GM's Larry Nitz discusses Volt, Vue PHEV, 2nd Gen Two-Mode powertrains
Over the course of production development for the past year, the E-Flex engineers have decided to replace the three cylinder with a slightly larger 1.4L naturally aspirated (NA) four cylinder.
Nitz explains that the 1.4L NA four has better brake-specific fuel consumption than the 1.0L turbo when used in steady state mode, as it will be in the Volt application.
Nitz tells GFF "the objective is to keep the engine off and when the engine comes on, you don't want to know it's on. You want it really smooth and four cylinder is smoother than a three."
"It's designed to be able to go up Baker Hill," a steep hill between Los Angeles and Las Vegas as well as other mountain grades at reasonable speeds "just with the engine," Nitz explains.
GM has not yet announced an official on-sale date, although company sources have repeated that late '09 time frame. In spring 2007, Cobasys/A123 Systems and Johnson Controls - Saft were awarded development contracts to supply battery packs for the program. Nitz explains that a significant amount of lab testing has been completed on the batteries and the charging integration is working and is now being refined.
Nitz tells GFF that a second generation Two-Mode system is currently under development. The current variants are used on the full-size GMT900 trucks and the GMT319 Saturn Vue. "We're looking at some additional applications there and lots of applications under consideration with the new fuel economy initiative," says Nitz. "We're going to see a lot hybrids in a lot of different applications."
The second generation system "will get a lot more applications" and will likely launch in the 2012-13 time-frame. Cost reduction will be the "No. 1" effort for the Gen 2 system