General Motors will introduce its new Tier 2 Bin 5 compliant 4.5L V-8 Duramax turbo-diesel (earlier post), in Chevrolet Silverado and GMC Sierra light duty trucks in the 2010 model year.
The new dual-overhead cam, four-valve V-8 diesel engine is expected to deliver more than 310 horsepower (231 kW) and 520 lb-ft of torque (705 Nm), while delivering a 25% engine fuel efficiency improvement versus comparable gasoline engines.
The new V-8 diesel will be GM’s first engine to use a selective catalytic reduction (SCR) NOx after-treatment system with a diesel particulate filter to help achieve Tier 2 Bin 5 and LEV 2 emissions, making it compliant in all 50 states.
Technology in the new 4.5L diesel V-8 includes lightweight aluminum cylinder heads with integrated manifolding; a variable-vane turbocharger with intercooling; a compacted graphite iron (CGI) cylinder block for a stronger and lighter base engine (compared to lower-strength aluminum or heavier grey cast iron); and a fracture-split main bearing cap system. GM has applied for patents on a number of these features and expects to have several patents granted before the engine launches.
Compared to typical production diesel engines, GM’s new 4.5L V-8 turbo-diesel innovatively reverses the flow of air and exhaust gases entering and exiting the cylinder heads. Air enters the engine through ports in the top portion of each cylinder head. Exhaust gases exit inward between the cylinder heads and directly into a turbocharger.
An electronically controlled, 29,000-psi (2,000 bar) common-rail fuel system is also used on the engine. It has the ability to inject fuel five times per combustion event, reducing noise and emissions while enhancing fuel economy.