Jacobs Vehicle Systems’ cylinder deactivation technology (CDA) combined next-generation diesel engines has delivered performance-enhancing benefits, according to recent independent validation tests.

The engines, currently under development, are being designed to meet the upcoming round of new U.S. Environmental Protection Agency’s Phase 2 Greenhouse Gas Emissions standards for heavy-duty diesel engines manufactured from 2021-2027.

Independent engine tests have been conducted on Navistar and Cummins engines by Tula Technology, a California-based company that specializes in combustion control and software technology. These tests have confirmed that the Jacobs’ CDA engine systems can deliver improved fuel economy while keeping diesel exhaust aftertreatment systems operating at optimal temperatures, supporting the reduction of NOx and CO₂ emissions.

“Jacobs’ CDA features a hydraulically-activated mechanism integrated into a collapsing valve bridge system for overhead camshaft engines, or with a collapsing pushrod system for cam-in-block engines,” said Robb Janak, director new technologies for Jacobs. “When this is combined with disabled injection in selected cylinders, any combination of cylinders can be deactivated as needed.”

Jacobs’ CDA can be used to shut down engine cylinders at highway cruising speeds, or very low engine loads to improve fuel economy and still keep exhaust aftertreatment systems hot and operating at optimal temperatures to limit NOx emissions, explained Janak.

In the most recent tests with the Cummins engine, Jacobs’ CDA hardware combined with Tula’s Dynamic Skip Fire (DSF) algorithm improved the control of these thermal management modes to simultaneously maximize exhaust temperatures and CO₂ reductions.

“At 1,000 rpm, diesel DSF shows an increase in exhaust temperature of nearly 100⁰ C while still improving fuel consumption by 25%,” as stated in a paper presented to the International Vienna Motor Symposium, along with similar improvements at other operating conditions.

“The Jacobs’ CDA system has been developed over the past 10 years and was specifically designed for the heavy-duty trucking market,” added Janak. “We believe these systems are ready for the market and we are excited with how technologies such as these will improve drivability, emissions and fuel economy.”