Steve Cole is a man on a mission. Since the Duramax was released in 2001 he has been working on optimizing the computer-calibration GM uses to run its newest diesel for more power and fuel economy in a way that retains all of the stock hardware. Lucky for us, Cole isn't hoarding all of his development to himself-he is the owner of TTS Power Systems in Compton, California-and you, too, can upgrade your Duramax with his programming.
How much power, you ask? The consumer version adds around 100 hp and 200 lb-ft of torque to the rear wheels, which is about where the stock Allison transmission starts to slip and cause driveability issues. To remedy this problem, TTS and TransGo have engineered a shift kit and torque converter upgrade to keep the Allison hooking up with more than 500 hp and 900 lb-ft of torque to the rear wheels, which is where Cole's as-yet-to-be-released Xtreme setting raises the power to.
What does 900 lb-ft feel like? We've driven the development truck shown here and can't get over the how fast it is (12.784 quarter-mile at 106.098 mph). It's safe to say we've never driven any street vehicle as powerful! But Cole is concerned that this level of power could break transfer cases, driveshafts, and maybe rear axles, which is why he hasn't offered it for sale...yet.
Three Stages Of PowerThe three power levels each have their own calibration and their own characteristics. The Economy program was designed to improve fuel economy by a few mpg without sacrificing any power. The Tow calibration adds roughly 70 hp and 107 lb-ft over stock and is safe for towing steep grades at max GCWR without dangerous EGTs. The Race mode is for competition or showing off with an extra 106 hp and 211 lb-ft of torque-in our case, about the limit for what the stock Allison can handle.
Finally, Allison Transmission Upgrades!Until now the limiting factor for high-performance Duramax engines has been the Allison transmission. Developed as a joint venture between TTS and TransGo to cope with 500-plus hp, this Allison upgrade kit includes a TransGo shift kit and replacement C2 clutches with steels for $453.62. For severe use, TTS adds a modified Allison torque converter ($1,050) that features more efficient fluid flow and improved lockup clutch engagement without the weight penalty of a multidisc clutch. The converter's mounting lugs are reinforced with a steel torque plate to prevent them from being torn off by extreme engine torque.