Originally posted by 340duster
it doesnt fully shut them down...what it does is put in just enough fuel to keep them alive so that when you floor it, they come back on instantly...but it runs just like an I-4 from my understanding...
http://www.allpar.com/mopar/new-mopar-hemi.html
The system deactivates the valve lifters. This keeps the valves in four cylinders closed, and there is no combustion. In addition to stopping combustion, energy is not lost by pumping air through these cylinders