Project Street-Max: 2006 GMC Duramax

Part 4: Making 600 RWHP

Mike McGlothlin
Mar 1, 2012
Photographers: Mike McGlothlin, John Zibutis
Project Street-Max is taking a turn toward serious for the final installment. This month, we’re upgrading our ’06 LBZ’s injector nozzles and CP3 at Knoles Performance Solutions and also having the truck dyno-tuned by Fleece Performance. First, the factory injectors were sent to Fleece, where they were fitted with 60 percent larger nozzles. To keep up with the larger nozzles and maintain rail pressure, we shipped the factory CP3 to Motorsport Diesel (formerly Wicked Diesels), where it was transformed into one of the company’s infamous stroker pumps.
Photo 2/13   |   project Street Max Part 4 2006 Chevy 2500 4x4 Burnout
With the engine buttoned back up, Fleece tied the combination together using EFILive software while on a dyno, effectively optimizing the truck’s power, driveability, and fuel economy. The final step was heading back to Randall’s Performance for one last dyno appointment.
Between the fully built Sun Coast transmission, necessary fuel modifications, and the 68mm Cheetah turbocharger, we think we’ve built a max-effort, street-driven, late-model Duramax. And by limiting the truck’s power level to less than 650 hp, the LBZ engine under the hood is still well within the safe zone. We’ve also included a recap of what it took, parts-wise and dollar-wise, to get our Sierra to the 600-rwhp mark. If you’re looking for the ultimate, daily-driven Duramax yet aren’t quite ready for a built engine, this is the setup for you.
Photo 3/13   |   In order to be fitted with 60 percent larger nozzles, we sent our stock injectors to Fleece Performance as complete units. This way, they could all be batch-tested and balanced to flow accurately once the nozzles were installed.
Stroker CP3 Injection Pump
Many areas of the LBZ CP3 are addressed when Motorsport Diesel converts one to a stroker pump. A 2mm increase in stroke equates to a 25 percent increase in displacement, which is pretty substantial. Other modifications include enlarging the ports on the gear-supply pump (which is responsible for providing fuel to the plungers at high pressure) to match the passage size of the pump body, adding 50 percent more to the lift of the delivery valves, and several other things that are kept proprietary. Like the 60 percent nozzles we went with, its stroker pump can also support trucks making in excess of 800 hp.
Photo 10/13   |   project Street Max Part 4 cp3 Injection Pump
*Motorsport Diesel does not utilize used cores to build its stroker pumps, although some exceptions can be made for fresh, wear-free pumps. The fact that our pump had just 50,000 miles on it made it an exception to the rule (although it was thoroughly inspected and any questionable components were replaced).
The farther you move away from the stock hardware, the more important it is to make sure your modifications work in conjunction with each other. This is where custom-tailored, EFILive tuning comes in—you meet with your tuner in person to get the most out of your given combination of parts. What’s even better is conducting your tuning on a chassis dyno, where you can track your progress, tweak and monitor key parameters (timing, pulse width, rail pressure), and make sure you obtain the horsepower number you’re after.
Photo 11/13   |   project Street Max Part 4 dyno Tunning The Truck
We met up with Brayden Fleece of Fleece Performance at DC Chassis Dyno in Brownsburg, Indiana, to not only make sure we cracked 600 rwhp, but to make sure we did it as safely as possible. Thanks to the larger nozzles, less timing and duration (pulse width) can be commanded in the tuning, all while making more horsepower. The combination of running a maximum of 30 degrees of timing and 2,650 microseconds of pulse width led to an impressive 642 hp and 1,180 lb-ft on DC Chassis Dyno’s DynoJet 224xLC dynamometer. With the stock nozzles, our maximum horsepower tune was commanding 32 degrees of timing and 3,200 microseconds of pulse width (an earlier start of injection, with a longer injector on time).
Street-Max Recap
(Part 1, Sept. ’11)
Air intake: K&N with Amsoil dry filter
Exhaust: 4-inch MagnaFlow single exit (stock downpipe)
Fuel System: AirDog 100-gph lift pump
Transmission: Sun Coast GMax 6-pac, 1058 converter
Horsepower: 254 hp at 3,000 rpm
Total Spent: $3,319
(Part 2, Oct. ’11)
Fuel pressure relief valve: Shim kit
EGR: Blocker plate
PCV: Reroute kit
Tuning: EFILive via Fleece Performance ECM and DSP5 switch
Horsepower: 475 hp at 3,000 rpm
Total Spent: $1,319.99
(Part 3, Nov. ’11)
Turbo: Fleece 68mm Cheetah turbocharger
Exhaust: HX40 downpipe
Emissions System: Full EGR delete
Engine Modifications: Head studs
Horsepower: 525 hp at 3,200 rpm
Total Spent: $3,741
project Street Max Part 4 dyno Chart
  |   project Street Max Part 4 dyno Chart


EFI Live
Auckland, NZ, AK
Fleece Performance Engineering
North Salem, IN 46165
Randall's Performance and Accessory
Gladstone, IL 61437
Knoles Performance Solutions
DC Chassis Dyno
Motorsport Diesel



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