General Motors is to introduce its first light duty V8 'clean' diesel for North America.

To be manufactured at the GM Powertrain Tonawanda engine plant, the high-efficiency engine will be fitted in pickup trucks under 8,600 pounds gross vehicle weight and the Hummer H2 large SUV, GM said.

The engine is expected to deliver class-leading torque, power and refinement, the automaker added following an announcement event at the engine plant.

The 4.5-litre Duramax-branded V8 turbo-diesel improves engine fuel efficiency by 25%, reduces CO2 emissions by 13% and cuts particulates and NOx emissions by at least 90%, GM claimed.

The new dual-overhead cam, four-valve engine will fit in the same space as a small-block petrol V8. The compact size is due to integral cylinder head exhaust manifolds, integral cam cover intake manifolds and a narrow block.

"This new GM light duty diesel is expected to become a favourite among customers who require excellent towing ability and fuel efficiency," said GM global powertrain and quality chief Tom Stephens. "It will meet the stringent 2010 emissions standards, and it will be compliant in all 50 states, making it one of the cleanest diesel vehicles ever produced."

It will a;sp be GM's first engine to use a selective catalytic reduction NOx aftertreatment system with a diesel particulate filter to help achieve the all-state Tier 2 Bin 5 and LEV 2 emissions standards.

Technical highlights of the engine include aluminium cylinder heads with integrated manifolding; a variable-vane turbocharger with intercooling; a compacted graphite iron (CGI) block for a stronger and lighter engine base (compared to lower-strength aluminium or heavier grey cast iron); and fracture-split main bearing caps and connecting rods for a precise fit.

An electronically controlled, ultra-high-pressure, common-rail fuel system is used, which has the ability to inject fuel five times per combustion event to control noise and emissions will be used.

"This new V8 is not only a clean diesel meeting the toughest emissions requirements in North America, it also delivers an effortless performance feel because of its high torque across the speed range," said GM Powertrain diesel engineering executive director Charlie Freese. "It is also significantly quieter than other diesels on the road today, with noise and vibration performance approaching gasoline V8 levels."

Freese said the new V8's compact size, enabling it to fit in the same space as a petrol small-block unit, gives GM the flexibility to introduce this engine in a wide variety of vehicle applications should there be future market demand.

It is expected to deliver over 310 horsepower and 520 lb-ft of torque in North American-compliant installations.

GM (Opel, Saab, Vauxhall and GMDAT ) currently offers 17 diesel engine variants in 45 vehicle lines around the world and sells more than one million diesel engines a year, ranging from the 1.3-litre four-cylinder diesel engine sold in the Opel/Vauxhall Agila and Corsa, to the 6.6-litre Duramax V8 in full-size vans, heavy duty pickups and medium duty trucks in the US.

GM first introduced the 6.6-litre Duramax diesel in the US in the 2001 model year and said its heavy duty pickup truck market share has jumped nearly tenfold in the six years that the engines have been offered.

Separately, the Associated Press (AP) reported that GM would retool the 3.1 million-square-foot Tonawanda plant, opened in 1937, to make the new engine, on top of several four-, five-, six- and eight-cylinder engines it currently builds with about 1,850 hourly and salaried workers.

AP noted that Tonawanda ranked as the eighth most productive engine plant in North America in a recent report by Troy-based Harbour Consulting and that GM announced last January that the plant would begin producing a new V8 petrol engine in 2009 after GM spends $US300m on renovations and equipment.