Chevrolet and GMC said a new eight-speed automatic transmission will be standard on 2015 Chevrolet Silverado, GMC Sierra and GMC Yukon Denali/Yukon XL Denali models equipped with the 6.2L EcoTec3 V-8.
The GM-developed Hydra-Matic 8L90 eight-speed is approximately the same size and weight as the Hydra-Matic 6L80 six-speed automatic. Its 7.0 overall gear ratio spread is wider than GM’s six-speed automatic transmissions, providing 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.
With 420 horsepower and 460 lb.-ft. of torque, the 6.2L EcoTec3 V-8 is the most powerful engine offered in any light-duty pickup, and offers a maximum available trailer rating of 12,000 pounds, based on SAE J2807 Recommended Practices. As with other EcoTec3 engines, it seamlessly switches 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.