We've written here several times about the brilliant packaging job that General Motors
has done with its new upcoming 4.5L Duramax diesel
V8. Beyond the basic packaging, the engineers have done a lot of fascinating work on the internals to reduce weight and improve efficiency as well. The main bearing journals that are cast into the bottom of the block are manufactured with a fracture splitting process that makes them stronger and lighter. The block itself also uses less compacted graphite iron, making it lighter and less expensive. The design and manufacturing process also means more open space in the block. The result is easier air flow around the bottom of the block. When the pistons come down in the cylinders, the air needs to move and reduced restriction means lower pumping losses. Since GM
hasn't disclosed specifics about weight or weight savings yet, we'll have to wait to see how much benefit there is. GM does plan to apply the lessons learned from this engine to other future gas and diesel engines.
One thing that is clear is that GM has not over-engineered this engine the way they have with previous diesel engines. When I spoke to high performance engine specialist Gale Banks
about this engine recently, he explained that, unlike the 6.6L Duramax which he has pushed past 1,200 hp, the 4.5L has relatively little room for improvement. It should still provide more than enough power, torque and efficiency for its intended applications, though. We'll be looking forward to pitting this engine against the two-mode hybrid
system when it comes out in the same vehicles.