Hyundai Ioniq HEV
Following the EV by a matter of weeks in early 2017
will be the volume seller and straight-up Prius-fighting Ioniq Hybrid. Power
comes from a 1.6-liter 103-hp and 108-lb-ft Kappa engine augmented by a
43-hp and 125-lb-ft electric motor sandwiched between the engine and the six-speed
dual-clutch transaxle, and fed by a 1.56-kWh lithium-polymer battery that
resides under the rear seat.
That’s more gasoline power and torque, and more
electric torque than the Prius offers, and it’s double the battery capacity of
the Prius with the lithium-ion pack. Hyundai pegs 0-60-mph acceleration at 10.8
seconds. EPA fuel economy ratings for the Ioniq Blue model are 57/59/58 mpg. That’s a new high for non-plug-in models.
Hyundai claims is among the most thermodynamically efficient in
the world, at 40 percent. That efficiency comes from an especially undersquare
design — its stroke is 1.35 times its bore diameter. This reduces the surface area to
cylinder volume ratio, minimizing heat lost to the water jacket. The head and
block are cooled by separate circuits, with a cooler head (190 F) permitting
more aggressive spark advance and a hotter block (221 F) reducing oil viscosity
and friction. Direct injection pressure increases from 2,175 to 2,900 psi, and
the injectors get six laser-drilled holes in a triangle pattern, with the
middle two twice as large as the rest for optimum air-fuel mixing and minimal
wall-wetting.
A highly efficient new exhaust-gas cooler allows
rates of exhaust-gas recirculation as high as 20 percent (about double the
norm). This reduces cylinder temperatures and NOx levels while improving fuel
economy by 3 percent. High compression of 13.0:1 and aggressive Atkinson cycle
valve timing boosts low-load efficiency. Further contributing to the overall
powertrain efficiency is the dual-clutch transmission, which boasts a torque
transfer efficiency of 95.7 percent, and an overall gear ratio spread of 6.93
(typical planetary six-speed autos are much closer to 6.00).
