There aren't many aftermarket modifications that hold up to the claims marketing monkeys put on them. And it's not often that we're able to get our hands on an upgrade that puts our expectations to rest and still keeps delivering. ATS' Five Star converter and Copilot combination is one of those faith-saving mods. With these modifications in place, the Allison transmission's efficiency was increased, which added an incredible 1.85 to the truck's mpg. That gave our LB7 engine damn-near 18 miles to the gallon. Did we mention our Duramax makes 450 hp and more than 1,000 lb-ft of torque? That's right, 18 miles to the gallon, with enough power to haze a set of 38x15.50 Open Country mudders with the stock gear ratio. So, if you did the math, not only would the ATS mods save you money in the long run with fuel economy, but you won't have to replace it like the stock tranny. All that adds up to being paid to run ATS' transmission modifications.
Stock automatic transmissions coupled to an enhanced diesel powerplant will start showing signs of overpowering at about 450 hp and 750 lb-ft of torque. We found the average tranny (Ford, Chevy, or Dodge) gives up the ghost at about 450 hp and 750 lb-ft of torque on its best day. These power levels can easily be reached by simple bolt-ons. An air intake, an exhaust, and a killer programmer is all it takes to get the tranny to start slipping. And after it's happened once, you can rest assured ECM will throw a tranny trouble code sometime in the near future. This is true even with the Allison, one of the toughest of today's Overdrive trannys.
What makes the Allison so tough, you ask? Many new trannys are simplistic derivatives of their predecessors. The 5R110 is Ford's newest heavy-duty transmission, but when it's placed next to Ford's older 4R100, E4OD, and A4LD you can see they have the exact same overall shape, plus they share common components and engineering ideas. Both Ford and Dodge Overdrive trannys have evolved by the simple method of adding the Overdrive to an existing tranny. This is known as a Stack Transmission, and yes, if you lay one of their modern trannys next to its one-to-one automatic predecessor (vacuum-controlled) C6, you'll find many similarities. Similar to how Ford added the Overdrive unit to the front of its C6, Dodge formed its stack transmission by adding an Overdrive to the back of its 727 TorqueFlite.
The Allison is a totally different breed of tranny compared to the old-style Stack Transmission, because the extra gear was not an afterthought. The older transmissions are vacuum-controlled, which meant converting to electronic controls was limited by 50-year-old mechanical engineering. The Allison was fully designed as an electronically controlled Overdrive from the start, therefore all its functionality can be completely controlled by programming. This design is called a Full Synchronized Transmission and was actually used by Dodge on its Caravans, but was labeled the Ultradrive tranny. Much like many new ideas, it was released before thorough research and development could refine it. This plagued the Ultradrive with problems, and Dodge laid it to rest as fast as it was implemented. Not to worry, ATS Diesel has bulletproof mods for all three big truck makers. Because the Dodge and Ford are stack-style transmissions, the upgrade will be slightly different from the Allison upgrades we'll be discussing in this issue.
What does all this mean to the modern oil-burning torque-monger? The answer is a daily driven truck that can sustain 1,000 lb-ft of torque, that's what. After using ATS Diesel's Aurora 2000 turbo (made for towing), new CP3 pump, high-volume electric pump to feed the new high-flow CP3, and the aggressive programming, our Duramax made 425 hp and 1,025 lb-ft of torque on a Mustang chassis dyno. This truck is a daily driver, and the program only gets turned down for an occasional towing. The Copilot's enhanced power management works seamlessly with the ECM. This provides smooth comfortable drivetrain functionality till you lay into the throttle. Then, the shift pressure, torque management, converter lock, and other tranny functions become equally aggressive to match the engine's output.