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Old 11-11-2012, 09:55 PM
MCSL MCSL is offline
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Join Date: Jan 2005
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Advanced combustion system optimized with 6 million hours of analysis

"The Corvette LT1 represents the most significant redesign in the Small Block's nearly 60-year history building on its legacy to make one of the world's best engines even better," said Sam Winegarden, vice president, Global Powertrain Engineering. "More than just great horsepower, the LT1 has been optimized to produce a broader power band. Below 4,000 rpm, the torque of the Corvette LT1 is comparable to that of the legendary, 7.0L LS7 out of the current Corvette Z06. The LT1 is a sweetheart of a power plant and drivers will feel its tremendous torque and power at every notch on the tachometer."

Increased power and efficiency were made possible by an unprecedented level of analysis, including computational fluid dynamics, to optimize the combustion system, the direct injection fuel system, active fuel management and variable valve timing systems that support it. More than 10 million hours of computational analysis were conducted on the engine program, including 6 million hours (CPU time) dedicated to the advanced combustion system.

Direct injection is all-new to the engine architecture and is a primary contributor to its greater combustion efficiency by ensuring a more complete burn of the fuel in the air-fuel mixture. This is achieved by precisely controlling the mixture motion and fuel injection spray pattern. Direct injection also keeps the combustion chamber cooler, which allows for a higher compression ratio. Emissions are also reduced, particularly cold-start hydrocarbon emissions, which are cut by about 25 percent.

Active Fuel Management (AFM) a first-ever application on Corvette helps save fuel by imperceptibly shutting down half of the engine's cylinders in light-load driving.

Continuously variable valve timing, which GM pioneered for overhead-valve engines, is refined to support the LT1 AFM and direct injection systems to further optimize performance, efficiency and emissions.

These technologies support the all-new, advanced combustion system, which incorporates a new cylinder-head design and a new, sculpted piston design that is an integral contributor to the high-compression, mixture motion parameters enabled by direct injection.

The LT1 head features smaller combustion chambers designed to complement the volume of the unique topography of the pistons' heads. The smaller chamber size and sculpted pistons produce an 11.5:1 compression ratio, while the head features large, straight and rectangular intake ports with a slight twist to enhance mixture motion. This is complemented by a reversal of the intake and exhaust valve positions, as compared to the previous engine design. Also, the spark plug angle and depth have been revised to protrude farther into the chamber, placing the electrode closer to the center of the combustion to support optimal combustion.

The pistons feature unique sculpted topography that was optimized via extensive analysis to precisely direct the fuel spray for a more complete combustion. The contours of the piston heads are machined to ensure dimensional accuracy essential for precise control of mixture motion and the compression ratio.

http://www.corvetteblogger.com/2012/...-presentation/

http://www.corvetteblogger.com/docs/...on_24OC12a.pdf



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