GM Touts “Skip Fire” Cylinder Deactivation

General Motor Co. says piston engines could hike their fuel economy 15% with a new continuously variable cylinder deactivation system being developed by a Silicon Valley startup funded in part by GM Ventures.

Conventional cylinder deactivation systems conserve fuel by switching off two or more cylinders under low-load conditions. Until now, such systems have been able to move only between fixed firing patterns.

But Tula Technology Inc.'s Dynamic Skip Fire system makes continuous decisions about how many and which cylinders should fire to maintain smooth operation and deliver only the amount of torque required at the moment.

GM says the software-based DSF technology taps the capabilities of digital signal processing and advanced powertrain controls. Tests to date indicate the system could deliver 15% fuel efficiency boosts in 4-, 6- and 8-cylinder engines compared with standard forms of the same powerplants.

Tula's development work combines the company's software knowhow with GM's expertise in powertrain operations. The company's other investors include Khosla Ventures, Sequoia Capital and Sigma Partners.