8L90 Eight-Speed Auto Shifts Quicker Than Porsche's PDK Gearbox

GM 8L90 Eight-Speed Automatic Transmission 1 photo
Photo: GM
When General Motors introduced the seven-speed manual on the 2014 Chevrolet Corvette Stingray, we had a hunch that engineers paid attention to what Porsche has fitted to the 991-generation 911 sports car. However, the German company's super fast PDK is also targeted by GM, namely the all-new Corvette Z06 fitted with the 8L90 eight-speed automatic.
Chevrolet has previously stated that the new unit will offer full-throttle upshifts "up to eight-hundredths of a second quicker than those of the dual-clutch transmission offered in the Porsche 911." We reviewed a number of 911s equipped with the latest iteration of the PDK and boy it's silky smooth and fast. That's why it's a little bit curious how GM developed a transmission that swaps cogs faster than what's heralded as the best tranny out there.

The car on which the new 8L90 will be fitted first is the 2015 Chevrolet Z06, a 650 HP supercharged beast that will go on sale early next year. So it's virtually impossible to verify at the present moment if General Motors is only bluffing or it actually did a faster gearbox than Porsche's PDK unit. GM's chief engineer for transmissions Larry Nitz has recently told Automotive News that thanks to fast electronic solenoids and other controls, the blistering quick shifts of the 8L90 will be faster and smoother in delivery than the dual-clutch automatic of the Porsche 911 Turbo S.

Now that's a very tall statement which will raise the eyebrows of many Chevy and Porsche enthusiasts. Nevertheless, we won't find out if that statement is true until somebody pitches the Turbo S and the all-new Z06 on a long dragstrip. But what we do know for sure is that GM's 8L90 is made up of lightweight yet tough materials such as aluminum and magnesium to keep its weight low. In fact, the whole ensemble weighs almost 8 pounds less than the paddle-shift six-speed automatic fitted in the 2014 Chevrolet Corvette Stingray, marketed as the Hydra-Matic 6L80.

Last but not least, various official or less official reports hint that the eight-speed 8L90 will replace the Hydra-Matic 6L80 on the 2015 model year Chevrolet Corvette Stingray, as well as a suite of other 2015 model year GM vehicles: the Chevrolet Silverado and Tahoe, GMC's Sierra and Yukon as well as the Cadillac Escalade, virtually any GM model fitted with the naturally aspirated LT1 6.2-liter V8 engine. Chances are that the 2016 Chevrolet Camaro will also benefit from the superfast shifts of the 8L90.
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About the author: Mircea Panait
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After a 1:43 scale model of a Ferrari 250 GTO sparked Mircea's interest for cars when he was a kid, an early internship at Top Gear sealed his career path. He's most interested in muscle cars and American trucks, but he takes a passing interest in quirky kei cars as well.
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