Part and parcel of the greatness of the seven-three was its use of hydraulic electric unit injectors (HEUI), which greatly increased oil pressure and made the truck capable of handling loads of power at its behest.

Brief History Of The 7.3 Liter DIT

After years of success with the 6.9 and later 7.3 liter indirect injection diesel, Ford and Navistar decided it was time to revisit the design in the early ’90s. The new engine would be the first computer-controlled diesel in the light-duty segment. While the displacement would remain the same (7.3L), this was in fact an entirely new engine. Ford probably didn’t even realize at the time that this new and improved 7.3 liter would become one of their hottest engines and still something highly sought after, even a decade after they discontinued production.

The 7.3 used a unique injector co-developed between Caterpillar and International. The revolutionary injector used hydraulic multiplication to inject fuel in excess of 23,000 psi directly into the cylinder. At the time, most competitors were lucky to see 18,000 psi through an injection pump. To gain the hydraulic advantage, the 7.3s use a High-Pressure Oil Pump (HPOP) that is fed by the low-pressure oil pump, which increases the pressure up to 3,000 plus psi at high demands.

All of the Direct Injection engines were Turbocharged (DIT) and were introduced mid-year in 1994. The original engines were in the last years of the Old Body Style (OBS) trucks from 1994 to 1997. The turbocharged 7.3L engines were non-intercooled (had what we would consider low boost pressure now, but low to mid-teens was high boost pressure back then) and were fully computerized. If the camshaft position sensor (CPS) went out, the engine died.

Unlike some later computer-controlled engines from other manufacturers, these engines live and die by the computer. Later there was a slight revision of the engine in 1999 when the new Super Duty was introduced (model year 1999, calendar year 1998). The Super Duty featured higher boost pressure and was intercooled. These engines were still rock solid and extremely dependable. That’s one of the reasons they are so highly sought after to this day.

Enough Of The Jiber Jaber – Let’s Talk Dyno Day!

For the high mileage, daily-driven 7.3L-centric dyno day, we wanted a group of true work trucks that get used day in and day out. We cast a net over what is called the Inland Empire in Southern California (an area that is an hour away from the beach and on the other side of the mountains). After getting some great feedback, we narrowed down our picks to six unique individuals with some great trucks. Most are local friends and work at different So Cal diesel shops, including such die-hard diesel organizations as Lewis Built Performance, Axxis Off Road, and American Diesel.

Brandon Shade’s 2000 Excursion

Ed Hatcher’s 7.3 Liter Bio Diesel OBS

Chris Lewis’ 1996 7.3 Liter

Hatcher’s ride has a good look to it thanks to the 6-inch lift with 35-inch tires and Moto Metalwheels. On top of everything, the truck is sporting a custom-built roof rack with 3 HIDs up front. On the underside of things, a Dana 60 High Steer Kit with Heim Joints was installed along with a set of rear Lewis Built traction bars.

Under the hood, the 7.3 is tweaked by a six-position chip from TS Performance. The power is then sent through a custom-builtDyno Trans transmission to a Detroit Locker rear diff.

• Edge CTS Diesel tuner
• MBRP 4-inch stainless exhaust
• S&B cold air intake
• Stock turbo producing up to 23 lbs. of boost
• Mileage: 100,000
• Best run: 289 hp, 523 lb-ft of torque

Brian Hartley, Owner of Axxis Off Road, made sure his Excursion was ready to go for the Dyno Day. Big, white, and the “youngest” of the bunch, the SUV came ready for the showdown. Hartley had his Excursion equipped with an Edge ProductsEvolution CTS Diesel module to give him the performance he wanted, but more importantly, to monitor the vitals. Under the hood, the only upgrade he did was to install an S&B cold air intake.

Giving the truck an imposing appearance not to be reckoned with, Hartley added three-inch lift blocks, Procompshocks, and Weld wheels with Dura Trac tires.

However, Hartley’s ride wasn’t always tricked out, about two years ago, Hartley and his friends were headed down to Mazatlan to have a good time. Out of nowhere, a semi-truck came roaring from the side and plowed into the SUV and trailer, destroying just about everything.

Rather than collect the insurance and go about their merry way, Hartley and his friends took the time out — about six months’ worth — to do the bodywork and fabrication. After seeing its pristine appearance, we couldn’t help but admire the resourcefulness and talent the guys put to use on the project.

Jerry Schuman’s 1997 7.3 Liter

The most spartan of the Power Strokes we had on the dyno, Jerry Schuman’s F-250 rolled into our garage at 356k miles and with hardly an aftermarket part to its name. Nonetheless, it is a true work truck and daily driver that we were after for this round of testing.

The only upgrades consisted of a 3-inch Magnaflowcat-back kit and an Edge Products Evolution tuner. Everything else, says Schuman, was “just tune-up or maintenance.” And with a nice and reliable work truck, we can’t fault the guy for keeping it simple now, can we?

Yet Schuman claims that this truck is nothing to be scoffed at, even though he’s taken lots of flak for keeping it as long as he has. “That truck has towed home every one of my friends at least once, when either they blew up their truck, got in a car accident, or got wrecked while off-roading. So the name that has been given to the truck is ‘Old Faithful’ because she has always been ready to roll.”

Now that the truck has passed hands to a friend of Schuman’s, its legacy of strength, power, and reliability is ready to live on. Let’s just hope that the new owner understands he doesn’t need any fancy bells and whistles to keep Old Faithful running strong.

Paul Christensen’s 2000 F-350

Last but not least, there was Paul Christensen’s 2000 F-350. This big red rig, rolling on 35-inch Toyo M/Ts and 20-inch BMF wheels, had no problem climbing onto the dyno to see where it stood amongst the pack.

The 7.3 liter is able to produce 27 lbs. of boost, thanks to the extra fuel supplied by the TS Performance chip – the same one found on Chris Lewis’ truck – and a cold air intake kit. The F-350 was having fun all day in the sun, whether it was out doing burnouts on the nearby street, or putting up strong numbers on the dyno’s monitor.

• 4-inch straight exhaust with 8-inch tip
• 20-inch BMF wheels
• 35-inch Toyo M/T tires
• Over 25 lbs. of boost in third gear
• Mileage: 256,000
• Best run: 274hp, 467 lb-ft of torque

We want to give a special thanks to all the guys who came out for this event. As we mentioned earlier, this is just the first in a long series we plan on doing until management decides we have to start cleaning the soot off the walls. So stay tuned to Diesel Army and check us out on Facebook.