Looking to go fast in your diesel-powered ’06-’07 Chevrolet Silverado or GMC Sierra HD? You’re in luck. Thanks to the LBZ Duramax and six-speed Allison transmission being one of the most capable performance combinations to ever grace GM’s ¾-ton or larger trucks, you can squeeze as much as 530rwhp out of it…and sometimes even more than that. What does this equate to at the track? How about high 12’s in the quarter-mile for regular cabs and bottom 13’s for crew cab versions. That’s right, with a few simple mods you can go door-to-door with many of today’s potent sports car offerings.
Unleashing the LBZ’s potential is done in much the same way it is with the LLY and LB7 versions of the Duramax, but beginning in 2006 GM’s 6.6L oil-burning V-8 came with an updated, higher pressure common-rail system (26,000 psi vs. 23,200 psi previously). The new and improved CP3 also moved slightly more fuel than the previous generation (195 to 200-lph). Short-block improvements included more meat cast into the main bearing sections of the block and stronger, forged-steel fractured cap connecting rods. A larger turbo inlet manifold than the choked down version found on the LLY also helped make the LBZ a hot-rod engine right out of the gate.
Below, we’ll show you what you need to open up a can of worms on the street car crowd, without breaking the bank.
EFI Live Tuning and 530rwhp
Once again, EFI Live is the most common way to unlock an additional 250rwhp from your Duramax. Why is this the tuning tool of choice? Available for the Duramax since the mid 2000’s, its software has been studied, learned and perfected by countless aftermarket tuners. Simply put, with a reputable EFI Live tuner in your corner, you can make more power than an off-the-shelf programmer will afford you—and your engine will also be safer. This is because EFI Live calibrators have learned how to make big power while keeping things such as injection timing, duration and cylinder pressure at safe levels.
The Six-Speed Allison Is Tougher—But Not Invincible
For the ’06 model year, the Allison 1000 gained a second overdrive gear, making the commercial-grade automatic transmission a six-speed. Other reinforcements meant that the six-speed Allison could handle more horsepower and torque than the outgoing five-speed. Unfortunately, no Allison 1000 survives the long-term abuse that comes with harnessing more than 1,000 lb-ft of torque while shifting through all of its gears (i.e. drag racing). Sound transmission control module (TCM) tuning and a shift kit can help preserve the life of the six-speed Allison, but not the full 530rwhp the LBZ engine can dish out. A built Allison is the only path to owning a reliable 500-plus horsepower Duramax.
Higher-Flowing Downpipe and Exhaust
Although the factory variable geometry turbocharger, the Garrett GT3788VA, can support an all-out, full-fueling effort from the common-rail system, it is moving a lot of hot air at 530rwhp. And while it can handle the heat, opening up the exhaust flow post-turbo can help in the exhaust gas temperature department. This is especially true if you also install a 3-inch diameter turbo downpipe. Aluminized 3-inch downpipes and 4 or 5-inch exhaust systems are extremely common for ’01-’10 Duramax trucks because they are an affordable way to help evacuate heat. Of course, they also give the trucks themselves a desirable exhaust note.
A Lift Pump Is HIGHLY Recommended
Not gifted with a lift pump from the factory, an aftermarket low-pressure fuel supply system is the best-supporting actor for any ’01-’16 Duramax. As with other pre-2017 Duramax engines, all-inclusive FASS, AirDog and Fuelab systems are extremely popular. They offer improved fuel filtration and air separation, an electric lift pump preset to 8-10 psi and ½-inch diameter supply hose to keep the CP3 fed plenty of fuel volume. On top of the added benefit of keeping positive pressure on tap for the CP3 at all times, aftermarket fuel systems can add as much as 20 hp to your truck’s bottom line.
Light Weight: The Drag Racing Gift That Keeps On Giving
No different from the ’01-’05 trucks that came before them, ’06 and ’07 model year classic body GM’s continued to be the lightest trucks in the HD pickup segment. Regular cab versions of LBZ-powered trucks can weigh-in well under the 7,000-pound mark, whereas a comparable Super Duty of the same configuration could weigh as much as 7,600 pounds. Crew cab models can be made to barely crest 7,000 to 7,200 pounds, too. Less weight to get moving means less horsepower is required to go fast—and the ’01-’07 GM’s were the best example of this. While a Super Duty from the same era needs more than 600rwhp to dip into the 12’s, a Duramax can get it done with 530 to 540rwhp.
The Durable GT3788VA Remains
The variable geometry Garrett GT3788VA turbocharger carried over from the LLY platform, however the compressor wheel was downsized slightly on the LBZ. But like the LLY version, a 360-degree thrust bearing was still employed, which meant optimum support for the compressor wheel end of the turbine shaft. Despite its slight downsizing in compressor and turbine vane height, the LBZ’s GT3788VA still provides for the aforementioned 530rwhp (to as much as 550rwhp) to be made. These turbochargers are tough and rarely ever fail due to overspeeding (unlike the IHI unit on the LB7 Duramax).
12-Second Capability
Should you follow the advice that’s implied above (proven EFI Live tuning, a lift pump and a built Allison six-speed), breaking into the 12’s isn’t hard to do for the LBZ Duramax. With close to 1,100 lb-ft available around 2,000 rpm, a boosted four-wheel drive launch can yield 1.7-second 60-foots, low 8’s in the eighth-mile and high 12’s through the quarter. In regular cab trim, we’ve even seen a few trucks pull off mid 12-second elapsed times.
Don’t Forget Traction Bars
With double the factory power in the mix, axle wrap becomes a concern, which hinders traction and sacrifices driveline longevity. To keep the rear AAM 1150 from wrapping and your GM HD’s 2.5-inch wide leaf springs from twisting, a set of traction bars is a must-have item. They will limit wheel hop, keep the rear wheels planted and digging, and also reduce U-joint and other driveline component wear. Popular traction bars are offered from companies like One Up Offroad and Flight Fabrications. For those after a more discreet look, CalTracs bars are a great option. Along that same line of thinking, help out your GM’s front IFS by throwing in a set of tie-rod sleeves. They’re desperately needed during those hard, boosted, four-wheel drive launches.
Before you lock the transfer case in 4-Hi and get busy doing boosted launches in your Duramax, make sure you install a set of tie-rod sleeves first. Find out why this is so important here.