The turbocharging system on the LB7 is unique compared to all other models, as it uses a fixed-geometry wastegated IHI turbocharger. In 2001, the LB7 put out 235hp and 500 pounds of torque, thanks in part to a 17.5:1 compression ratio, but by 2004 those figures grew to 300hp and 520 lb.ft. For fueling duties, GM turned to Bosch, and implemented the CP3 high pressure injection pump, which was driven by a gear and mounted in the front of the lifter valley to put out a max of 23,000 psi. Like every Duramax that followed, it featured 6.6 liters (or 402 cubic inches) of displacement, a cast-iron block with aluminum heads, four valves per cylinder, and a single turbocharger mounted high in the center of the engine. LB7 Duramax 2001-2004 In 2001, GM teamed up with Isuzu and brought another innovation to the diesel crowd and was first to market with a common-rail direct-injected diesel engine, the LB7. All you need to do is install a longer wiring harness, and you’re in business. You can relocate the PMD to the firewall away from the source of heat, and it will last much longer. Because its an electronic device mounted directly to the pump, it easily gets heat soaked, and can internally fail, which will leave you stranded with a truck that won’t run. The most common issue revolves around the PMD or Pump Mounted Driver which control the injection pump. Though it was never had any real performance potential, the 6.5 is reliable. When combined with the proper gear ratio, the 6.5 could knock down an impressive 21 MPG, while still having enough torque to compete head to head with the Cummins engines of the era. The 6.5 came in both naturally aspirated and turbocharged trim, with the former making 155hp and 340 lb.ft of torque, and the latter coming in at 215hp and 440 lb.ft of torque. The 6.5 was the first diesel engine (in a pickup truck) to come fitted with electronic fuel injection, although the 6.5 used indirect rather than direct injection. To fill the gap in their lineup, GM introduced the 6.5 diesel in 1992, which was a slightly updated version of the 6.2 diesel that had been around since 1982. On the opposite end of the spectrum was the massive 7.4-liter 454 V8 which was much more powerful, but also thirstier, with some drivers getting a best of 12mpg unladen, and 8 when towing. At the time, the most popular option was the TBI 350 gas engines, and they were making around 190hp and could (under ideal conditions) achieve roughly 17 MPG. Now, fast forward to present day, and the Duramax has had to undergo very few changes compared to the competition, and are still at the head of the pack! With all that said, lets take a closer look at each generation of diesel engine that's been graced behind that Bowtie emblem and see what they're all about! GM 6.5 1992-2000 In the early 1990’s GM saw the need for a more fuel-efficient truck engine. Then, they backed it all up with an Allison transmission that seemed indestructible compared to Dodge's 47RE and Ford's 4R100. At the time, common rail fuel injection was still in the testing phases at Cummins, and it wasn't even a thought for Ford (International). The LB7 engine set to change everyone's notion of GM's stance in the light duty diesel market, and they haven't looked back since. Previous to the Duramax, their 6.2L and 6.5L offerings faltered behind the Powerstroke and Cummins offerings in terms of overall power and reliability.
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