D-MAX FUEL SYSTEM UPGRADE
Because more fuel means more power
Last issue, the crew at Advanced Injection installed a complete, power-packed upgrade on our well-worn ’01 Chevy Duramax—originally, our off-roader project LB7. The upgrades included a Banks Power Big Hoss Bundle, including the larger Techni-cooler intercooler, mandrel-bent, large-diameter boost tubes, Monster exhaust system, Bighead wastegate actuator and Six-gun tuner with the Banks iq interface, as well as a Fleece Performance Engineering LB7 63mm Cheetah turbo and Pro Fab Performance downpipe.
With more than 360,000 miles on the clock, the old dog has been running awesome after the install, but we can tell that the high-mileage LB7 CP3 high-pressure pump is weak and that we are leaving some power on the table. To remedy the situation, we once again turned to our friends at Fleece for a remanufactured LBZ CP3 that delivers more fuel than the stocker LB7 pump. We also picked up an Airdog II pump and filter system from Pureflow to deliver plenty of well-filtered #2 fuel to the CP3.
Before we made the fuel system upgrades, we took our 2500 HD to DC Chassis Dyno, in Brownsburg, Indiana, and strapped it down to the Dynojet chassis dyno to see what the last round of performance modifications did.
With the Banks iq turned up to SL (Speed Loader) level, the truck put down peaks of 474.99 horsepower and 872.21 lb-ft of torque through the truck’s massive 37-inch Goodyear tires. Using the DSP-5 EFILIVE custom tuning from Fleece Performance, it delivered 513.80 horsepower and 940.40 lb-ft of torque. The Banks Power, Fleece Performance Engineering and Pro Fab Performance combination really woke up our high-mileage LB7 Duramax— especially when you consider that we are putting the power down through stock 3.73 gears with 37-inch-tall tires that weigh in at about 114 pounds each. The combo delivered about twice the horsepower compared to stock LB7 Duramaxes we’ve seen on a chassis dyno.
After running on the rollers, we headed across town to Fleece’s shop to install our fuel system upgrades. We were installing the AirDog II and LBZ CP3 on our older LB7 Duramax, but the same techniques would be used for newer-model Duramax trucks, too. Since the Airdog pump system offers integrated water separation and 2-micron filtration, we chose to use it as the primary fuel filtration.
Fleece technician Jake Richards first went to work removing the old CP3 and installing the LBZ CP3. Since our truck has the Fiberwerx onepiece hood installed, he chose to remove both the hood and grille to make it easier to work on and around the engine. The CP3 is located in the lifter valley of the engine block and requires removing just about everything on the top or front of the engine. A CP3 swap is not for squeamish Diyers who are afraid of getting their hands dirty, but the results are well worth the effort for those willing to put in the work.
The Airdog installation is very straightforward and doesn’t even require dropping the fuel tank on Duramax trucks, since GM provides large-diameter fuel lines from the factory. Disconnecting the factory fuel line fittings is the most difficult part. The supplied hoses have mating fittings pre-installed, but to work with our mounting location, the hoses needed to be shortened. The kit also supplies union joints to shorten the hoses, so it worked out.
Even the wiring harness is easy to install with simple power and ground connections, as well as a fuse tap installed in the fuse block. Then it is just routed down to the pump that Richards mounted high on the inside of the frame to keep it out of harm’s way when we are flying around off road.
The total installation time was about six hours, including various interruptions and photography slow-downs. But Richards and the rest of the crew at Fleece Performance are seasoned diesel technicians who have performed these upgrades on many trucks. If you plan on doing this installation yourself, be sure to give yourself at least a full day.
The day after the installation, we headed back over to DC Chassis Dyno to see the fruits of our labor. With the truck strapped down to the Dynojet rollers once again and Chase Fleece behind the wheel, we made several dyno pulls—and were very happy with the results. Using the Banks Power iq and Six-gun tuner, we saw peak horsepower rise to 493.51, with peak torque measured at 961.12 lb-ft; these were peak improvements of 18.52 horsepower and 88.91 lb-ft of torque.
However, the peak numbers only tell part of the story. Comparing the before and after dyno graphs, you can see an improvement of about 50 hp from 1,750 to 2,100 rpm and around 100 hp from 2,100 to 2,600 rpm. There was a similar boost in torque across the same rpm ranges, where you really feel it in the seat of your pants. The Banks tuning is clean, even with the additional fuel delivery of the LBZ pump, so you don’t have to worry about blacking out the street each time you mash the throttle.
Using the custom Fleece Performance EFILIVE tune, we saw our best dyno pulls of the day: peaks of 543.63 hp and 1,006.74 lb-ft of torque, for peak improvements of 29.83 hp and 66.34 lb-ft of torque. The Fleece tune had its best improvements in the 2,200-2,800rpm range, with about 75 more hp and about 150 lb-ft more torque.
We are very happy with the performance of our 360,000-plus-mile LB7 Duramax—especially considering that we still have stock injectors in the heads and the bottom end is still completely stock as well. We’re going to enjoy the engine in the truck the way it is while we concentrate on some other areas, such as the body, interior and gearing.
But don’t think we’re done with the LB7. We’ll probably throw some performance rods and new pistons in the bottom end before installing high-flow injectors and a modified CP3, or maybe even dual CP3S, in an effort to crank even more power out of this well-worn Duramax. Stay tuned! UBDG