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Written by Dan Carney
Cadillac continues its battle to achieve premium marketesteem equivalent to that of segment leaders BMW and Mercedes-Benz by pushing for top quality and performance in each new model. The high-performance CTS-V is meant to put a stake in theground, demonstrating Cadillac"s seriousness and, to do that, the car isupgraded from the standard CTS in nearly every respect. Visually, the changes start with the bodywork, whichincludes a lightweight carbon-fiber hood and revised front and rear fascias,fenders, rear spoiler, and rocker moldings. An optional carbon-fiber aeropackage adds a front splitter, enlarged wing, diffuser, and carbon-fiber airextractor on the hood. Enlarged intake openings and less obstructive grillemesh contribute to a 50% increase in airflow through the front of thecar to its array of six heat exchangers. "Every exterior detail earned its way onto the car for itsaerodynamic function," stated Product Director Hampden Tener. Aerodynamic effectiveness is critical because the CTS-V isthe fastest Cadillac ever; top speed is 200 mph (322 km/h) and it rockets from 0 to 60 mph (97 mph) in 3.7s. Those flared fenders spread to cover the 19 x 9.5 infront and 19 x 10 in rear wheels. These aluminum wheels are 45% stifferthan those used on the previous-generation CTS-V for more precise steeringcontrol. They mount Michelin Pilot Super Sport summer-onlyperformance tires: 265/35ZR19 in front and 295/30ZR19 in the rear.As with the ATS-V, these custom-tuned Michelins feature three distinct rubbercompounds in the tread, with a hard outer shoulder, grippy inner third, and arain-optimized center section. Inside the wheels are Brembo brakes with staggeredsix-piston front calipers and four-piston rears. The rotors are a two-piecedesign, with a lightweight aluminum center section and cast iron frictionsurface. The 390 mm (15.4 in) diameter fronts are 365 mm (14.4 in) rears aretreated with a ferritic nitro carburized process for corrosion resistance.Customers can choose among three available matte-finish colors for the calipers. At the rear, the CTS continues with a five-link independentsuspension arrangement, while the front McPherson strut setup enjoys dual lowerball joints and a direct-acting anti-sway bar for more precise control. Thesezero-compliance ball joints, stiffer springs, and a stiffer anti-roll barcombine to provide a 20% increase in roll stiffness compared to thetraditional elastomeric bushings. Wheel motion is controlled by BWI Group magnetorheological shockabsorbers, the one-time MagnaRide technology, now in its third generation. A 40% faster response time than before lets the CTS-V respond to changes inthe road surface every inch the car travels at 60 mph. A ZF Steering Systems Servotronic IIvariable-ratio electric power steering rack has 14% greater systemstiffness for improved steering feedback and precision. Underpinning all of these moving parts is a chassis that isreinforced for a 25% increase in stiffness compared to regular CTSmodels. Upgrades include a shock tower-to-tower brace, a shock tower-to-plenumbrace, V brace for the engine compartment, strengthened rocker bulkhead,stronger braces between the rear suspension cradle and the chassis rocker area,and braces from the upper tie bar to the rear bumper. Additionally, a bolt on25 mm (1 in) thick aluminum panel connects the front cradle to the chassis moresecurely. With all this reinforcement, bigger brakes, and enlarged heatexchangers, the CTS-V"s 4145-lb (1880-kg) curb weight comes in 100 lb (45 kg) lighter thanthat of the previous car. The CTS-V"s powerplant is General Motors" supercharged overhead valve6.2-L aluminum block LT4 V8 producing an SAE-certified 640 hp (477 kW) at 6400rpm and 630 lb ft (854 N m) of torque at 3600 rpm. Cadillac notes that these numberstop those of rivals like the 577-hp (430-kW) Mercedes-Benz E63 AMG or the 560-hp (418-kW) BMW M5.Cadillac predicts the CTS-V will achieve U.S. EPA fuel economy scores of 14 mpg cityand 21 mpg highway. As with the current-generation Chevrolet Corvette Z06, which debutedthe LT4 engine, the CTS-V"s powerplant features a smaller-displacement versionof the Eaton supercharger, whose smaller rotors" reduced inertia spin up morequickly under acceleration. The cylinder heads are Rotocast A35T6 aluminum forits greater strength and tolerance of heat. Power transfers from the LT4 to GM"s Hydra-Matic 8L90planetary automatic transmission through a reduced-diameter torque converter.Now 258 vs. 300 mm (10.2 vs. 11.8 in) on the previous car, this torque converter"s reducedinertia contributes to the transmission"s ability to execute upshifts in just150 ms, putting it in the hunt with dual-clutch transmissions forrapid shift times while providing the smooth low-speed driving characteristicsexpected of automatic transmissions. The transmission"s shiftcharacteristics, along with control of the magnetic ride control shocks, powersteering assist, throttle response, and many other variables, are determined bythe drive mode selector. In Touring mode shifts are optimized for smoothnessand fuel efficiency, Sport mode prioritizes keeping the engine revving,and Track mode delivers an amazingly correct shift schedule for all-out racing.There"s also a snow mode that is probably better not tested on the standardsummer-only Michelins. The rear differential is computer controlled so it can betotally open or provide peak pre-load torque, if needed,to transfer power to the tire with grip. Early CTS-Vs suffered axle hop under acceleration, andCadillac"s solution is to use different diameter axle shafts so that theyoperate with different resonant frequencies. In this case, the driver"s sideaxle is 52 mm (2.0 in) in diameter compared to 28 mm (1.1 in) for the passenger"s side. The car"s fuel tank is also located in that vicinity, and Chief Engineer Dave Leone took the opportunity while pointing out critical bitson a rotisserie-mounted car to mention that prototypes had suffered from fuelstarvation at low fuel levels. His team diagnosed the problem by installing aclear gas tank for testing that let them see what was happening inside. Now,owners can hammer the CTS-V around a track at high levels of lateralacceleration (we saw 1.25 g in corners at Road America) with the fuel as low asan eighth of a tank without suffering any fuel-pickup problems, Leone said. Inside, the CTS-V is fitted with extra leather and uniqueoptional $2600 16-way adjustable Recaro front bucket seats. The available Webasto panoramic sunroof, whose large opening easilylights front and back rows, lend the cabin an airy atmosphere. As the first 2016 Cadillac to reach showrooms, it also debuts the second generation of the company"s signature CUE touch-screen infotainment and HVAC control interface. Addressing complaints about the slow, balky performance ofthe first-generation system, Cadillac has upgraded CUE computing hardwareto the Freescale Semiconductor iMX6 processor that, at 4000 millioninstructions per second, is three-times faster than the original chip. Response time is down to 100 ms, which is within shouting distance of an Apple iPhone"s 80-ms response time, so users will find it satisfactory, reported Leone. Critically, destination routing in the GPS navigation system is much fasterthan before, eliminating a key headache. Further, programmers improved thenavigation system interface with the simple inclusion of a "cancel" button onthe map while the system provides guidance. Previously, drivers had to navigatethrough three layers of menus to perform this common task. The center stack display also can now mirror iPhone apps,giving drivers somewhat less distracting access to a few key apps that areenabled for use in the car. Google"s Android Auto is also in the works, accordingto Leone. The CTS-V also features the built-in video camera andCosworth data-acquisition system seen previously on the Corvette Z06 andCadillac ATS-V, letting drivers shoot video of track laps while recording datafrom those laps that is overlayed on the video for easy viewing. With theCosworth Toolbox application on a computer, CTS-V drivers can drill down intotheir data and compare laps or even against another driver"s data to learnspeed secrets for faster laps. Or they can use the data to prove to their friends that theCTS-V is indeed faster than its German competitors.
Date: 11-Sep-2015 10:36 EDT
More of this article on the SAE International website
ID: 1380
Cadillac continues its battle to achieve premium marketesteem equivalent to that of segment leaders BMW and Mercedes-Benz by pushing for top quality and performance in each new model. The high-performance CTS-V is meant to put a stake in theground, demonstrating Cadillac"s seriousness and, to do that, the car isupgraded from the standard CTS in nearly every respect. Visually, the changes start with the bodywork, whichincludes a lightweight carbon-fiber hood and revised front and rear fascias,fenders, rear spoiler, and rocker moldings. An optional carbon-fiber aeropackage adds a front splitter, enlarged wing, diffuser, and carbon-fiber airextractor on the hood. Enlarged intake openings and less obstructive grillemesh contribute to a 50% increase in airflow through the front of thecar to its array of six heat exchangers. "Every exterior detail earned its way onto the car for itsaerodynamic function," stated Product Director Hampden Tener. Aerodynamic effectiveness is critical because the CTS-V isthe fastest Cadillac ever; top speed is 200 mph (322 km/h) and it rockets from 0 to 60 mph (97 mph) in 3.7s. Those flared fenders spread to cover the 19 x 9.5 infront and 19 x 10 in rear wheels. These aluminum wheels are 45% stifferthan those used on the previous-generation CTS-V for more precise steeringcontrol. They mount Michelin Pilot Super Sport summer-onlyperformance tires: 265/35ZR19 in front and 295/30ZR19 in the rear.As with the ATS-V, these custom-tuned Michelins feature three distinct rubbercompounds in the tread, with a hard outer shoulder, grippy inner third, and arain-optimized center section. Inside the wheels are Brembo brakes with staggeredsix-piston front calipers and four-piston rears. The rotors are a two-piecedesign, with a lightweight aluminum center section and cast iron frictionsurface. The 390 mm (15.4 in) diameter fronts are 365 mm (14.4 in) rears aretreated with a ferritic nitro carburized process for corrosion resistance.Customers can choose among three available matte-finish colors for the calipers. At the rear, the CTS continues with a five-link independentsuspension arrangement, while the front McPherson strut setup enjoys dual lowerball joints and a direct-acting anti-sway bar for more precise control. Thesezero-compliance ball joints, stiffer springs, and a stiffer anti-roll barcombine to provide a 20% increase in roll stiffness compared to thetraditional elastomeric bushings. Wheel motion is controlled by BWI Group magnetorheological shockabsorbers, the one-time MagnaRide technology, now in its third generation. A 40% faster response time than before lets the CTS-V respond to changes inthe road surface every inch the car travels at 60 mph. A ZF Steering Systems Servotronic IIvariable-ratio electric power steering rack has 14% greater systemstiffness for improved steering feedback and precision. Underpinning all of these moving parts is a chassis that isreinforced for a 25% increase in stiffness compared to regular CTSmodels. Upgrades include a shock tower-to-tower brace, a shock tower-to-plenumbrace, V brace for the engine compartment, strengthened rocker bulkhead,stronger braces between the rear suspension cradle and the chassis rocker area,and braces from the upper tie bar to the rear bumper. Additionally, a bolt on25 mm (1 in) thick aluminum panel connects the front cradle to the chassis moresecurely. With all this reinforcement, bigger brakes, and enlarged heatexchangers, the CTS-V"s 4145-lb (1880-kg) curb weight comes in 100 lb (45 kg) lighter thanthat of the previous car. The CTS-V"s powerplant is General Motors" supercharged overhead valve6.2-L aluminum block LT4 V8 producing an SAE-certified 640 hp (477 kW) at 6400rpm and 630 lb ft (854 N m) of torque at 3600 rpm. Cadillac notes that these numberstop those of rivals like the 577-hp (430-kW) Mercedes-Benz E63 AMG or the 560-hp (418-kW) BMW M5.Cadillac predicts the CTS-V will achieve U.S. EPA fuel economy scores of 14 mpg cityand 21 mpg highway. As with the current-generation Chevrolet Corvette Z06, which debutedthe LT4 engine, the CTS-V"s powerplant features a smaller-displacement versionof the Eaton supercharger, whose smaller rotors" reduced inertia spin up morequickly under acceleration. The cylinder heads are Rotocast A35T6 aluminum forits greater strength and tolerance of heat. Power transfers from the LT4 to GM"s Hydra-Matic 8L90planetary automatic transmission through a reduced-diameter torque converter.Now 258 vs. 300 mm (10.2 vs. 11.8 in) on the previous car, this torque converter"s reducedinertia contributes to the transmission"s ability to execute upshifts in just150 ms, putting it in the hunt with dual-clutch transmissions forrapid shift times while providing the smooth low-speed driving characteristicsexpected of automatic transmissions. The transmission"s shiftcharacteristics, along with control of the magnetic ride control shocks, powersteering assist, throttle response, and many other variables, are determined bythe drive mode selector. In Touring mode shifts are optimized for smoothnessand fuel efficiency, Sport mode prioritizes keeping the engine revving,and Track mode delivers an amazingly correct shift schedule for all-out racing.There"s also a snow mode that is probably better not tested on the standardsummer-only Michelins. The rear differential is computer controlled so it can betotally open or provide peak pre-load torque, if needed,to transfer power to the tire with grip. Early CTS-Vs suffered axle hop under acceleration, andCadillac"s solution is to use different diameter axle shafts so that theyoperate with different resonant frequencies. In this case, the driver"s sideaxle is 52 mm (2.0 in) in diameter compared to 28 mm (1.1 in) for the passenger"s side. The car"s fuel tank is also located in that vicinity, and Chief Engineer Dave Leone took the opportunity while pointing out critical bitson a rotisserie-mounted car to mention that prototypes had suffered from fuelstarvation at low fuel levels. His team diagnosed the problem by installing aclear gas tank for testing that let them see what was happening inside. Now,owners can hammer the CTS-V around a track at high levels of lateralacceleration (we saw 1.25 g in corners at Road America) with the fuel as low asan eighth of a tank without suffering any fuel-pickup problems, Leone said. Inside, the CTS-V is fitted with extra leather and uniqueoptional $2600 16-way adjustable Recaro front bucket seats. The available Webasto panoramic sunroof, whose large opening easilylights front and back rows, lend the cabin an airy atmosphere. As the first 2016 Cadillac to reach showrooms, it also debuts the second generation of the company"s signature CUE touch-screen infotainment and HVAC control interface. Addressing complaints about the slow, balky performance ofthe first-generation system, Cadillac has upgraded CUE computing hardwareto the Freescale Semiconductor iMX6 processor that, at 4000 millioninstructions per second, is three-times faster than the original chip. Response time is down to 100 ms, which is within shouting distance of an Apple iPhone"s 80-ms response time, so users will find it satisfactory, reported Leone. Critically, destination routing in the GPS navigation system is much fasterthan before, eliminating a key headache. Further, programmers improved thenavigation system interface with the simple inclusion of a "cancel" button onthe map while the system provides guidance. Previously, drivers had to navigatethrough three layers of menus to perform this common task. The center stack display also can now mirror iPhone apps,giving drivers somewhat less distracting access to a few key apps that areenabled for use in the car. Google"s Android Auto is also in the works, accordingto Leone. The CTS-V also features the built-in video camera andCosworth data-acquisition system seen previously on the Corvette Z06 andCadillac ATS-V, letting drivers shoot video of track laps while recording datafrom those laps that is overlayed on the video for easy viewing. With theCosworth Toolbox application on a computer, CTS-V drivers can drill down intotheir data and compare laps or even against another driver"s data to learnspeed secrets for faster laps. Or they can use the data to prove to their friends that theCTS-V is indeed faster than its German competitors.
Date: 11-Sep-2015 10:36 EDT
More of this article on the SAE International website
ID: 1380
