Be­cause more fuel means more power

Ultimate Diesel Builder's Guide - - Contents -


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

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