The Last HPOP Your 7.3L Will Ever Need

It’s no secret that chasing horsepower with a 7.3L Power Stroke calls for big injectors, and thanks to modern aftermarket HEUI injector technology substantial gains can be had without breaking the bank. However, every factory injection system has its limits—and the 7.3L’s is no different. Once you venture beyond the 550-rwhp range (or, as a general rule of thumb, go larger than a 250cc injector), you run the risk of the stock high-pressure oil pump not being able to keep up. And if you’re unable to maintain high-pressure oil volume being delivered to the injectors, you’ll never realize the full potential of a big set of sticks. To remedy this situation and fully enjoy your truck, you’ll either need to add a higher volume HPOP or run dual pumps.

After being bitten by the performance bug (and with a 5.9L common-rail Dodge at his disposal for daily driving and towing duties), Hastings Foote decided to turn his ’97 F-250 into a play toy. Readying the 140,000-mile, stock bottom end 7.3L Power Stroke for more power called for ARP head studs, Irate Diesel Performance competition valve springs and Smith Brothers chromoly pushrods. Then, with a set of 350/200 hybrid injectors on order, he knew it was time to step up to a higher volume high-pressure oil pump, hence the reason for this article.
In preparation for the big injectors, the engine was saddled with a complete T4 turbo mounting kit from Irate Diesel Performance and a BorgWarner S471. Equipped with a cast 71/100mm compressor wheel and the common 74/83mm turbine wheel, the S471 was also spec’d with a 1.10 A/R exhaust housing—the second largest available—for optimum high rpm flow (i.e., peak horsepower potential).
A steady 65-70-psi diet of fuel supply makes it to the injectors thanks to a competition fuel system from Irate Diesel Performance. The compact, race-ready package incorporates a Fuelab Prodigy pump, -8 fuel line from the tank to the pump and the pump to the engine, and a regulated return system.
To keep fuel free of air and ensure each cylinder sees adequate supply pressure, an Irate Diesel Performance regulated return system is employed. The system consists of 304 stainless steel hard lines, Parker fittings, a Fuelab adjustable pressure regulator, and it also deletes the factory fuel bowl from the lifter valley.
Swamps Diesel’s Gen3 high-pressure oil pump assembly is made up of an industrial-grade Haldex hydraulic pump, a proprietary drive gear that works in conjunction with the factory pump’s drive gear, and a CNC-machined, billet-aluminum high-pressure oil reservoir. Each Gen3 unit is shipped 90 percent assembled and ready to install. Utilizing new mounting bolts, the Gen3 mounts directly above the factory location pump.
The Gen3’s gear pump draws its oil from the reservoir and feeds it to a port at the rear of the factory high-pressure oil pump, which is common to the pump outlets, both cylinder heads, and the injection pressure regulator (IPR). Also note that no second IPR is required. A check valve on the gear pump inlet prevents the factory pump from back-feeding through it when starting the engine.

In recent years, 300cc or larger injectors equipped with 200% over nozzles have proven capable of supporting 650 rwhp or more and provide great streetability with proper custom tuning, but (as stated) they require a larger displacement high-pressure oil pump or dual HPOPs to support them. With a set of 350cc injectors fitted and 200% nozzles on the way, ’97 F-250 owner Hastings Foote readied his highly modified 7.3L’s injection system for the increased high-pressure oil demand that was to follow. His pump of choice was the time-tested Gen3 unit from Swamps Diesel Performance. Of all the big injector 7.3L Power Strokes we come across, nearly 50 percent of them are running this pump. For an HPOP that works in conjunction with the factory pump, installs in just two hours, and supports any size injector on the market, it’s no wonder the Gen3 is so common in the 7.3L world.

With the Gen3’s billet-aluminum, high-pressure oil reservoir replacing the factory reservoir completely, Swamps includes a fresh OEM gasket and new mounting hardware, and accommodates the factory oil pressure and oil temperature sending units. Finding fittings or bolts with their threads coated in paint means they’ve already been tightened or fully sealed prior to shipping (arrow).
The process of installing the Gen3 began with the removal of the mounting bolts for the factory high-pressure oil pump reservoir (arrows). Swamps supplies all new reservoir mounting bolts with its Gen3 pump.
Next, the inspection plug on the top of the factory high-pressure oil reservoir was removed (arrow) in order to suction out the oil. Note that if you opt to pull the reservoir without first extracting the oil you will have a slight mess on your hands, but nothing major.
With the oil suctioned out of the factory high-pressure oil reservoir, the oil pressure sensor was disconnected, along with the engine oil temperature sending unit being pulled from the back of the reservoir. From there, the stock reservoir was lifted off of the high-pressure oil pump.
Thanks to the Gen3 mounting above the factory location high-pressure oil pump, removing the stock high-pressure oil reservoir is as deep as you have to go during the install. Notice the badge on the existing pump: the reputable T500 from Terminator Engineering.
Because the Irate Diesel Performance regulated return fuel system on the engine was originally intended for a single high-pressure oil pump application, its stainless steel lines had to be reworked to clear the Gen3. In addition, the fuel pressure regulator was disconnected from one of the return lines and swiveled out of the way for more working space during the install.
A replacement (OEM) high-pressure oil reservoir gasket is included with each Gen3 pump, which works with all late ’96-03 7.3L engines. On ’94.5 to early ’96 engines, the end user has to cut the supplied gasket to match the original one, and Swamps recommends sealing the rest of the reservoir’s mating surface area with RTV sealant.
The next step entailed removing the hex head plug at the rear driver-side top of the stock location high-pressure oil pump. It would be replaced with this 90-degree 6MB-8MJ fitting that came with the Gen3 pump. The fitting would eventually be connected to the hard line that hangs off the back of the Gen3.
Prior to installing the Gen3, the small amount of leftover oil that had drained into the lifter valley during the factory high-pressure oil reservoir removal was cleaned up. Setting the Gen3 in place on the front cover called for a helping set of hands to keep the hard lines for the regulated return system out of the way.
For ample clearance between the Gen3 reservoir and the serpentine belt, Swamps includes a new thermostat housing neck (shown). We were pleasantly surprised to discover that it wasn’t needed in our install, and we were able to leave the OEM neck undisturbed.
While the supplied Gen3 mounting bolts were installed and fully tightened up as soon as the pump was in place, none of the fittings were snugged up until all of them were connected. The reconnecting of the regulated return fuel lines would be the last step in the Gen3 installation.
To ensure plenty of oil is on tap during periods of high demand, an auxiliary oil feed line is utilized on the Gen3 pump (arrow). Per Swamps’ instructions, the auxiliary oil line inlet was connected to the oil galley at the front of the driver’s side of the block by way of the supplied 4MP-6MJ fitting replacing the factory ¼-inch NPT plug. A braided stainless line carries oil from the block to the Gen3.
A 90-degree fitting with a straight adapter installed in the Gen3’s high-pressure oil reservoir accommodates the factory oil pressure sending unit (shown). The EOT sensor ties into the provided tee that also connects to the auxiliary oil supply line at the rear of the reservoir.
With all fittings finger tight and the braided stainless oil supply hose positioned to our liking, all fittings were tightened up and then double-checked. Before firing up the engine, the high-pressure reservoir was refilled.
When reinstalling the fuel pressure regulator (again, which was part of the previously installed regulated return system), the regulator had to be repositioned with its gauge facing the hood. Otherwise, the 90-degree hard line connected to the bottom of the regulator wouldn’t have cleared the Gen3 reservoir.
Despite having the injection system opened up to atmosphere, the engine started with relative ease, idled great, and it only took a short test drive to purge all air from the system. For those wondering when the factory fuel bowl was ditched, it went by the wayside when the Irate competition fuel system and regulated return were installed. It’s also worth mentioning (and as you’ve probably noticed) that the Gen3 will not work in conjunction with the factory fuel bowl in place.
Given everything that’s been done to the truck at this point (350/200s, competition fuel system, S471, built E4OD and now the Gen3), it should be good for 650 rwhp. And should Foote ever decide to step up to a set of 400/400s (or larger), he’ll have peace of mind knowing that the Gen3 will easily support their high-pressure oil needs.


Irate Diesel Performance

Swamps Diesel Performance

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