In the November/December 2004 issue, we presented an inside look at the buildup of a 1989 Silverado hot rod, in which a 4700-pound half-ton 4x4 was given the brawny capability of GM's Duramax 6600 diesel engine and Allison automatic. The plan was to create a unique, fun-to-drive, performance-oriented full-size four-wheel-drive sport truck with a modern diesel powertrain.
When running stock programming for 300 horsepower and 520 pound-feet of torque, quarter-mile performance already was excellent at 15.3 seconds and 98.5 mph. The speed at which power can be ramped up with these modern diesels was difficult to imagine just a few years ago. In addition, there are now a variety of aftermarket power products available to take performance to the next level and beyond.
Most of the aftermarket power modules and programmers available for the Duramax stay within the 90-150-horsepower level that tests the torque limits of the Allison, while not producing excessive (and obnoxious) levels of exhaust smoke. In this truck, a 150-horsepower Edge/Attitude module will push performance to a 13.7-second ET and 107 mph in the quarter mile. The difference between running in 2WD and 4WD amounts to about 0.2 second at this power level, with lower ET's coming in 4WD, but with slightly higher trap speeds (109 mph) in 2WD. This is with an otherwise untouched engine and transmission.
Moving beyond the 150-horsepower level reduces the field of available products, leaving us with a competition power module or a custom programmer. It takes an ability to produce a lot of black exhaust smoke to make big power. These products can deliver fuel equivalent of 200-220 additional horsepower, which is too much for street use and way too smoky to be practical without further vehicle modifications. However, when used with a competition module or programmer, the right amount of nitrous will add 270-320 additional rear-wheel horsepower above stock--with a lot less smoke. Depending on the combination of components and how an individual engine responds to tuning, the Duramax could be producing more than 600 horsepower and 900 to 1000 pound-feet of torque.