Inside a 6.6 Duramax L5p!
General Motors first introduced the 6.6L Duramax V-8 diesel engine for its ’01 Chevrolet and GMC light trucks. GM cooperatively designed and built the engine with Isuzu to replace the 6.5L oil-burner that was discontinued the year prior. This new engine marked a leap forward in the design, technology, and performance of GM’s diesels, as the indirect Bosch injection and two-valves-per-cylinder cast-iron heads of the 6.5L were replaced with a 32-valve, high-pressure Bosch common-rail, direct-injection diesel V-8 with aluminum heads.
The LB7 laid the groundwork for all the GM diesel engines that followed it. Subsequent generations included improvements that yielded more reliability, improved emissions, and more power, but they were essentially the same engine through and through.
The 6.6L Duramax L5P is an entirely new engine. The development of this fifth-generation V-8 is more of a rebirth than an evolution. Every single part, down to the nuts and bolts, is reengineered to be stronger. The only thing it shares with its predecessors is the size of the bore and stroke. GM took all the knowledge gained from the older generations (weak links, trouble spots, design flaws, and so on) and made improvements to make the L5P stronger and more powerful than its forebears. The L5P Duramax produces 445 hp and 910 lb-ft of torque in stock trim, annihilating the 397hp/765–lb-ft performance of the LML engine it replaces.
GM, Ford, and Ram are embroiled in a continuing battle for diesel horsepower and torque war. GM certainly knows the game and has developed the L5P to be a major player in that war. Its robust design will allow the engine to support power increases without worry of compromising its integrity. Getting a Duramax L5P to produce more than 1,000 lb-ft of torque is literally only an ECM reprogram away.