The torque's the thing: 625-hp Z06 Corvette debuts in Detroit
January 13, 2014
Torque, torque, torque. One of GM’s greatest gifts to man has always been bountiful offerings of torque. Nowhere in its vehicle line-up has torque been more plentiful than in the Z Corvettes. Now with the new 2015 Z06 unveiled at NAIAS 2014 in Detroit, torque junkies are set to truly get their 635 lb-ft (816 Nm) fix on.
The 2015 Corvette Z06, sporting a new 8-speed gearbox and 625 hp has clearly been designed with the dietary mandate of chase down and eat any foreign exotics that come across the plate. To accomplish this GM has gone and delicately placed into the forward engine bay, one brand spanking new 6.2-liter, supercharged V8. This new engine will deliver 625 hp via the new 8-speed automatic transmission with paddle shifters or a 7-speed manual. Now manual snobs can get their shift on the old fashioned way if desired.
But the one thing Americanized V8s have always been good at is developing gobs and gobs of torque. Spitting out 635 lb-ft (816 Nm) of torque to the rear wheels gives the new Z06 significantly more torque than a Ferrari 458, McLaren 12C and roughly 35 lb-ft more than Chrysler’s latest Viper.
According to GM, the Corvette’s new LT4 engine gets some of its improved power output from a newly designed 1.7L Eaton R1740 TVS supercharger. Unlike turbochargers powered by exhaust gasses, the supercharger is driven directly by the engine. Capable of spinning up to 20,000 rpm, the new blower not only spins 5,000 rpm faster than the ZR1 LS9 supercharger, but is faster to boost, meaning quicker acceleration and less lag. GM is also quick to point out that, even with the new supercharger in place between the cylinder heads, the entire thing only adds roughly an inch to the overall engine height.
With the new engine delivering 37 percent more power and 40 percent more torque than the Stingray’s LT1 engine, GM had to shore up key engine elements to properly deal with the higher twisting forces and pressures. New aluminum cylinder heads and forged aluminum pistons were incorporated to better dissipate heat and handle pressures in the cylinder chambers with 10:1 compression ratios and increased supercharged inputs. A dry-sump oiling system is also in place to keep the engine profile to a minimum.
So with the boring power bits out of the way, what else has GM done to the Z06 to make it hyper-fantastic. Well that new 8-speed autobox, configured using aluminum and magnesium, features four gearsets and five clutches and is 8 lb (4 kg) lighter than Stingray’s 6-speed, while taking up roughly the same space. GM also reports the new autobox will throw out upshifts 8-hundredths of a second faster than the dual-clutched Porsche 911.
But with all that power comes great torsional responsibility, which is why GM has leveraged much architectural greatness from the new Stingray. The new Z06 will use the same aluminum frame as the C7R track racers, but because of the increased frame design the car will now feature a removable, carbon fiber roof panel. With the roof panel in place the Z06 is 60 percent stiffer than its predecessor.
Another fancy old school trick to better handle torsional power is the inclusion of an all carbon-fibere torque tube. This tube of torque is an encased driveline system, connected directly from the transmission to the differential. Like the system used in my 1963 AMC Rambler Ambassador, the system is designed to reduce twisting forces between the front and back of the car and instead distribute them more evenly across the entire length of the car. This 6.5 ft (2 m) long carbon fiber tube is outsourced from Australia then put in place at the Vette’s factory in Bowling Green, Kentucky.
On the outside, the new Corvette Z06 comes off as something to be taken rather seriously. According to GM, in order to accommodate new everything the design team unconventionally started not with the body, but with the tires.
In order for the car to work as a cohesive package and manage new power outputs, GM had to fit out the car with bigger tires. At 1.5 inches (38 mm) fatter on the front with P285/30ZR19s and 2 inches (51 mm) on the back with 335/25ZR20s, the team had to beef out the haunches accordingly. So the car isn’t just made wider to look meaner, it’s part of a functional mandate where fenders now accommodate bigger tires and larger vent treatments provide increased cooling to brakes, the gearbox and engine bay.
Other design elements like a redesigned front fascia and grille, air blades and larger vents all work in partner to increase cooling and downforce.
Lightweight, spin-cast aluminum wheels on the Z06 are wider than the Stingray at 19 x 10 inches up front and 20 x 12 inches out back, with big honking steel discs and massive Brembo brakes on hand for stopping. The new Z06 also keeps the Stingray’s SLA-type suspension. Third-generation Magnetic Selective Ride Control dampers from the Stingray have been re-calibrated to fit with the Z06’s increased performance demands.
Speaking of aerodynamic enhancements, the Z06 will offer buyers three types of aero-kits. The base Z06 comes standard with a front splitter, a carbon fiber hood with bigger venting and the spoiler from Stingray’s Z51 performance pack. Step up to the next level and GM will throw in a carbon fiber splitter with winglets, carbon fiber rocker panels and one very significant rear spoiler. On the extreme track racing side, the Z07 package will get you bigger winglets on the front splitter and a see-through option on the rear wing.
Inside the car where the important driving stuff happens, the Driver Mode system lets drivers tweak out the car’s traction abilities. An Active stability control system lets drivers switch between track and street modes, while various traction control systems vary the amount of power hitting the back wheels. Interior treatment on the Z06 is similar to that of the Stingrays, with the option of adding Sport or GT Seats to the mix.
GM will make buyers wait until 2015 to get their sweaty hands on the new Z06 Corvette. Performance specs and details will become available over the next year prior to production.
Source: General Motors