The 2015 model year introduces the new LT4 6.2L supercharged V-8 engine. The LT4 is the power behind the Corvette Z06. Rated at 650 horsepower (485 kW) and 650 lb.-ft. of torque (881 Nm), it is the most powerful production engine ever offered in a General Motors vehicle. The new LT4 engine builds on the design strengths of the previous LS9 supercharged engine used in the sixth-generation Corvette ZR1 and leverages the technologies introduced on the seventh-generation Corvette Stingray, including direct injection, cylinder deactivation and continuously variable valve timing, to take Corvette performance to an all-new plateau.
In fact, the LT4 produces 40 percent more peak torque (180 lb-ft / 244 Nm) than the previous-generation Corvette Z06’s 7.0L LS7 engine – and 7.5 percent more than the supercharged 2013 Corvette ZR1’s 604 lb-ft (819 Nm). At 3,200 rpm, the new LT4 surpasses the LS7 by 208 lb-ft of torque (252 Nm). On the horsepower side of the graph, the LT4’s 650-hp rating is 29 percent greater than the LS7’s 505 horsepower (376 kW), and 12 horses more than the ZR1’s LS9 engine.
Also new for 2015, the Hydra-Matic 8L90 (M5U) eight-speed automatic transmission for rear- and all-wheel-drive vehicles. The 8L90 is a fuel-saving, electronically controlled eight-speed automatic transmission used with GM full-size trucks and SUVs, as well as the Chevrolet Corvette.
Designed and built by GM, the 8L90 transmission speed is expected to contribute up to 5-percent greater efficiency, when compared to the previous six-speed automatic. Smaller steps between gears, compared to the Hydra-Matic 6L90 six-speed automatic, keep the engine within the sweet spot of the rpm band, making the most of its horsepower and torque to optimize performance and efficiency.