Increasing power past factory levels has been absurdly easy since the computer-controlled, common-rail age hit. Still, there are limits to how much you can push the stock parts before they just can’t give anymore. Turbos can only spin so fast and flow so much air, injectors can only move so much fuel, and high-pressure pumps can only maintain so much rail pressure. In both Cummins and Duramax applications, the factory Bosch CP3 pumps can only flow enough fuel to support about 600 hp at the wheels. Adding more fuel via larger injectors or a bigger pulse width tune at more than 600 hp will result in a drop in rail pressure, which leads to less horsepower.
However, there is a solution, and we went down to Pacific Performance Engineering (PPE) in Fullerton, California, to check it out. PPE’s Dual Fueler kit installs a second Bosch CP3 pump above the driver side of the engine, doubling the fuel-handling capacity to 1,200 hp (or even more with nitrous). The second CP3 is computer-controlled with a microprocessor and halves the responsibility of the fuel flow to the injectors, reducing stress on both pumps. In case the factory pump becomes weak or fails, the microprocessor will direct all the responsibility to the second CP3, which means the truck won’t be stranded. The Dual Fueler kit has also recently been granted a CARB E.O. number of D-701 in Duramax (’01 to ’10) and D-701-2 in Cummins (’03 to ’07) applications, which means it’s 50-state legal.
While many people dismiss low rail pressure as a problem they’ll “fix later,” the truth is, the engine could be as much as 50 to 150 hp down without proper fueling. Keeping that in mind, we followed along with PPE’s head technician Miguel Jimenez to see how rail pressure problems could be solved once and for all.
| 1. For the PPE Dual Fueler install, the first step was to remove the air intake. This task was performed by head technician Miguel Jimenez, who would be guiding us along while the kit was installed on a Duramax-powered ’02 Chevrolet.
| 17. When Jimenez finished the Dual Fueler install, the fan, fan shroud, and batteries were all reconnected, and the vehicle was started, checking for clearance and proper operation. After having observed this install, we are convinced this is a task many people could perform in their driveway. There are also full online instructions with wiring and torque specs available at www.ppediesel.com.
