wastegate actuator, a new intercooler, and ECU
recalibration, raising output to 275 hp.
Theta II-i, the Next Level
The powertrain of the Veloster N centers
on its turbocharged Theta 2.0 T-GDi engine,
which goes by the designation Theta II-i.
This descendant of the Theta II has little in
common with its predecessors, other than the
fact that it has an all-aluminum long-block,
open deck, and 86x86mm bore and stroke
dimensions. Designed for front-wheel-drive
duty, the Veloster N’s Theta II-i boasts a host of
enhancements that contribute to its 275hp peak
output (N Performance Package). Simply put,
this engine is about efficient power production.
Incorporating direct injection into the design
of this engine ensures optimal fuel
atomization. The pistons feature
specially shaped crown profiles that
reflect the atomized fuel back toward
the spark plug for efficient and
complete combustion of the air/fuel
mixture.
The cylinder head design
incorporates the direct injection
system while also improving the
volumetric efficiency. A heat-soak
resistant, polymer intake manifold
features a valve control module
(VCM) linked to valve plates in each
intake runner. The VCM closes
partially at lower engine speeds
to generate a tumble flow effect
for optimal atomization of the air
charge. As engine speed increases,
the VCM opens the valve to permit
unrestricted airflow into the cylinders
under boost.
Next-Generation CVVT
Hyundai engineers improved
the CVVT system for the Theta II-i.
Now, a more responsive electronic
CVVT (E-CVVT) adjusts the intake
camshaft timing, while the traditional
hydraulics continue actuating the
CVVT on the exhaust camshaft. Why
the move to E-CVVT? The electric
motor that adjusts the cam offers
quicker response and a wider range
of timing (compared to the hydraulic
system), which, in turn, permits
calibration settings that help reduce
pumping loss. Since it is electronic,
adjusting the intake camshaft timing
is not dependent on oil pressure. The
exhaust camshaft timing remains
hydraulically controlled since it is
not as critical for the exhaust cam to
adjust as quickly.
Improved Induction
In conjunction with the
improvements made to the block,
cylinder head, and valvetrain, the
Theta II-i benefits from a twin-scroll
turbo. It spools more quickly and
generates boost more efficiently than
the previously employed single-scroll
units. The enlarged turbine housing
does not cause excessive restriction
to the exhaust flow while generating
boost pressure. An electronic
wastegate actuator takes the place
of a traditional vacuum-controlled
wastegate for more precise boost
control.
The electronic CVVT system adjusts the intake camshaft
timing by way of an electric motor instead of relying on oil
pressure, as does the CVVT system on the exhaust side.Cool Under Pressure
While developing and
testing the Veloster N, Hyundai
engineers demanded the car be
capable of running at an open
track day without the need for
modifications, especially when it
comes to combating heat. They
went to great lengths to ensure
adequate heat management
so the Veloster N could take a
beating all day without failure
or overheating. A key factor was
the adoption of a pressurized
coolant reservoir instead of a
simple coolant overflow bottle, creating a closed
coolant circuit. This helps raise the coolant