Pumping losses are one of the primary energy losses in throttled spark ignition engines. In order to reduce fuel consumption, engine manufacturers are incorporating devices that deactivate the valve-train in some cylinders. In the operating strategies currently implemented in the market, fixed sets of cylinders are deactivated, allowing 2 or 3 operating modes. In contrast, Tula Technology has developed Dynamic Skip Fire (DSF), in which the decision of whether or not to fire a cylinder is decided on a cycle-by-cycle basis. Testing the DSF technology in an independent certified lab on a 2010 GMC Denali, reduces the fuel consumption by 18% on a cycle-average basis, and simultaneously increases the ability to mitigate noise and vibration at objectionable frequencies.
This paper outlines the results of the experiments that have been conducted on an eight cylinder engine over a wide range of conditions to investigate the fuel consumption gains and emissions impact when incorporating DSF technology. The experiments have been carried out over a wide range of engine speeds, loads, and DSF strategies and significant improvements have been observed.