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There two distinctively different vehicles in the Chevrolet lineup that are immensely powerful. One is the 2015 Chevrolet Silverado 1500 pickup truck. The other is the 2015 Corvette Stingray. Product development is generally most clever when the developers overlook the obvious differences—pickup truck, sports car—and concentrate on the commonalities so that the development is something that has wider applicability. Enter the development of the GM-engineered Hydra-Matic 8L90 eight-speed transmission. In the Silverado*, it is mated with a 6.2-liter Ecotec3 V8 engine. The engine produces 420 hp @ 5,600 rpm and 460 lb-ft of torque @ 4,100 rpm. The engine features a cast aluminum block and heads. It has overhead valves and Clearly, there is a whole lot of activity in the powertrain space at General Motors. These two developments are certainly impressive as to what creativity and dedication can achieve. GM POWERTRAIN ENG NEW TRANSMISSION; NEW ENGINE there's direct fuel injection with Active Fuel Management. In the Corvette, the 8L90 is paired with the LT1 engine. This, also a 6.2-liter V8, produces 455 hp @ 6,000 rpm (or 460 hp if the optional performance exhaust system is on the car) and 460 lb-ft of torque @ 4,600 rpm (or 465 lb-ft, again with the performance exhaust). Again, cast aluminum block and heads, and direct injection. One thing to consider vis-à-vis the trans- mission deployment in the two vehicles is the tremendous difference in size. A Silverado 1500 with a Crew Cab and the small box (5 ft, 8 in.) has a wheelbase of 143.5 in. and an overall length of 230 in. The Corvette, by contrast, has a 106.7- in. wheelbase and is 176.9 in. long. All of which is to say that there is a huge packaging challenge when you're looking to use the same eight- speed transmission in these completely different applications. Kavoos Kaveh, global chief engineer for GM eight-speed automatic transmissions: "It is a marvel of packaging efficiency and driving efficiency that has garnered more than two dozen patents for General Motors." Realize that in the case of both the 2015 vehicles, the eight-speed transmission is going into an existing package. In the case of both vehicles, the 2014 models were equipped with six-speed automatic transmissions (although the Corvette is also available with a seven-speed manual). The point is, they had to develop the eight-speed in such a way that it would (1) fit in both the Silverado and the AD&P; > November 2014 > FEATURE > GM Powertrain Engineers: New Transmission; New Engine > Gary S. Vasilash > gsv@autofieldguide.com 22