GM claims the new eight-speed is faster than most dual-clutch designs.
April 7, 2014
By: Nick Saporito
DETROIT - Chalk this up as an instance of confirming what we already knew: the Corvette Stingray is getting the Z06's eight-speed automatic transmission for 2015. The new eight-speed replaces today's six-speed automatic carried over from the C6 Corvette and GM claims this GM designed and built eight-speed is faster than most dual clutch transmissions.
According to GM, the 8L90 eight-speed should contribute up to 5-percent greater fuel efficiency versus today's six-speed. Chevrolet says EPA fuel economy test results for the 2015 Corvette Stingray are still pending and will be announced later.
The 8L90 is based on the same transmission that will be offered in the balls-out 2015 Corvette Z06, but it has unique clutch and torque converter specifications to match the lower torque figures in the Stingray's LT1 V-8.
Like most GM automatics, the 8L90 offers full range manual shift control via steering wheel paddles. GM engineers say the manual shift mode performs on-par with most dual-clutch transmission designs, but has the trademark smoothness that GM automatics are known for.
The 8L90 is apparently so quick that it can execute up to 160 commands per second. Wide-open throttle upshifts are executed up to eight-hundredths of a second quicker than those of the dual-clutch transmission offered in the Porsche 911.
During the reveal of the Corvette Z06 Corvette Chief Engineer Tadge Juechter was asked why Corvette did not utilize a dual-clutch transmission. His response, "There is no dual-clutch transmission in the world that can handle this car's [Z06] torque and fit the size requirement - plus this eight-speed is as fast."
The new 8L90 is built in GM's Toledo, Ohio transmission plant.