General Motors plans to make a new eight-speed automatic transmission standard on its 2015 Chevrolet Silverado, GMC Sierra and GMC Yukon Denali/Yukon XL Denali models equipped with its new 6.2-liter EcoTec3 V-8 gasoline engine.
The GM-developed Hydra-Matic 8L90 8-speed is approximately the same size and weight as the current Hydra-Matic 6L80 6-speed automatic, the OEM noted in a statement, but its 7.0 overall gear ratio spread is wider than GM’s 6-speed automatic in order to provide a numerically higher first gear ratio to help drivers start off more confidently with a heavy load or when trailering.
The 8L90 also enables numerically lower rear axle ratios, which reduce engine rpm on the highway, the automaker said.
GM added that its 6.2-liter EcoTec3 V-8 engine cranks out 420 hp and 460 lb.-ft. of torque so as to offer a maximum available trailer rating of 12,000 pounds. Introduced with the GM’s 2014 upgrade to its Chevrolet and GMC pickup lines, the EcoTec3 is also deigned to “seamlessly” switch to four-cylinder operation under lighter loads to improve fuel economy.
Additional technical details and the EPA estimated fuel economy will be announced closer to the start of production in the fourth quarter of 2014, the OEM noted.
