Hyundai’s Powertrain Approach

Although Hyundai may be most widely associated with creating cars with striking designs, there is no less a commitment at the company to create powertrains that are superbly suited to cars like the Sonata, Elantra, and Genesis. In fact, John Juriga, director of Powertrain Engineering at Hyundai America Technical Center (HATCI) in Superior Township, MI, a complex west of Detroit and east of Ann Arbor, says, “Our goal is to develop the world’s best powertrains,” then admits, “Those are simple words and a bold statement, but it is the mindset of where we are going as a company. Our team is focusing on innovative technology driven by our customers’ desire for fuel efficiency, value and performance.”

Here’s a look at some of the develop-ments that Juriga and his colleague Nayan Engineer, manager of Engine Design and Test at HATCI, outline:

• Gamma 1.6-liter turbo GDI. The first thing to note is that it features a twin-scroll turbo and that the “GDI” signifies that this is a gasoline direct injected engine. The first application of the engine is in the Kia Forte Koup that went into production in late October 2013. (Hyundai and Kia are affiliated as the Hyundai-Kia Automotive Group; Hyundai Motor owns 32.8% of Kia Motors.) The engine produces 201 hp and 195 lb-ft of torque. The Gamma replaces the Theta-II 2.4-liter MPI engine that produces 173 hp and 168 lb-ft of torque. Juriga says that one of the goals in developing the engine was to create something that would be “more fun to drive.” This was achieved, in part, by improving turbo response, from 1.6 seconds to 1.25 seconds. The twin-scroll turbocharger is integrated into the manifold. They’ve upped boost pressure by 10%.

• Nu 2.0-liter GDI. This engine is being used in both the 2014 Hyundai Elantra and the Kia Soul. In the case of the Elantra, the engine is tuned for performance: 173 hp and 154 lb-ft of torque. In the case of the Soul, they’ve tuned it for fuel economy: that version of the engine produces 164 hp and 151 lb-ft of torque. Those are the same numbers for the 2013 Soul, but whereas that engine (with automatic transmission) is rated at 23 mpg city/28 mpg highway, the new Nu provides 23 mpg city and 31 mpg highway. The engine features a dual continuously variable valve (CVVT) system so there is timing of both intake and exhaust valves. There is high-pressure in-cylinder injection which improves combustion efficiency, and thanks to split injec-tion, there is an improvement in exhaust emissions. The crankshaft is offset to reduce friction. There is a variable speed oil pump.

• Lambda 3.8-liter GDI. Unlike the previous two, which are fours, this is a six-cylinder engine. What’s interesting about this engine is that, Juriga says, that compared to the 3.8-liter in the current Hyundai Genesis, “we dropped the power.” That is, the Genesis 3.8 produces 333 hp while the new one is 311 hp. “We didn’t decrease it so much so that it is an issue, but we wanted to pick up the low end torque. Customers spend much of their time at lower RPMs, so we wanted to improve that.” The Genesis 3.8 produces 292 lb-ft while the new one produces 293 lb-ft. (It is worth noting that Hyundai considers the competitive set for this engine to include the 3.5-liter MPI Accord engine, the 3.6-liter Pentastar in the 300S, and the 3.5-liter MPI engine in the Lexus ES 350 to be competitors. The Lambda 3.8 has better horsepower (311) and torque (293) numbers than all of them. Accord, 278/252; 300S, 305/269; ES 350, 268/248.) To achieve the better torque, they’ve deployed a three-step variable intake system that’s tuned for low-mid oriented torque and on the direct injection system they’ve modified the spray pattern from a D-shaped injection to a triangle-shaped injection, which Juriga says improves performance, especially at the low- to mid-range. They’ve also done things to reduce friction, like using a roller timing chain and using a CrN-PVD coating for the top ring on the piston and an MoS2 coating on the piston skirt. There is a variable speed oil pump. A dual CVVT system is used to optimize valve timing.

While these are changes to production engines, Nayan Engineer says that one of the key areas that they are working on with Delphi Powertrain Systems Engineering is the development of diesel-like fuel efficiency from gasoline engines. He refers to what they are working on as an “ultra-efficient internal combustion engine.”

Their approach is not homogeneous charge compression ignition (HCCI), nor is it reactively controlled compression ignition (RCCI). In the former case, there is a difficulty of controlling things like the pressure rise rate. In the case of RCCI, there is the use of gasoline and diesel. “Try selling that to a passenger car driver,” Engineer says.

Their approach is GDCI: Gas direct injection compression ignition. The key is injecting partially premixed fuel very late in the compression stroke and performing the injections multiple times. The fuel injectors are centrally located and they operate at what Engineer calls “GDI-like fuel pressures.” That is, he says they’re working at “sub 500 bar.” The compression ratio is 14.8:1, which is, he says, higher than gasoline but lower than diesel. And there is no spark plug: this is pure auto ignition of the fuel.

The GDCI engine is both supercharged and turbocharged. Engineer explains that  the Eaton supercharger is needed because there isn’t much heat in the exhaust, so it helps create boost where needed. Then the turbo acts as a machine for high-end power. Electric cam phasers are used; they are fast and can be accurately and readily controlled via the engine management system.

Presently, they’re running with con-ventional 87-octane gasoline. The target for fuel economy gains is on the order of +25%.

On the one hand, Engineer says, “If I could go back in time, I’d tell Rudolf Diesel he should have used gasoline.” On the other hand, he acknowledges that GDCI technology is largely made possible on contemporary electronics and other enablers, so back in 1893 things wouldn’t have worked out 
so well.