What would you say if we told you we’re going to start giving the older diesel engines some shine? Would you call us crazy or believe we’ve completely gone off the deep end? Or, would you applaud the move and admit you’ve been hoping we would finally get around to including that type of coverage in these pages?
Before those questions get misconstrued and transmitted across cyberspace like a four-alarm blaze, let’s clarify: Diesel Power is NOT changing format to “old school, all the time.” However, for this report and a few that will follow, the older platforms are being put in the spotlight. “Why?” you ask? We’re doing this because despite how undeniably wonderful the newer oil-burners are, we believe old diesels still have plenty of relevance in the diesel arena.
And, based on the comments and questions about Ford 7.3L Power Stroke, GM 6.6L Duramax LBZ, and 12-valve 5.9L Cummins engines we read in diesel enthusiast forums and our own social media, there’s no reason we shouldn’t revisit their performance every now and again and detail what some of the options are for increasing a classic’s horsepower and all-important torque.
When Ford partnered with Navistar to offer the 7.3L Power Stroke engine in 1992, it was a vast improvement over the previous 7.3L IDI diesel. The biggest advantage was that the new engine was equipped with a turbocharger. Basically, it was a new powerplant with the same displacement as the earlier IDI, but it also had several other improvements. The early 7.3L-powered trucks were the last of the F-Series ¾- and 1-ton pickups. In 1999, Ford introduced the Super Duty name for its new line of F-250 and F-350s. Of course, there was some overlap during the Super Duty’s early production years, and both the old-body-style (commonly referred to as OBS) F-250/F-350 and new-body-style trucks existed with 7.3L powerplants. As a ’95, our truck, the F-350 better known as Big White, is an OBS rig.
We want to turn up the power of our F-350’s stock 7.3L. Of course, the turbocharger is arguably the main piece of the performance puzzle, especially for an engine that theoretically isn’t known for being a diesel with “hot-rod” potential, as the mechanical 5.9L I-6 Cummins engines are. However, the challenging thing about upgrading an OBS Ford’s turbo is that finding a higher-performance replacement is not easy.
We explained our idea and interest to Clint Cannon, owner of ATS Diesel Performance in Arvada, Colorado. It’s a well-known fact that Ford’s 7.3L Power Stroke is a veritable workhorse in stock trim. But, as it is for most engines, there’s additional horsepower and torque that can be gleaned from the original powerplant. For the sake of work efficiency (Big White tows a well-loaded enclosed race trailer, hauls parts, and carries your editor to Diesel Power Central every day) and general driving fun (on the freeway or at the dragstrip), we’re interested in bringing the best out of our project truck’s original engine.
Clint suggested we install ATS’s Aurora 3000 turbo kit for 7.3L Super Duty trucks, as it’s almost a perfect fit for the earlier 7.3L-powered rigs. In truth, only a few things need to be modified (intercooler tubing, downpipe, and such).
Of course, while swapping the turbo, we’re also upgrading other components that must be improved for a complete performance makeover. For example, just prior to starting this exercise, the high-pressure oil pump was replaced with an Adrenaline HPOP from DieselSite, and the low-pressure fuel pump is being replaced with a frame-mounted lift pump system from Bean’s Diesel Performance. Larger injectors are also a must, and Performance Injection Systems 160cc 30-percent-over squirters are the pieces we’ve selected to replace the original 98cc single-shot injectors. To ensure longevity for Big White’s engine, the original cylinder-head bolts are being swapped with ARP head studs.
Once the turbo and fuel system upgrades are complete, we’re remapping the ECM’s fuel and timing strategies with a Hydra Chip from Power Hungry Performance. This versatile, user-friendly chip and software bring tuning pre-’96 OBD I Ford diesels into the modern age of using the Internet and a laptop computer to download tunes to the chip.
It’s quite clear the truck is old, and its 7.3L Power Stroke engine is designed more for low-rpm consistency than it is for being able to easily pump out four-digit horsepower. With the purchase prices for many of the newer diesel pickups being as high as $80,000 for some top-of-the-line models, investing between $7,000 and $10,000 (as budget permits, and sometimes less) in an older truck’s performance is a very popular trend.
We’re hopping up Big White’s engine with an upgrade package that isn’t really “new” for 7.3L Power Strokes. It’s a tried-and-true combination of parts that has been featured in these pages before, as well as discussed in many online forums and social media. According to Clint, the established “safe” performance threshold for stock 7.3Ls is approximately 450 hp and 850 lb-ft of torque. Yes, those parameters can actually be stretched a little farther, but keeping the values below 500 hp/900 lb-ft helps ensure the engine’s towing performance and acceleration remains consistent for a long time—and the changes aren’t so radical that we’ll need to watch for connecting rods suddenly exiting the engine block whenever we go hard on the skinny pedal.
We drove the F-350 1,000 miles from Los Angeles, California, to the ATS headquarters, where the stellar technician team of Mark Sanders and Devin Dahlin handled a surgery that aligns our old rig’s performance with the stock power and torque of many popular later-model diesels.
With updates completed, we ran Big White on ATS Diesel Performance’s chassis dyno. As you can see per the graph, the results are definitely impressive. It’s important to note that we dyno’d the truck using pre-programmed, “canned” ECM calibrations that are included with the Hydra Chip for 7.3L Power Stroke engines. Big White’s chip has since been upgraded with custom programs, one of which (140hp Xtreme) has taken the modified engine to the 425hp, 850–lb-ft-of-torque zone.
The proof is definitely in the dyno results. Before receiving any of the upgrade parts, our ’95 Ford F-350 laid down baseline dyno numbers of 224 hp and 425.96 lb-ft of torque (note that Big White was previously equipped with a K&N cold-air intake system and an air-to-air intercooler), slightly better than Ford’s claim of 210 hp and 425 lb-ft for ’95 7.3L Power Strokes.
With the ATS Diesel Performance Aurora 3000 turbo and other upgrades installed, power was up significantly. During our first dyno run with the modifications and the Power Hungry Performance Hydra Chip set on the “Stock” ECM calibration, gains were an impressive 305 hp and 610 lb-ft of torque. This jumped to a whopping 395 hp and 787 lb-ft when the Power Hungry Hydra chip was added to the mix using the 60hp “Daily Driving” setting. While we did load Power Hungry’s pre-programmed 100hp tune into the processor and performed a “glory pull” that produced 410 hp and 830 lb-ft of torque, the program was immediately dialed back after the dyno hit for daily driving.
Road and Track
While seeing performance gains from upgrades on the dyno is always cool, the proverbial “buck” really stops in the driver seat. As we noted earlier in this report, Big White was driven to and from Arvada, Colorado, from Editor KJ Jones’ home in Southern California, a 1,000-mile journey each way.
In stock trim (with the exception of a K&N cold-air intake system and intercooler), our ’95 Ford F-350 made the trip to Colorado without experiencing any problems, with an average speed of 60 mph and 14.5 mpg fuel economy. On the return trip and using the 60hp tune, average speed increased to 70 mph, with the truck now feeling more willing and almost eager to go faster, even on all the steep grades in the thin air of the Colorado Rockies. Fuel mileage for the circuit remained 14.5 mpg, which is very impressive, considering the upgraded fuel system and injectors.
Driving Big White “hopped up” is a dramatically different experience, especially with custom ECM calibrations that were created after consulting with Power Hungry Performance a few weeks after KJ’s return to Southern California. Throttle response, acceleration, and turbo spooling are all improved (with only the Hydra Chip’s “Towing” tune engaged, the needle on the boost gauge literally snaps past 25 psi the moment you step down on the hammer). The truck is very quick on the street, and now, with greater ability to pass traffic without running out of steam, Big White is a lot of fun to drive on long freeway runs—with and without a loaded trailer.
Since dragstrip performance is also a major qualifier for power and torque gains, KJ tested the F-350 at Auto Club Dragway, a quarter-mile track in Fontana, California. After running an 18.25-second e.t. at almost 77 mph (before the upgrades), using Power Hungry’s custom 80hp “Performance” tune, our 8,400-pound truck’s quarter-mile time dropped to 15.97 seconds at 86.57 mph! It’s important to note that the dragstrip runs were not made in any competitive/race manner. The transmission was left in Drive and shifted automatically, and we did not hold the brakes to build boost before launching or try and cut a killer reaction time. The run probably could have been quicker and faster had those and other variables (140hp “Xtreme” calibration, etc.) been different.
Big White has been consistent and reliable for towing and everyday commuting. The truck is typically driven using the Hydra Chip’s “Stock” setting, unless a trailer, heavy payload, or a need to drive with a little more “spirit” gives us good reason to turn things up.