Eaton Supercharges Audi S4
Audi's Supercharged V6 is a three-time winner of the annual Ward's 10 Best Engines Award. "The Engine delivers tremendous performance...(and a) luxury, powerful driving experience...The supercharger provides luscious low-end torque."
Editor-in-chief, Wards Auto World
Audi introduced the sporty S4 variant of its A4 compact sedan in 2000. The vehicle initially offered a twin-turbo V6 engine, then later switched to a more powerful 4.2-liter V8 and has continued to add content, performance and high-end features over the years.
At the same time, however, competition in the compact, sports luxury market has heated up with new offerings from traditional European players as well as from a host of other international automakers looking to move into the segment. In addition, higher fuel prices and increasingly stringent fuel economy and emissions regulations worldwide are driving automakers to use smaller, more efficient engines.
Audi wanted to up the ante with the next-generation, 2010 S4 and affirm its position in the ultracompetitive premium sports segment. The vehicle needed to hit on all cylinders, including traffic-stopping styling, crisp handling and all-out power.
The car’s engine would be critical to its success in the market. But in addition to delivering the heart-accelerating performance that consumers expect, it also needed to wow them with its fuel-sipping capabilities.
Audi replaced the V8 engine in the previous S4 sedan and Avant wagon with a new direct injection 3.0-liter V6 with an Eaton TVS supercharger, which is available in several other Audi cars and crossover models.
The 2010 S4 also features a new transmission and quattro allwheel drive system, as well as an active sport differential with customized torque distribution to aid high-speed driving. Other goodies include a lowered chassis with aluminum suspension components along with stiffer axle bearings and shocks, high-performance ventilated disc brakes, and upgraded styling and interior appointments.
The Eaton supercharger design boosts power and low-end torque that drivers want while also providing OEMs with the option of using a smaller, more efficient engine with no loss in performance or driveability.
The Roots-type positive displacement supercharger features twin four-lobe rotors that are twisted 160 degrees. The intermeshing, high-speed rotor design pumps air directly into the engine's intake system to generate more power. (By comparison, the original Eaton supercharger featured three lobes twisted 60 degrees.) The fourth lobe and added twist, when combined with redesigned air inlet and outlet ports, creates a smooth, highly efficient flow of air into the engine and has improved noise and vibration characteristics.
The new Audi S4 debuted to rave reviews in late 2009, thanks in large part to the new 3.0-liter supercharged V6 engine. Journalists have lauded the car’s performance, refinement and efficiency. Most notably, Esquire magazine named the S4 its 2010 "Car of the Year." The supercharged V6 powerplant also was honored as a Ward’s "10 Best Engines" winner.
In developing its all-new 3.0L TFSI V-6, Audi opted to use a supercharger with two separate water-cooled intercoolers rather than returning to a twin-turbo design. “Audi engineers did extensive comparative testing and found our new TVS supercharger provided superior throttle response and low-end torque coveted by drivers,” notes Joao Faria, president of Eaton’s Powertrain and Specialty Controls Business. Additionally, when paired with direct injection, the TVS surpasses twin turbochargers in packaging, starting performance and responsiveness.”
Mated to a six-speed manual transmission or an optional seven-speed S-tronic dual-clutch automatic, the engine kicks out 333 horsepower at 5500-6500 rpm—nearly equaling that of the larger V8. Even more impressive: Torque is increased eight percent to 325 lb-ft. at 2900- 5300 rpm. And it takes just 4.9 seconds to sprint from zero to 60 mph—besting the previous S4 by almost half a second.
In addition, fuel efficiency has been significantly improved. Amongst 6-cylinder AWD competitors, the new S4 with the Eaton supercharged engine delivers a class-leading U.S. EPA fuel economy rating of 21 mpg, including 28 mpg on the highway with the S Tronic transmission (27 mpg with the six-speed).
Because they are relatively compact, Eaton superchargers can be placed anywhere near the engine. In the Audi S4, the supercharger is mounted directly on the V6, which sits farther back on the front axle and helps the S4 achieve a weight distribution of 55 percent front and 45 percent rear.
Supercharged engines can also provide up to a 50 percent reduction in emissions during acceleration and deceleration events when compared to a non-supercharged engine creating the same amount of power. They also excel at lowering emissions on cold starts and for start/stop hybrid motors.
For the third year in a row, Audi's TSFI supercharged V6 was named one of Ward's Auto World magazine's "10 Best Engines." After being tested in the S4 with a six-speed manual the last two years, editors evaluated the supercharged powerplant in the larger 2012 A6 with an eight-speed automatic transmission this year. The result was the same:
"The engine delivers tremendous performance...(and a) luxury, powerful driving experience... The supercharger provides luscious low-end torque," said Drew Winter, editor-in-chief, WardsAuto World."
Eaton is the worldwide leader in supercharger solutions, with the technology having been selected by numerous premium global brands. The supercharged 3.0 liter TFSI V6 is a member of Audi’s family of ultramodern V engines.