When a truck doesn't fulfill all of the duties demanded of his owner, the next step, albeit bittersweet, may be to consider other options. But what happens when needing a vehicle that tows, hauls a family, provides off-road capabilities, while retaining its fun factor and good fuel economy continuously points you in one direction? For Benjamin Mohn, of Rixeyville, Va., only one vehicle came to mind: the Ford Excursion. Right up to his purchase, he only desired to have a vehicle with reliable towing, while having plenty of seating room for long trips. Little did he know, just like every other diesel driver, once you feel the power of diesel, you crave more.
In 2012, Mohn purchased his 2000 Ford Excursion 7.3 Power Stroke. When he picked up the Ford, which he bought from a close friend, the truck had already been fitted with a 6-inch lift kit, 35-inch tires, a Superchips tuner, an aFe air intake, Banks 1.0 exhaust housing and Big Head wastegate, and a 3.5-inch Banks exhaust system. The Ford was putting out more power, yet retaining a relatively great fuel economy at 18 mpg. Noticing this interesting detail coming from the heavy Excursion, Mohn began researching ways to vastly improve the power of the Power Stroke, while still retaining the surprisingly modest fuel consumption.
"I was really surprised to see the fuel economy on such a heavy truck with the lift and bigger tires," says Mohn. "However, being a car enthusiast and a graduate of the High Performance section at the University of Northwestern Ohio, I knew that there was always room for a little more."
After several weeks of research, Mohn decided it was time to switch to a DP-Tuner, not only for its easy switching of engine performance and tow settings, but also due to the tuner's better matched tuning files for the specific tasks Mohn desired of the Ford. After installing the DP-Tuner chip, he was elated to find that not only was the tuner the right fit for the performance he sought after, but it gave the Excursion instant throttle response and increased fuel economy. Now, with the Ford capable of 22 mpg while shifting through the gears much better than before, the decision was made to take it to the dyno and find out what was really going on under the hood.
After an average number was taken from three dyno runs, the truck produced 261 horsepower and 567 pounds of torque. Hoping to unlock a little more power, Mohn set out to up the ante.
Raising The Bar
The time came to do a little more digging and the owner discovered what could be done to give the Excursion some more pep. In order to keep track of the truck’s improvements, gauges were installed before any serious work was done. While monitoring the truck, Mohn noticed the exhaust gas temperatures stayed at a great acceptable level, reaching a maximum of 1250 degrees Fahrenheit under any condition, but the high pressure oil pump pressure did not. At wide open throttle, the HPOP pressure would level off at 2400psi, which may have represented an acceptable high pressure oil pump spec, but didn't work with Mohn's vision for the Ford.
Another issue that began to surface was turbo surging on the highway, so a rebuild would have to take place to remedy the problem. A Banks wicked wheel, very similar to the early 7.3L Power Stroke stock compressor wheel, was the unquestionable way to go.
Under The Hood
With the turbo performing to Mohn's liking, he decided the next step was to focus more energy and time under the hood to get each system working properly. Noticing that the fuel bowl drain valve was starting to seep and the truck still had the original fuel pump, Mohn decided to build his own custom regulated return setup, adding a high-performing fuel pump. The fuel lines and fittings from Fragola Performance gave him the capability to make the truck 100 percent biodiesel compatible on the fuel supply side up until the injectors. He fitted the system with a 5/8-inch feed line and a 1/2-inch return line. The fuel pump and fuel regulator Mohn turned to were picked up from Fuelab. While rigging the new system together, he decided to do in-tank mods, removing the factory fuel shower, while using Parker Fittings stainless steel tube and Parker A-Lok fittings to wrap that portion of the rebuild up. The next install Mohn made was Strictly Diesel's fuel filter bosses, filters, fuel pump wiring harness, and the fuel pump mount, which made installation much easier and cleaner. The fuel pump and filter mount was hand-crafted to better fit the Excursion’s frame design for a cleaner and easier installation. Once installed, the fuel pressure was set to 65psi using the fuel pressure regulator and running the fuel pump at the recommended half-speed to ensure a long and trouble-free fuel pump life.
The results were again impressive. Mohn found the Ford had a much easier startup and better response in the low rpm range. In addition, the fuel tank mods also eliminated the idle hesitation of the truck when the truck only has a quarter tank of fuel. Last but not least, fuel filter changes became much simpler, while eliminating the common fuel bowl and drain valve leaks.
After physically feeling the positive differences, the fuel system upgrade made, he was very tempted to upgrade the HPOP as well. Looking at the cost, it was a modification that had to wait. One day, however, while coming home from work, it happened. Halfway home, the truck blew apart one of the HPOP lines, which resulted in a great oil mess.
Since the HPOP lines had to be changed, it was time to replace the HPOP as well. He opted for the SRP 1.1 Pump, which increased the HPOP volume and offered a unique ball bearing design, which caught Mohn's attention. After two weeks of wait time and repairs, the Excursion was finally back on the road and giving Mohn incredible results. The truck’s response was incomparable. In addition, the truck pulled much better throughout the power band. It was almost time to hit the dyno again, but before gauging the new power, Mohn found it wise to upgrade the valve springs and push rods to ensure no valve float would occur with the increased boost level which was achieved with the tuner. He installed a set of Diesel Innovations Cromoly pushrods and Comp Cams 910 springs with 0.030 shims to increase the seat pressure to 125 pounds not only on the intake valves, but also on the critical exhaust valves, which could open with high drive pressures from the turbo. It was paramount for Mohn to look at the drive pressures of the turbo, because high drive pressures could result in the exhaust valve lifting from the seat at inappropriate times, resulting in piston to valve contact. After making sure his performance changes didn't affect the engine in any negative fashion, he also decided to finish the work in the engine with a Swamps HVHF IDM, which would ensure the injector solenoids were properly opening and closing at the appropriate times, which also improved idle quality.
Mohn's next trip to the dyno surprised even him. Shockingly, the Ford put down a best of 327 horsepower and 731 foot pounds of torque, representing a great increase over the previous dyno run. Realizing that the only major performance mods added were the fuel pump, the HPOP, and the idm, Mohn couldn't have been more ecstatic with the results. Even while acknowledging the factory injectors and turbo were now the biggest limitations when it came to making more power, the truck averaged 25 mpg on the highway, showing him that his mission to increase power while saving fuel economy had been a success. With the engine work out of the way, it was time to move on to reinforcing the rest of the truck and giving the Excursion new life.
The engine was performing incredibly, but with accumulated increases in power come accumulated increases in stress and heat. Knowing something needed to be done soon, Mohn began his transmission upgrade with the addition of an external transmission filter from DieselSite and a Sonnax Tricumulator Kit. This helped the truck shift a lot better, while making transmission flushes much easier and cleaner. He also installed a 6.0 31 row transmission cooler at the same time to keep the transmission temperatures in check.
With the transmission running smoothly, it was time to add some homemade traction bars to put the traction to the ground. With the help of Ballistic Fabrication, of Tucson, Ariz., Mohn obtained replaceable ballistic joints, weldable tube end, lubrication and axle brackets that answered every demand he had for the perfect traction bar setup. Mohn picked up the traction bar tubing from a local metal shop and went to work creating the Excursion's custom traction bars. When installed, the bars completely eliminated the common found axle wrap. In addition, rear brake vibrations and clunking between gear shifting with heavy loads were greatly reduced.
Mohn made a few last-minute upgrades, which included a DieselSite coolant filter to increase the water pump life and remove much of the unwanted sediments found in the cooling system on many 7.3 Power Strokes, and a set of Mile Marker manual 4WD lockout hubs. Everything had finally come together and gave Mohn the amazing power and fuel economy he was looking for. But the thirst for more performance never ends, and in the future, he plans to upgrade to 250/100 Full Force Diesel single shot injectors, a S468 Irate diesel turbo kit, and a BTS transmission to keep up with the increased power. While some people are fine with what they have, diesel owners know you're never really finished building a diesel masterpiece.
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