale Performance flow-through pan and auxiliary transmission cooler
Horsepower: 687 rwhp (dyno)
Torque: 1,279 lb-ft (dyno)
Tires: 285/50R20 Nitto NT420S
Wheels: 20×12 American Force polished Blade SS8
Suspension/Axles: Homemade traction bars with bolt-on mounts, Yukon 3.55:1 ring and pinion, Grizzly locker