A quick tour of those technological features would include:
- Displacement on Demand, which uses a compact switchable tappet to deactivate the valves and shut down half of the V12's cylinders. Cylinder de-activation occurs on the right-hand bank only, Kowalk said, since this allows the engine to run as a perfectly balanced inline-6. Deactivation and reactivation has a quick response time and the oil system and solenoid layout allow valve switching capability at up to 6000 rpm. In May, GM said it will implement Displacement on Demand in its trucks and SUVs beginning in 2004.
- A direct-injection gasoline combustion system provides an increase in engine power, Kowalk explained, while improving fuel economy and cold-start hydrocarbon emissions. "The multiple injection set-up also improves emissions and performance through faster catalyst light-off," he said. "The single fluid high-pressure fuel injector is centrally located in the combustion chamber, and sprays the fuel vertically down to the piston."
- Variable cam phasing helps the Northstar XV12 achieve 90 percent of its maximum torque at 1500 rpm, improves combustion stability at idle, improves fuel economy by reducing pumping losses, and can be used to speed up catalyst light-off to significantly improve emissions. "It provides internal exhaust gas recirculation (EGR)," Kowalk added, "which is more reliable and cost-effective than an external EGR set-up."