Automotive Design & Production is the one media brand invested in delivering your message in print, online, via email, and in-person to the right automotive industry professionals at the right time.
Issue link: https://adp.epubxp.com/i/383875
45 geometry was revised and bearing stifness increased. The independent rear suspension is again a four-link design, but with a new dual lower arm replacing the single lower arm used previously. Combined with the 1.3-in. longer wheelbase—now at 110.3 in., the same as the VW Passat—it provides t Multiple refnements give workhorse 2.4-liter four more power and torque, greater fuel economy. Sport model's 2.0 turbo also is improved. Both will be joined by a 1.6-liter Eco model that features Hyundai's seven-speed dry clutch DCT. opening/closing is controlled by the DC motor-driven continuous variable valve timing. This brings a 2% increase in fuel economy by allowing for late intake valve closing, improved drivability from the system's faster response time, and lower emissions levels at low coolant temperatures. Engineers also increased the fow rate and velocity of engine coolant near the exhaust port to improve fuel efciency at high rpms. Meanwhile, the 2.0-liter turbo gets motor-driven faps in the intake manifold and asymmetrical port plates to enhance tumble and swirl fow when the fap is closed, and increase fow rate when it's open. Optimizing the fow path of the twin-scroll turbocharger brought a 20% improvement in low-end torque, while switching to an electronic wastegate actuator improves boost control. Both engines are mated to a six-speed automatic, though the Sport model adds steering wheel mounted paddle shifters. The naturally aspirated 2.4-liter engine produces 185 hp at 6,000 rpm and 178 lb-ft of torque at 4,000. For the turbo- charged unit these numbers increase to 245 hp at 6,000 and 260 lb-ft from 1,350-4,000 rpm. However, Hyundai has another powertrain combination in its lineup, a 1.6-liter twin-scroll, turbo- charged, direct injection engine mated to the company's frst dry dual-clutch automatic transmission (DCT). It pro- duces 177 hp at 5,500 rpm, and 195 lb-ft from 1,500-4,500. Estimated fuel economy is 28 city/38 highway/32 combined, and it will be the most fuel-efcient model until the Hybrid arrives in 2015. According to Hyundai, the DCT improves fuel economy by 6%-7% and acceleration from 0-60 mph by 3%-7%. improved vehicle stability and more stable high-speed turn-in without adversely afecting ride quality. Surprisingly, Hyundai opted for two diferent electric power steering (EPS) systems on the 2015 Sonata. "We knew the steering wasn't good enough on the YF Sonata due to the tolerance stack-up in the column-mount design," says O'Brien. This compelled the development team to specify a dual- pinion rack-mount EPS with a stifer rack for improved responsiveness. However, development continued on the column-mount design, and the engineers working on that system increased the rigidity of both the column shaft and rack, and moved from a 16-bit to 32-bit controller. "The gains the team made surprised everyone," says O'Brien, "but we continued the two- track approach, placing the rack-mount unit in the Sport model exclusively due to its slightly better on-center response and feel despite its higher cost." Most Sonatas are powered by a 2.4-liter inline four. Sport models get a 2.0-liter turbo. Both direct-injection engines are from Hyundai's Theta II family, and are benefciaries of many improvements. On the 2.4-liter, for example, inlet valve