It’s the only engine with aluminum heads and one of just two V-8’s on our list, but it’s certainly no less deserving of being here. When the 6.6L Duramax (RPO code LB7) blasted onto the scene in the summer of 2000 for ’01 model year GM HD trucks, it boasted the highest horsepower and torque any diesel pickup ever had before—but that wasn’t all. Beyond its class-leading 300 hp and 520 lb-ft of torque, the Duramax brought common-rail injection, the quietest and cleanest diesel engine operation anyone had ever heard or seen, and the aforementioned aluminum cylinder heads to the pickup truck segment.