It is no longer taboo for engineers to say that the lust for power can be achieved with smaller-displacement engines.
“I was born and bred that there was no ‘replacement for displacement,” John Juriga, Director of Powertrain at the Hyundai Kia America Technical Center, said during the final session of the SAE 2012 World Congress in the FEV Powertrain Innovation Forum.
But like many consumers, Juriga appreciates that smaller-displacement engines can provide power and fuel efficiency.
The new workhorse in the Hyundai lineup is not a V6. It is a turbocharged, gasoline direct injection (GDI) 2.0-L I-4 cylinder. In the 2012 Hyundai Sonata sedan, this engine has an estimated 33 mpg highway rating, 274 hp (204 kW) at 6000 rpm and 269 lb·ft (365 N·m) of torque from 1800 to 4500 rpm.
“I never heard at clinics or in discussions with consumers, ‘Where’s the V6 option?,'” Juriga said.
With an umbrella topic of “Is There Really ‘No Replacement for Displacement?’ Getting Connected to the Science of Developing Downsized, High Specific Power Engines,” the panelists’ talk included plenty of details about current and future options for turbocharging and supercharging engines.
Audley Brown, Director of Global Advanced Engine Engineering at General Motors, said the proliferation of turbochargers is here and will gain steam. He cited several forecasts, including:
• Turbocharging penetration is forecast to grow from 26% to 33% globally by 2016
• Fixed geometry turbochargers will experience the greatest growth
• Variable geometry applications will grow in volume but decline from 45% to 38% of global turbocharging by 2016.
GM’s turbocharged engines in the 2012 vehicle lineup include the 2012 Chevrolet Cruze and Sonic—both available with the EcoTec 1.4-L turbocharged four-cylinder engine.
The supercharged applications at GM are headlined by the 2012 Corvette ZR1 and the Camaro ZL1. Both sports cars get power from a 6.2-L supercharged V8 (LS9).
Mazen Hammoud, Powertrain Calibration Manager at Ford Motor Co., said that EcoBoost engines will be available in 90% of the automaker’s nameplates in North America by 2013.
Ford’s EcoBoost gas-turbo direct injection engines can facilitate an up to 20% improvement in fuel economy, provide an up to 15% reduction in CO2 emissions, and do so without compromising performance.
Hammoud pointed out that the 3.5-L V6 EcoBoost engine currently represents 41% of sale transactions for the F-150 full-size pickup truck.
Steve McKinley, Vice President of Honeywell Turbo Technologies for the Americas, said engineers are working on the DualBoost gasoline turbocharger concept.
Unlike most gasoline engine turbochargers that use a radial inflow turbine and a single-sided radial compressor—essentially carryover components from diesel engine turbocharger designs—the in-development DualBoost uses an axial turbine and a double-sided compressor.
“With this concept, we came up with a back-to-back compressor wheel and the axial turbine that provides the driver of a downsized, boosted gasoline engine,” McKinley said in a brief interview with an SAE Magazines reporter after the 2-h panel session concluded.
The dual-sided compressor gives the turbocharger “an equivalent flow and pressure ratio. We pair it with an axial turbine that extracts more of the exhaust gas energy during transient conditions more efficiently, and that allows the turbocharger to respond more rapidly, which translates into faster engine response,” McKinley explained.
Honeywell’s aerospace expertise was vital in developing the axial turbine design.
“It resembles jet engine designs. The capability and the technology to be able to design axial turbines was key to making this (DualBoost) project work,” McKinley said.
From a packaging standpoint, the DualBoost’s overall inertia reduction enabled engineers to use a smaller rotor “from a radial perspective, which essentially is the main challenge in packaging standard turbos. It is slightly longer axially to allow the room for the airflow to the back of the second compressor,” McKinley said.
Honeywell’s DualBoost is being prepped for usage with 1.0- to 3.0-L gasoline engines. “That’s our primary focus at the moment,” said McKinley, noting that a production-ready version is expected in a few years. “This (technology) is still in its very early stages,” said McKinley.
Dean Tomazic, Vice President of Passenger Car and Light-Duty Engines at FEV Inc., said that downsizing is also a “very nice recipe for diesel engines.”
In his summary comments, Tomazic noted that engine downsizing in combination with direct fuel injection and boosting (turbocharging and/or supercharging) technology is a “very promising technology path.”
However, more aggressive downsizing scenarios likely would “require two-stage systems for gas applications and potentially three-stage systems for future diesel engine applications,” said Tomazic.