This Ain’t Your Grandpa’s OBS Ford
Occasionally, we come across a truck that puzzles us. No matter how much abuse it sees, for some unknown reason, it never breaks anything—even though we know damn well it should. This scenario plays out day after day for Robby Ching and his 7.3L-powered ’97 F-250. The 600-hp old body style Ford knocks down low 12s and makes boosted four-wheel drive launches on a regular basis, yet still sports a 300,000-mile stock bottom end and the front Dana 50 TTB.
“People always say to me: ‘I don’t know how your truck is still holding together,’” he told us.
But it gets better. The truck serves three purposes for Robby: work truck, daily driver, and play toy. After being hooked to a trailer Monday through Friday, it hits the quarter-mile or dirt drags on the weekends, along with being his primary means of transportation. While a lot of big power, stock bottom end 7.3L owners worry about when they’ll scatter parts, Robby is out racking up 3,500 miles a month in his.
Purchased with nothing more than a TS Performance chip and 180,000 miles on the odometer, Robby started modifying the truck immediately. Keeping things simple on the engine, he only upgraded the weak links that the 7.3L Power Stroke valvetrain is known for, along with adding head studs. A set of Comp Cams 910 valve springs replaced the factory springs, and the stock pushrods were ditched in favor of Smith Brothers chromoly units.
“I can drag race it and have a ball on the weekend, and then I’m hooked to the trailer and back to work with it on Monday.” —Robby Ching
To keep the heads from lifting, a set of ARP head studs was threaded in one fastener at a time (a trick used to save the existing head gaskets). To date, the heads have never been off of the block.
Bigger is Better
After sporting a set of 238/100 hybrid injectors for a while, Robby decided to upgrade to a set of Full Force Diesel 300/200’s about 10,000 miles ago. He hasn’t looked back since. The big hybrids receive a steady diet of diesel thanks to a Marty’s Diesel Performance electric lift pump system, complete with a regulated return and Aeromotive regulator. A Stealth SRP1.1 high-pressure oil pump keeps up with the oil demands of the injectors, and completes the HEUI injection system. On the tuning side, Robby navigates through his Swamp’s Diesel Performance tunes courtesy of a TS Performance six-position chip.
Thanks to a T4 turbo mount built by Stroker’s Unlimited, the popular S467.7 charger from BorgWarner sits at the back of the lifter valley. Stroker’s Unlimited also fabricated a set of stainless steel up-pipes and all intercooler plumbing. An aluminum intercooler from a 7.3L Super Duty application is employed to keep EGT cool while towing. Under wide open throttle and in Overdrive, the engine sees more than 60 psi worth of boost.
“More than 60 psi worth of boost.”
Transferring power to the ground is an E4OD automatic that was put together by The Gear Box, a local transmission specialist in Robby’s neck of the woods. A triple disc torque converter from FTI Performance gets things started, while the rest of the four-speed is graced with upgraded clutches, a custom tuned valve body, and billet input and intermediate shafts. It sees full-time towing duty, plenty of boosted launches, and its fair share of vigorous street driving on a regular basis.
While a lot of stock (forged rod) bottom end 7.3L Power Strokes live at elevated horsepower levels a while, Robby’s has been living life at the 500-plus mark for nearly 120,000 miles. It seems to contradict nearly everything we hear about highly modified 7.3Ls. And the fact that he’s never broken or had to rebuild anything in the Dana 50 front end defies all logic, given what he’s put the truck through. To date, it’s been a reliable daily driven workhorse, a consistent 12-second performer at the track, and a complete sleeper on the street. Yes sir, this is definitely not your grandpa’s OBS Ford.
Year/Make/Model: 1997 Ford F-250
Owner: Robby Ching
Hometown: Leonardtown, Maryland
Odometer: 294,287 miles
Engine: 7.3L Power Stroke with ARP head studs, Comp Cams 910 valve springs, Smith Brothers chromoly pushrods
Fuel: Full Force Diesel 300/200 hybrid injectors, Marty’s Diesel Performance 875 Kit (electric fuel system) with Walbro GSL392 pump and regulated return
Oil: Stealth SRP1.1 high-pressure oil pump
Air: BorgWarner S467.7 FMW turbo with race cover, Stroker’s Unlimited custom T4 mount with stainless up-pipes and intercooler piping, 7.3L Super Duty aluminum intercooler
Tuning: Swamp’s Diesel Performance via TS Performance six-position chip
Transmission: The Gear Box E4OD transmission with billet input and intermediate shafts, custom valve body, FTI Performance triple disc torque converter
Horsepower: 595 hp (dyno/track confirmed)
Torque: 1,138 lb-ft. (dyno confirmed)
Tires: 285/75R16 Bridgestone Dueler A/T
Wheels: 16×7-inch factory Alcoas
Axles: 3.55 gears, Warn front manual locking hubs
Suspension: Homemade traction bars, 3-inch 10,000-lb. ratchet straps for front end