Ever since the Chevrolet Volt was first
announced in early 2007, it has garnered a lot of attention due to its
radical design and unorthodox approach to vehicle propulsion. The Volt's main
source of power comes from a lithium-ion battery pack which can provide enough
juice to power the vehicle for 40 miles. When the battery pack's charge dips
below 35%, a 1.0-liter, turbocharged three cylinder engine was commissioned to
charge the batteries back to 100%. Alternatively, the Volt can be recharged
using a household electrical outlet.
According to GM's Executive Director of Hybrid Powertrain Engineering,
Larry Nitz, the Volt will be ditching
the complex turbocharged three-cylinder engine in favor of a more
conventional naturally-aspirated 1.4 liter four cylinder engine. For its given
application in the Volt, Nitz says that the four cylinder engine provides
better fuel economy which is key in a eco-friendly vehicle like the Volt.
Another advantage to going with the four cylinder engine is
in refinement. While four cylinder engines aren't always known for smoothness
or utmost refinement, they are much better in these respects than three
cylinder engines. "The objective is to keep the engine off and when the
engine comes on, you don't want to know it's on," said Nitz. "You
want it really smooth and four cylinder is smoother than a three."
When it comes to packaging, the naturally-aspirated four
cylinder engine doesn't have to accommodate the turbocharging or its requisite
plumbing; thus it's lighter than original three cylinder engine envisioned for
the Volt. The four cylinder engine, however, is still slightly longer than the
three cylinder engine with its attachments, so changes to the vehicle packaging
had to be made.
Nitz went on to say that the Volt's 16 kWh battery will
provide the best range of performance for the vehicle when operating at a 35%
to 85% charge. Once the four cylinder gasoline kicks in at below 35% charge, it
will provide 50 kW to power the vehicle instead of the usual 100 kW provided by
the lithium-ion battery pack.
Even when operating in this reduced capacity, the Volt will
still be able to respond on command when a surge of power is needed. "Zero
to sixty, passing maneuvers, you'll be fine, the ability to actually use more
than about 50kW doesn't exist very frequently," explained Nitz.
The Chevrolet Volt has made the news quite frequently over
the past month. Most recently, GM announced that it would work with utility
companies to provide
the infrastructure necessary to support electric charging facilities for
electric vehicles like the Volt.
Earlier this month, it was reported that GM reduced
the capacity of the fuel tank from 12 gallons to 7.2 gallons -- this cut
the estimated driving range from 600 miles to 360 miles. Finally, GM Vice
Chairman "Maximum" Bob Lutz in mid-June expressed
his confidence that the Volt will arrive in showrooms in 2010.