Diesel Bombers - More news on the 4.5L Duramax

General Motors first introduced the idea of a lighter, more compact Duramax diesel at last year’s SEMA Show in Las Vegas, with the project moving full speed ahead in the subsequent months. GM revealed the top half of the engine late last year – including a turbocharger residing in the space usually reserved for the intake manifold – but kept mum on other engine details. But the wraps have officially come off the new 4.5L diesel, with plenty of details now available.

As with most automotive applications these days, weight was a key concern for GM engineers with the new Duramax powerplant. With that in mind, engineers came up with a new way of holding the engine’s crankshaft. The 4.5L’s crank journals – the part of the engine block responsible for holding up the crankshaft – was created through a unique process called fracture splitting. This technique actually results in greater precision, greater strength and a reduction in cost – both in materials and machining.

This unique design also allows for better air circulations between the cylinder banks. According to GM engineer Charlie Freese, this design reduces pumping losses, resulting in greater performance. “One of the big issues for these modern diesels is the ability to handle the exchange of pressures through the crankcase itself,” Freese told Automotive News.

In fact, the new design is so successful, that GM is looking to use the technique in some of its future gasoline engines.

Further tweaks to the engine’s lower half also resulted in a block that in 30 percent stiffer than any other benchmark design.

The net result is an engine that cranks out 310 horsepower and 520 lb-ft of torques, yet is 25 percent more fuel efficient than a comparable gas engine. The new Duramax is also 50-sate legal.

The new 4.5L Duramax is slated for full-size truck and SUV duty – likely in late 2009 or 2010 – but there have also been rumors that the diesel mill fits nicely beneath the hood of the Cadillac CTS

GM reveals new 4.5L Duramax diesel