Terminator HPOS

First off, how about a little tech lesson on how a 7.3L actually works? The 7.3L Power Stroke uses a HEUI-style injector, which stands for Hydraulically Actuated Electronic Controlled Unit Injection. Diesel fuel is supplied to the injectors through fuel rails inside the cylinder heads. A high-pressure oil pump (HPOP), which is gear-driven by the engine, is also used to supply high-pressure oil through the heads to the injectors. When the computer sees that a cylinder needs to fire, a signal is sent to the Injector Driver Module (IDM). The IDM will send a pulse-width signal to the solenoid on the injector. When the solenoid is actuated, a poppet valve inside the injector opens allowing the high-pressure oil to flow inside the injector where it presses against an intensifier piston.

This high-pressure oil action is known as the injector control pressure (ICP). This ICP is what forces the intensifier piston down, which pressurizes the diesel fuel found inside the injector. When the fuel pressure inside the injector reaches a certain pressure the injector pintle will lift off its seat and allow fuel to be injected into the cylinder through the injector nozzle.

So in effect the pressure the HPOP can build will have a strong effect on how that engine runs. Factory specs call for anywhere from 2600-2900 ICP for proper fuel injection and atomization in the cylinder. The 7.3L was produced with two different high-pressure oil pumps: the early models, 1994 through early 1999, were equipped with a smaller 15-degree pump; while the later 1999-2003 truck came with a better performing 17-degree pump. Our truck, being an early 1999 model, had the smaller 15-degree pump.

After the installation of the new Stage II Hypermax injectors, our pump struggled to maintain an acceptable injector control pressure. The pump just couldn't keep up with demands and low ICP can be detrimental to performance. The injectors struggle to fire quickly enough and inject fuel at the proper pressure, meaning low atomization, more smoke, and overall low efficiency. Using our Auto Enginuity scan tool, we were able to data log a few hard wide open throttle runs and saw ICP go as low as 1,235psi with our pump working at nearly 90 percent capacity trying to maintain that. Numbers that low for a sustained time will actually set off the check engine light and a diagnostic trouble code, most often p1211. As we stated before, these trucks were engineered to produce upward of 3000psi, while a good strong pump could do that at say 40-50 percent capacity. Needless to say, something needed to be done with our high-pressure oil system.

A common and somewhat inexpensive upgrade would be just updating to the newer style 17-degree pump. However, even the 17-degree pump could have trouble keeping up with our larger injectors. It's actually pretty common that a truck running a hot chip while still on stock injectors can suffer from low ICP problems. So we opted to install an aftermarket solution. Rather than take our chances of finding a good 17-degree pump, we went ahead and ordered a dual high pressure oil system from Terminator Engineering out of Modesto, CA. A few years back Joey Omlin, owner of Terminator Engineering, and his friend Jeremy Walker tackled the job of finding a resolution for the low ICP problems plaguing the high horsepower 7.3L Power Stroke market. The factory system, while sufficient for a stock truck, was nowhere near enough to support the needs of those pushing the outer limits of
Power Stroke performance.

With that in mind they engineered and designed a dual high pressure oil system that couples two factory OEM pumps together (kind of the same theory behind dual CP3 kits that are so popular with the Duramax and common rail Cummins crowds). The factory HPOP is found in the valley of the engine, right up by the front cover, directly below the factory fuel filter bowl. What Terminator Engineering has done utilizes some of the space left in the valley, placing another OEM pump directly behind the stock pump. Using a machined billet block to connect them, everything will fit with all the factory fuel system components installed. In fact, once the factory fuel bowl is reinstalled, it's almost impossible to see the new Terminator HPOS under there.

Terminator also engineered what they call a Remote IPR block into the pumps. This relocates the factory injector pressure regulator (IPR) valve from the bottom side of the factory pump to the topside, making it easier to get to. This makes for easy servicing and cleaning if the need ever arises, turning a two-hour job of removing the pumps from the truck, into just a 20-minute job of removing the IPR only.

We took our truck down to Wide Open Performance in Sandy, UT, for the installation, but it is definitely a job that can be done in just a few hours on your own. (We need to thank Wide Open for the use of the shop and Terminator's eastern technician, Kenny Zorns, for the help on the install.) We'd expect this install to be a decent Saturday afternoon in the garage for a somewhat mechanically inclined owner.

While the system will still work with the factory fuel system in the truck, install would be much easier if you were to install an aftermarket Regulated Return like ours from ITP Diesel, along with their fuel bowl delete kit. However, by removing the factory fuel bowl, you'll need to install some kind of post pump filtering device. We opted to keep our factory bowl, which didn't present any real issues.

The Terminator Dual Oil System, also referred to as `Big Oil,' will now provide all the oil volume and pressure our injectors will ever need or want. Testing has shown that these pumps could produce upwards of 3800psi if you felt inclined to run that sort of pressure. We would like to mention that this system would still offer a decent performance improvement on a stock injectored truck, while still producing enough oil for the largest 7.3L injectors on the market.

Maintaining a solid 3000-plus ICP under any condition not only improves fuel atomization (meaning better fuel mileage), but will also broaden the power and torque bands substantially. It's power and torque you'll actually feel while daily driving, hot rodding and towing. The improved injection ratio seen from the addition of dual oil pumps will have an effect on actual injection timing, so some change in your tuning is highly recommended.