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7.3L Power Stroke Project: DieselSite HPOP & LPOP

Early model year Power Strokes have a different type of injection system than most modern-era light duty diesels have. If you’re a regular reader, you’ve heard me talk about HEUI (Hydraulically actuated Electronically controlled Unit Injection) systems before. HEUI systems, like those found on 6.0L and 7.3L Power Strokes, use high-pressure oil and an electronically controlled mechanical injector to inject fuel at an even higher pressure into the combustion chamber or bowl. Simply put, within the injector, high-pressure oil pushes on a large piston, which then pushes on a smaller piston, pressurizing the fuel and spraying it into the cylinder for combustion. The system has multiple parts, but for the purpose of this article, we’ll focus on the oil side.

OIL PUMPS

On a 6.0L or a 7.3L Power Stroke, oil is taken from the pan via a low pressure oil pump (aka LPOP) where it’s distributed to the turbo, HPOP (High Pressure Oil Pump), oil cooler, and to various galleries that feed the bearings, piston cooling nozzles, etc. The HPOP then takes the oil and pressurizes it, sending between 500 to 3,000 psi of oil to the injectors, depending on engine load. This oil pressure is then sent to the injectors, where it’s used to increase fuel pressure (at the injector tip) up to 21,000 psi for the combustion event. For our 500-rwhp 7.3L project, having a more than adequate supply of oil was extremely high on our list, as it should be for any HEUI engine owner. Outside the fact that larger injectors use more oil than stock (and therefore need more to perform correctly) we wanted to make sure the entire oil system would provide us with all the oil we’d ever need, whether it’s for injection purposes or engine lubrication. To get this extra oil supply, we needed to upgrade to a larger HPOP for the injectors, and we also decided to upgrade our LPOP for a higher flowing version to supply the HPOP and the rest of the engine.

For the new and improved oil pumps, we called upon the HEUI experts at DieselSite. For the injection side of things, DieselSite’s Adrenaline HPOP was chosen. The Adrenaline is a completely rebuilt factory original part that’s been modified to produce a higher volume of oil (which will help larger injectors run correctly, but stock injectors will also benefit from the increased oil volume). It’ll handle substantially higher pressure oil (necessary if the engine is running a hot tune) inside it’s built using bearings instead of bushings as well as many other modifications which were done to increase durability; plus, it ties the two heads’ oil galleries together which allows for a more even oil pressure supply to the injectors. This in turn allows for a better running engine overall. The Adrenaline is a 100% bolt-on replacement for the factory HPOP. No other modifications are necessary to install it.

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To supply the HPOP and other oil systems, we chose to upgrade our LPOP as well. DieselSite’s High Volume LPOP does exactly what the name implies: It flows more oil at a slightly higher pressure. While this modification is not necessary for stock injectors, or even for the 238/80 units we’ll be installing soon, it just makes sense. More oil for every system (lubrication, cooling, and injection) can never be a bad thing.

Installation, while daunting, was fairly simple and straightforward. The only specialty tool we needed when swapping the parts (in the driveway) was a harmonic balancer puller. Other than that, the whole job was done in one lazy Saturday using simple hand tools. DW

HPOP Replacement

1. Removal of the fan and shroud assemblies are necessary for the LPOP install, but not for the HPOP. (although it does make the HPOP job much easier). First thing we did was unfasten the fan from the water pump using a large adjustable wrench. After that was done, the accessory drive belt was removed.
1. Removal of the fan and shroud assemblies are necessary for the LPOP install, but not for the HPOP. (although it does make the HPOP job much easier). First thing we did was unfasten the fan from the water pump using a large adjustable wrench. After that was done, the accessory drive belt was removed.
2. Next we drained the radiator and removed the upper radiator hose as well as the Degas bottle, so the fan and shroud could be removed as an assembly.
2. Next we drained the radiator and removed the upper radiator hose as well as the Degas bottle, so the fan and shroud could be removed as an assembly.

7.3L Powerstroke Performance

3A/3B. The fuel filter housing sits atop the HPOP, so removing it came next. Attached to it are two fuel supply lines to the head that feed the injectors, a supply from the tank, a regulated return back to the tank, and a line to the filter housing drain valve. After removing the lines, the two bolts securing the housing to the HPOP reservoir were pulled and the assembly was then taken off the engine.
3A/3B. The fuel filter housing sits atop the HPOP, so removing it came next. Attached to it are two fuel supply lines to the head that feed the injectors, a supply from the tank, a regulated return back to the tank, and a line to the filter housing drain valve. After removing the lines, the two bolts securing the housing to the HPOP reservoir were pulled and the assembly was then taken off the engine.
4. With the filter housing out of the way, we can now see the HPOP between the two heads. Here you can see we’ve already unbolted its in-and-out oil lines.
4. With the filter housing out of the way, we can now see the HPOP between the two heads. Here you can see we’ve already unbolted its in-and-out oil lines.
5. Before removing the oil lines and unbolting the HPOP, we drained its reservoir of oil using a cleaned out hand pump from a GoJo bottle to prevent a large mess of used oil. A more professional fluid evacuation tool would work just as well.
5. Before removing the oil lines and unbolting the HPOP, we drained its reservoir of oil using a cleaned out hand pump from a GoJo bottle to prevent a large mess of used oil. A more professional fluid evacuation tool would work just as well.
6. All that holds the HPOP on at this point is one bolt located behind this access plate on the front of the engine just above the water pump.
6. All that holds the HPOP on at this point is one bolt located behind this access plate on the front of the engine just above the water pump.
7. When removing this final bolt, we used a small magnet to hold onto the bolts washer to stop it from falling down into the front cover. This bolt is also what secures the gear that runs the HPOP to the HPOP, but the gear is too large to fall into the front cover, so we didn’t have to worry about capturing it.
7. When removing this final bolt, we used a small magnet to hold onto the bolts washer to stop it from falling down into the front cover. This bolt is also what secures the gear that runs the HPOP to the HPOP, but the gear is too large to fall into the front cover, so we didn’t have to worry about capturing it.
8. Before removing the HPOP, we cleaned around it, making sure any contaminants (sand, old oil, etc.) would not fall into the front cover and later wreak havoc on the engine.
8. Before removing the HPOP, we cleaned around it, making sure any contaminants (sand, old oil, etc.) would not fall into the front cover and later wreak havoc on the engine.

DW-1601-LPOP-10

9/10. This is the HPOP oil reservoir (left). Between it and the front cover is a screen filter (right) which stops any large contaminants from entering the HPOP, and later the injectors. DieselSite includes a new filter with the Adrenaline, so of course, we replaced ours.
9/10. This is the HPOP oil reservoir (top). Between it and the front cover is a screen filter (here) which stops any large contaminants from entering the HPOP, and later the injectors. DieselSite includes a new filter with the Adrenaline, so of course, we replaced ours.
11. DieselSite’s Adrenaline HPOP increases oil output over the stock pump enough to handle larger injectors up to 285cc Hybrids. It’s also built much stronger and can handle substantially more pressure than some tunes request. Among other modifications, DieselSite builds the Adrenaline with bearings instead of bushings to increase durability.
11. DieselSite’s Adrenaline HPOP increases oil output over the stock pump enough to handle larger injectors up to 285cc Hybrids. It’s also built much stronger and can handle substantially more pressure than some tunes request. Among other modifications, DieselSite builds the Adrenaline with bearings instead of bushings to increase durability.
12. Stock HPOP on the left; DieselSite Adrenaline HPOP on the right.
12. Stock HPOP on the left; DieselSite Adrenaline HPOP on the right.
13. Installation is quite literally the opposite of the factory HPOP removal.
13. Installation is quite literally the opposite of the factory HPOP removal.
14. Before reinstalling all oil and fuel lines, we replaced their gaskets with new ones that we picked up from DieselSite.
14. Before reinstalling all oil and fuel lines, we replaced their gaskets with new ones that we picked up from DieselSite.

LPOP Replacement

1. Here’s DieselSite’s High Volume LPOP. It and the factory one look almost identical, except the DieselSite part has fewer lobes, which gives it the ability to flow more oil without any negative drawbacks.
1. Here’s DieselSite’s High Volume LPOP. It and the factory one look almost identical, except the DieselSite part has fewer lobes, which gives it the ability to flow more oil without any negative drawbacks.
2. The LPOP runs off the crankshaft and is located behind the harmonic balancer, so the first step is getting it out of the way.
2. The LPOP runs off the crankshaft and is located behind the harmonic balancer, so the first step is getting it out of the way.
3. The large 15/16-inch bolt keeps the balancer in place. Cranking on the balancer bolt to remove it will only result in the engine turning over. We used a large pry bar between the teeth on the flexplate and the bellhousing to stop the engine from turning while we removed the balancer bolt. There’s a specialty tool designed to do this, but our technique worked extremely well.
3. The large 15/16-inch bolt keeps the balancer in place. Cranking on the balancer bolt to remove it will only result in the engine turning over. We used a large pry bar between the teeth on the flexplate and the bellhousing to stop the engine from turning while we removed the balancer bolt. There’s a specialty tool designed to do this, but our technique worked extremely well.
4. The balancer is also pressed onto the crankshaft, so it will not just slide right off once the bolt has been removed. A three-prong puller must be used.
4. The balancer is also pressed onto the crankshaft, so it will not just slide right off once the bolt has been removed. A three-prong puller must be used.
5. Balancer out of the way, here’s the factory LPOP.
5. Balancer out of the way, here’s the factory LPOP.
6. The pump cover is held on with four bolts: Once removed, the cover simply slides off leaving the inner and outer portions of the gear pump LPOP.
6. The pump cover is held on with four bolts: Once removed, the cover simply slides off leaving the inner and outer portions of the gear pump LPOP.
7. Next, the pump gears were slid off the crank, and all surfaces were thoroughly cleaned in preparation for the DieselSite High Volume LPOP.
7. Next, the pump gears were slid off the crank, and all surfaces were thoroughly cleaned in preparation for the DieselSite High Volume LPOP.
8. Pump gears and cover are installed separately. Before installing the gears, they were placed in an oil bath to make sure all surfaces were thoroughly covered in oil.
8. Pump gears and cover are installed separately. Before installing the gears, they were placed in an oil bath to make sure all surfaces were thoroughly covered in oil.
9. Pump gears were then installed onto the crankshaft. Orientation doesn’t matter here, as bolting the cover on will align everything.
9. Pump gears were then installed onto the crankshaft. Orientation doesn’t matter here, as bolting the cover on will align everything.
10. Pump cover installed.
10. Pump cover installed.
RESULTS:

Once both parts were installed, we changed the oil to prevent any damage from contaminated oil using Amsoil’s 15W-40 Premium Synthetic Diesel Oil. We also topped off the HPOP reservoir to make sure the HPOP had a good supply of oil to draw from right off the bat. Before starting the engine, we pulled the IDM fuse (essentially shutting all the injectors off) and cranked the engine over without starting it for three 30-second long sessions with a cooling-off period between each session. We did this to ensure as much oil as possible made its way through the HPOP and injectors to prevent damage upon startup from oil starvation. With the IDM fuse back in, we turned the key over and the 7.3L started quicker than it ever had before. We also noticed the idle was much smoother, and it just sounded like it was running healthier. We took it out for a test drive and the difference was obvious. Due to the stock injectors, the difference wasn’t huge, but the truck did have a noticeable increase in torque and responded to throttle input better than before. We also noticed we were seeing 10-20 psi more of oil pressure. So far, we’re very impressed with DieselSite’s Adrenaline HPOP and High Volume LPOP.  

SOURCES:

DieselSite

888.414.3457

DieselSite.com

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