The LB7 Duramax marks the first generation of the powerful 6.6L V8 diesel engine, debuting in 2001 for Chevrolet and GMC trucks. LB7 specs highlight 300 horsepower and 520 lb-ft of torque, common-rail fuel injection, and strong aftermarket support. Often regarded as the best Duramax engine for its simplicity and tuning potential, the first gen Duramax set the foundation for future models.