Delphi’s dynamic skip fire, developed by Silicon Valley startup Tula Technologies, is set to make its debut in the 2019 Chevrolet Silverado and 2019 GMC Sierra, promising big fuel economy improvements for the big trucks.
While normal drivers may never even realize the system is hard at work, Jason Fenske of Engineering Explained is here to help us understand what exactly is going on with the incredibly advanced cylinder deactivation technology.
Foremost, it makes sense that General Motors will use the system first in V-8s fitted to its full-size trucks since dynamic skip fire, or “dynamic fuel management” in GM-speak, works best with larger engines. The system will allow the engine to run on any combination of the eight cylinders present, meaning it’s possible to deactivate even seven of the eight cylinders.
Dynamic skip fire works by closing off the intake and exhaust valves. For each individual cylinder, a locking pin is present that acts as a hinge. In normal operation, as the camshaft rotates, it presses down on a deactivation arm to open up the intake and exhaust valve. Meanwhile, oil pressure keeps the locking pin in place.
The technology then looks at which cylinder must be fired to maintain engine balance and the power needed on demand. If the cylinder isn’t needed, oil pressure presses the pin back and it won’t hold the deactivation arm. Now, as the camshaft rotates, the valve isn’t activated, thus it does not open, and the cylinder doesn’t fire.
Delphi believes the technology should curb carbon emissions by 7 to 15 percent and drivers should see fuel economy improvements by up to 20 percent, depending on the engine displacement. Small inline-4 engines won’t see nearly as much effect since they’re already fairly efficient, however.